RA6ZS BGZ Columbia ®ntoer&'tp mtljeCitptflrtriJtork College at f l>p£itwxi& anb burgeon* 3Ubrarp G-ifrf Of PK. H/WEN tM£R OOV-Qax (xAJstAA &~*~*- Practical Preventive Medicine BY MARK F. BOYD, M.D., M.S., C.P.H. Professor of Bacteriology and Preventive Medicine in the Medical Department of the University of Texas; Passed Assistant Surgeon, (Reserve) U. S. Public Health Service; Formerly Epidemiologist of the Iowa State Board of Health and Associate Professor of Preventive Medicine in the College of Medicine of the University of Iowa; Charles Follen Folsom Teaching Fellow in Hygiene, Harvard Medical School 135 ILLUSTRATIONS PHILADELPHIA AND LONDON W. B. SAUNDERS COMPANY 1920 Copyright, 1920. by W. B. Saunders Company PRINTED IN AMERICA PRESS OF W. B. 8AUNDER8 COMPANY PHILADELPHIA TO MY PARENTS Digitized by the Internet Archive in 2010 with funding from Open Knowledge Commons http://www.archive.org/details/practicalpreventOOboyd FOREWORD The following pages represent an endeavor to briefly present the salient features of modern preventive medicine. In a desire to cover the entire field, a great condensation has been effected, which in many instances perhaps results in an in- adequate consideration of important subjects. It is believed this represents the minimum knowledge of the subject which a student of medicine or a practitioner of medicine should be expected to possess. While admittedly brief, the student or reader desiring a broader knowledge will be assisted by the numerous references given. These have been particularly designed to introduce the student to the vast stores of public health literature which exist in the publications of various departments of the United States government. Any individual especially interested in this field should make every effort to acquire those listed- and keep in touch with the new publications issued. The medical profession can play an important role in the field of preventive medicine and public health. At present physicians are neglecting their opportunities.. If this neglect continues the opportunities will lessen and the field will be taken away from physicians by a changing public sentiment. If these pages will bring home to medical students and prac- titioners a realization of their public health responsibilities and stimulate co-operation with public health authorities, the labor of their preparation will have been abundantly rewarded. No originality is claimed for the material here presented. All available sources of information have been freely utilized. Special acknowledgement should be made of the utilization of Rosenau's "Preventive Medicine and Hygiene" to which the specialist or advanced student will naturally turn, and to the report of the Committee on Standard Regulations of the American Public Health Association. Mark F. Boyd. Galveston, Texas, November, 1920 11 CONTENTS CHAPTER I Page Introduction I7 SECTION I DISEASES DUE TO INVADING MICRO-ORGAN- ISMS: EPIDEMIOLOGY CHAPTER II Sources of Infection 24 CHAPTER III Dissemination of Infective Agents 29 CHAPTER IV Contact Transmission 33 CHAPTER V Diseases Transmitted Solely by Contact ^1 CHAPTER VI Diseases Usually Transmitted by Contact 48 CHAPTER VII Diseases Usually Transmitted by Contact (Continued) 54 CHAPTER VIII Diseases Usually Transmitted by Contact {Continued) ....... 59 CHAPTER IX Diseases Frequently Transmitted by Contact 67 CHAPTER X General Measures of Disease Control 74 CHAPTER XI General Measures of Disease Control {Continued) 83 CHAPTER XII Disinfectants and Disinfection 94 CHAPTER XIII Excreta Disposal 104. 13 14 CONTENTS CHAPTER XIV Page Excreta Disposal (Continued) , 114 CHAPTER XV Relationship of Water to Health and Disease 124 CHAPTER XVI Water Purification . 131 CHAPTER XVII Production and Inspection of Milk 149 CHAPTER XVIII Milk as a Route of Infection 167 CHAPTER XIX Other Food Stuffs as Routes of Infection . 175 CHAPTER XX Insects as Vectors of Infective Agents 180 CHAPTER XXI Diseases Transmissible by Insects 188 CHAPTER XXII Lower Animals as Sources of Infection for Man 203 CHAPTER XXIII Other Aspects of Infectious Diseases 220 SECTION II DEFICIENCY DISEASES CHAPTER XXIV Food Requirements: Production and Retail J . . . 223 CHAPTER XXV Diseases Due to Dietary Deficiencies 229 SECTION III OCCUPATIONAL DISEASES CHAPTER XXVI Hazards of Occupation 236 CHAPTER XXVII Occupational Intoxications and Diseases 245 CONTENTS 15 SECTION IV CHAPTER XXVIII Page Diseases Arising From the Puerperal State 255 SECTION V CHAPTER XXIX Diseases Transmitted from Parent to Offspring 260 SECTION VI SPECIAL ASPECTS OF HYGIENE AND SANITATION CHAPTER XXX Hygiene of Infancy 267 CHAPTER XXXI Hygiene of Childhood 275 CHAPTER XXXII Air: Heating and Ventilation 282 CHAPTER XXXIII Certain Aspects of Personal Hygiene 288 CHAPTER XXXIV Domestic Sanitation 295 SECTION VII DEMOGRAPHY CHAPTER XXXV Statistics of Population 301 CHAPTER XXXVI Statistics of Births and Deaths 312 CHAPTER XXXVII Statistics of Sickness 323 SECTION VIII PUBLIC HEALTH CHAPTER XXXVIII Public Health Administration 328 Index 337 PRACTICAL PREVENTIVE MEDICINE CHAPTER I INTRODUCTION Preventive Medicine may be defined as that branch of applied biology which seeks to reduce or eradicate disease by removing or altering the responsible etiological factors. Included within its scope are two subjects which are often confused with it, these are hygiene and sanitation respectively. Hygiene is the proper care of. the body to permit the normal functioning of the various organs and tissues, while sanitation is the proper clean- liness of the environment. Since preventive medicine requires a complete knowledge of the etiology of disease for its application, it is apparent that deficiencies of etiologic knowledge must necessarily limit the scope of successful work. There are however five groups of diseases whose etiology is sufficiently well known to warrant their classification as preventable. The groups are: (I) Diseases produced as the result of the invasion of the body by micro-organisms; (II) Diseases the result of a faulty or deficient diet; (III) Diseases the result of unhygienic or insanitary conditions of employment; (IV) Diseases arising as the result of the puerperal state; and (V) Diseases transmitted from parent to offspring. Despite the fact that the number of diseases included in the above groups is limited, this handicap is very much reduced by the fact that the diseases included in the above groups are for the most part, of considerable importance as causes of morbidity and mortality, so that effective control measures directed against them will accomplish a great deal in reducing the hazards of life. Their importance may be judged from the following mor- tality statistics from the registration area of the United States: 2 17 1 8 PRACTICAL PREVENTIVE MEDICINE TABLE I 1912 1913 Per cent, of total population of U. S. in registration area. .. . 63.2 65.1 Total deaths, all causes 838,251 890,848 Deaths, disease of group 1 287,645 304,580 Deaths, disease of group 2 4,409 15,005 Deaths, disease of group 3 156 171 Deaths, disease of group 4 9,035 10,010 Deaths, disease of group 5 Not a direct cause of death. While the diseases of group 5 are not of importance as causes of mortality, they nevertheless exert a certain definite influence which we will consider later. Directly as well as indirectly these diseases are the cause of immense economic losses. These affect both the individual and the social fabric. The following economic losses may be enumerated: (a) Temporary or permanent disablement of the patient as an immediate result of the disease, resulting to the individual in temporary or permanent loss of earning, and to society in the loss of productive labor; (b) Sequela? or complications which permanently impair the individuals usefulness or hasten death from other causes; (c) Expenses of illness, which if due to preventable illness, must be regarded as an economic loss; (d) The expense incident to the establishment and main- tenance of public hospitals, asylums and charitable agencies to relieve want arising from disabling sickness; (e) Making vast regions of the earth's surface uninhabitable for the civilized races; while (/") Preventable diseases of the domesticated food producing animals may cause such inroads into their numbers that animal foods become scarce and consequently high in price. This is due both to a destruction of the animals as well as to a decreased productiveness of those surviving. With most of the diseases included in the foregoing groups our available knowledge is sufficiently adequate to justify us in classifying them as preventable. Their continued presence with us is chiefly due to the lack of ways and means for placing effective control measures in operation. It may never be practicable to place in operation in civil life the drastic, but nevertheless effective measures which have made the military application of preventive medicine so brilliant, though the ex- perience with military discipline emphasizes the administrative INTRODUCTION 1 9 difficulties which are encountered in the civil application of these measures, where tact rather than force must win the point. Conceiving a population wherein an adequately organized defen- sive and offensive body was available to apply proper measures, we might expect that their continued application would have certain effects. Among these we may prophesy the following: (a) An increase in the period of expectation of life, that is ' the probable duration of the life of the hypothetical average individual. This change will be accompanied by the following phenomena: (i) There will first be a gradual diminution in the total death rate, due to the gradual disappearance of the preventable diseases as causes of mortality; (2) A change in the age distribution of the deaths will next be apparent. The majority of the conditions we are considering are most active as causes of death among the ages below thirty. Their elimination will of course permit a larger proportion of individuals to survive to ages beyond thirty, and as the change takes place the number of deaths above thirty will slowly increase, proportionate to the decrease in the deaths below thirty. (3) The conditions which are operative as causes of death at the age periods beyond thirty, other than those of our particular groups will gradually be found to be responsible for an increasingly greater number of deaths. This state of affairs is not necessarily alarming, but rather is encouraging, as indicating that a larger proportion of individuals are permitted to survive to middle life and older periods. This is, in our opinion, the most rational explanation of the increases which have been observed in the mortality from carcinoma and cardio-renal disease. The completion of this cycle of transformation will probably leave us with a crude death rate from all causes very nearly the same as before the days of even the most feeble preventive work. The important difference will be in the age distribution of the deaths. Instead of the many dying young, the majority will survive to middle life or old age. The individual will have a better chance of living what may be said to be a life of "normal" duration. (b) Unhealthful regions of the earth will be made habitable, consequently human overcrowding will be relieved, and more of the earth's treasures will be available for mankind. (c) The economic productiveness of the individual as well as of the race will be increased. As a consequence individual and national wealth will increase and poverty and want diminish. (d) The supply of animal foods will increase and only be limited b y the available roughage. 20 PRACTICAL PREVENTIVE MEDICINE (e) Lastly we may prophesy an improvement in the general physical condition of the race. The effective operation of the necessary machinery to apply the etiological knowledge we shall briefly sketch may be said to be the problem. It is one of great difficulty and complexity and its complete solution is far distant. Partial means to control the diseases of group one are as we shall presently see, of considerable antiquity, and arose from a recognition that persons infected with communicable diseases were a danger to the public. Thus there developed the field of public health. Originally it arose from a purely selfish attitude on the part of society as a whole to protect itself from certain infected indi- viduals, whose objectionable characteristics arose from no fault of their own. To-day we find a changing attitude, a realiza- tion that if society requires protection by enforcing certain restrictive measures on individuals innocent of crime, justice demands that these persons receive consideration. In addition the field of public health has recently come to have a broader scope, due to the realization that many of our problems, if not all, have a sociological foundation, and that a divorce is not always possible. Relief will only be secured when these associated problems are solved. In a general way our problem of disease prevention has two aspects, namely curative and prophylactic. The curative aspect is primarily the problem of the practic- ing physician and when effectively solved will be manifested by a lowered case-mortality. The physician will be assisted in its solution by the development of methods and the provision of facilities for the making of prompt diagnoses and the develop- ment and application of specific therapeutic measures. This aspect is clearly a problem of the practicing physician in his relation to the individual requiring his services. On the other hand the prophylactic aspect can only give satisfactory results when an entire social unit, such as any community, takes cognizance of its problem and attacks it with all the resources at its collective command. For this pur- pose our social and political units have delegated power and authority to certain officials for the protection of the public health. The problem confronting the officials relates particu- larly to a reduction in the number of cases of preventable diseases in the population under their care. They are not pro- fessionally interested in disease from the individualistic stand- point of the physician. The degree of success achieved by INTRODUCTION 21 these officials will be directly in proportion to the degree in which they educate their public in the principles they are trying to apply. Without the co-operation of the medical profession and the laity health authorities will accomplish very little effective work. In general the field of public health work may be said to have the following scope: (a) Improved personal hygiene of all individuals, including better standards of personal cleanliness, better dietaries, reason- able working hours, recreation and adequate clothing. (b) Improved standards of domestic and public sanitation, including relief from overcrowding, proper illumination, heating and ventilation, water supply, excreta disposal, etc. (c) Improved sanitation of places of employment. id) The immunization of susceptible persons and the con- trol of infected persons. (e) The improvement of the breeding stock of the human race by the elimination of the physically and mentally unfit from reproduction. (/) The provision of facilities for aiding physicians in the diagnosis and care of their patients, i.e., laboratories, hospitals and clinics. Landmarks in the Development of Preventive Medicine. — The only practices of the ancients which we at this day may consider to be preventive measures based upon a firm, rational foundation as we understand the subject, are found described in the Mosaic law. All other practices of the ancients designed to prevent diseases are clearly allied with religion and super- stition, and hence were of little importance and no value. Therefore the Mosaic instructions when interpreted in the light of present day knowledge have an immense importance. These practices however do not seem to have been copied by contemporaneous Gentile races. Aside from the foregoing the earliest public health practice which has survived to the present day is maritime quarantine, which was developed by the mediaeval Italian cities of Venice and Genoa when at the height of their commercial splendor, as a protection against the introduction of plague from oriental ports. At this time the ideas of disease transmission were very vague, but a suspicion of the transmissibility of some seems to have existed. A little later, in 1546, Geronimo Fracastorius published in Venice a work entitled "De contagionibus et con- tagiosis morbis et curatione" in which was first definitely ad- 2 2 PRACTICAL PREVENTIVE MEDICINE vanced the doctrine of contagion. He divided infections into three classes: (i) Those infecting by immediate contact, (2) Those infecting through intermediate agents, such as fomites and (3) Those infecting at a distance or through the air In 1659 Kircher, and in 1675 van Leeuwenhoek first observed and described living organisms too small to be seen by the naked eye. Kircher in 1671 suggested that various infections were the result of the activity of these minute organisms. Kircher's views were received with scepticism by his contemporaries, and later, in 1762, Plenciz of Vienna again advanced the same views. These theories however did not gain headway until the following century, when they were demonstrated scientifically. The first attempt at artificial active immunization among Euro- pean nations must be credited to Lady Mary Wortley Montague, who from 1717 to 1721 introduced into England from Constan- tinople, the process of variolation as a protection against small- pox. This was an event whose importance has been over- shadowed by the employment of an attenuated virus for the same purpose by Jenner. His discovery was first published in 1798. In 1843, Oliver Wendell Holmes, an American physician and author of note, first called attention to the contagiousness of puerperal fever. The activity of water as a route for the trans- fer for infective agents was first recognized in 1854 by Dr. Snow in connection with the famous Broad Street well cholera outbreak. Three years later, Dr. Taylor recognized the simi- lar activity of milk in an outbreak of typhoid at Penrith. The first scientific demonstration of the transmissible character of an infectious disease was performed by Villemin with tuber- culosis in 1865, while the first demonstration of the etiological relation of micro-parasites to disease was accomplished by Pasteur in the case of anthrax in 1876, thus substantiating the earlier beliefs of Kircher and Plenciz. Patrick Manson rec- ognized the first known insect transmitted disease, when he found that mosquitoes transmit Filaria bancrofti. From the time of Jenner no progress in artificial immunization was made until Pasteur demonstrated the protective power of his anthrax vaccine on sheep in 1881, and in 1885 extended the same principle to the treatment of rabies. In 1893, Smith and Kilbourne, two Americans, discovered the cause and means of transmission of the first known insect transmitted protozoal disease, namely Texas fever of cattle. The importance of carriers in the perpetuation of typhoid INTRODUCTION 23 fever was first recognized by Robert Koch, who called attention to them in 1902. Carriers of the diphtheria bacillus had been observed before this, but their importance was not recognized. The results which can accompany the application of the principles of preventive medicine received their first great popular demonstration by Gorgas, when he eradicated yellow fever and malaria from Havana and the Canal Zone. This accomplishment may be considered to mark the beginning of active public interest in the possibilities of preventive medicine, a situation which may be said to characterize the present day. REFERENCES Sedgwick: Principles of Sanitary Science and the Public Health. Chapters II, III, IV. Leviticus — Chapter XIII: 14 Deuteronomy — Chapter XXIII : 1 3 Eager: The Early History of Quarantine. Yellow Fever Institute Bull. No. 12, U.S.P.H. and M.H. Service. Mortality Statistics. Published annually by the Bureau of Census since 1900. SECTION I DISEASES DUE TO INVADING MICRO- ORGANISMS: EPIDEMIOLOGY CHAPTER II SOURCES OF INFECTION i. As a result of the invasion of a population by a given species of pathogenic micro-organisms certain phenomena are produced, some of which are of present interest, particularly those dealing with the incidence or prevalence of disease. This constitutes the field of epidemiology, which may be defined as the science treating of the sources and routes of infection and their activities, as manifested by the incidence or prevalence of an infectious disease in a given population. 2. Before proceeding further certain fundamental definitions had best be presented: (a) An infectious disease is produced as the result of the invasion of the tissues of an animal or plant by a living organism. Because the invading organism may be in many instances transferred from individual to individual of the host species, these diseases are perhaps more aptly termed communicable. Those communicable diseases which are transmitted exclusively or nearly so, directly from host to host are spoken of as con- tagious, or popularly as "catching." (b) Following the invasion of the host by an organism capable of producing disease, a variable period elapses before the char- acteristic symptoms are manifested and during which the ordinary health is apparently maintained. This period is the incubation period. With some infections, as small pox and measles, its length is very constant, with others such as typhoid, it is subject to considerable variation. Its duration is probably dependent upon the number and virulence of the invading organisms on the one hand, and to the specific degree of the host's resistance on the other. (c) A primary case of a communicable disease is the first case arising within a given area, which is the ascribed source 24 SOURCES OF INFECTION 25 of the infective agents transferred to other individuals who later develop the same infection. A secondary case of a communicable disease arises as a result of infection received from a pre-existing known case, with which it has been associated. Both are relative terms. A vector is any intermediate object which serves to transfer infective agents from one host to another. The use of this term is commonly restricted to those insects which occupy this position. An epidemic is the occurrence within a limited time among a limited population, of an unusual number of cases of communi- cable disease. A pandemic is similar to an epidemic, except the population concerned is much larger, that of an entire continent or the world. Endemic refers to the usual prevalence of a communicable disease among a limited population. Epizootic is a term analagous to epidemic, referring to the diseases of lower animals. 3. Sources of Infection. — As a result of extensive bacterio- logic researches as well as epidemiologic studies of similar magni- tude, performed by scientific observers everywhere it may be stated as axiomatic that: All communicable diseases arise from the invasion of a sus- ceptible host by organisms derived from a pre-existing invaded host. The pre-existing invaded host is known as the source of infection. It has long been observed as a fairly constant characteristic that a greater incidence of these diseases was found among in- dividuals in contact with those sick with the same disease, although many cases certainly occur that do not present such a history. At one time in the early days of bacteriologic science it was believed that patients had received infection from organisms that had developed in, and were received from a patient's environment. In other words, the invaders were saprophytes which incidentally possessed pathogenic powers. Such is apparently the actual case with some of the patho- genic fungi. On the other hand, the pathogenic bacteria are apparently of a highly parasitic nature. Bacteriological researches have failed to demonstrate that they can live a sustained vegetative extracorporeal existence. When found without the body it is under circumstances which indicate they are existing within a definite radius surrounding an infected 26 PRACTICAL PREVENTIVE MEDICINE person, and their origin has been undeniably the excretions and secretions of the infected person, and it has been further found that these micro-organisms, with certain few notable exceptions, are only capable of a rather transitory extracorporeal existence, during which period their vital activities are more or less sus- pended and their vitality tends to decrease. 4. The sources of infection as defined above may be classified as follows: (a) Typical Cases. — These are individuals in whom the dis- ease presents the clinical manifestations typical of the disease. (b) Atypical Cases (Abortive or Missed). — These are indi- viduals in whom the clinical symptoms are indefinite or indistinc- tive, and as a consequence are difficult to diagnose. Furthermore the illness is usually mild. Bacteriologic assistance is fre- quently required for a diagnosis, though sometimes, when occurring as secondary cases where the primary case is known, they may be diagnosed clinically. Their proportion to the typical cases varies with different diseases. (c) Carriers are apparently healthy persons who are harboring the specific organisms of communicable diseases and discharging them from their bodies. They are encountered in well defined types. 1. Incubatory carriers, i.e., individuals who are actually in the incubation period of a given infectious disease and will shortly manifest the characteristic symptoms. 2. Healthy carriers, i.e., individuals who throughout the entire period of their harborage never present clinical mani- festations that may be referable to their parasitism. 3. Convalescent carriers, i.e., individuals who have recovered from an attack of the disease in question, but who continue to harbor the specific infective agents. According to the dura- tion of their infectivity, convalescent carriers are commonly arbitrarily divided into two groups: (a) Temporary carriers, whose infectivity subsides in three months following the development of their convalescence, and (b) Chronic carriers, in whom the infective agents persist for periods longer than three months. It must be remembered that the healthy and convalescent carriers possess an active resistance to the micro-organisms they are harboring, so that while they themselves are protected they endanger their associates. The proportion of carriers to cases at any given time with a given disease is subject to wide fluctuations and is difficult of SOURCES OF INFECTION 27 accurate estimation. The carrier condition, in so far as it re- lates to the actual discharge of micro-organism is intermittent. The particular secretions or excretions are not continuously infective, even though the micro-organisms are continually present in the body. In this respect the carrier condition is closely related to the group of sources known as latent cases. (d) Latent Cases. — With certain infections the active clinical manifestations tend to spontaneously subside, though the micro- organisms themselves persist, apparently in a latent condition, for long and variable periods of time, later to renew their ac- tivity when from some intercurrent cause their host's resistance is reduced. During the period of their latency they are not discharged from the body. Latent infection, for example, is observed in syphilis, tuberculosis and glanders. (e) Lower Animals as Sources of Infection. — The foregoing observations relate particularly to the so-called diseases of man, for which human beings serve solely as sources of dissemination. On the other hand, a certain group of human infections, such as rabies, glanders, anthrax, etc., are not due to agents derived from infected human beings, but from infected animals, though the role for the animal as a source of infection is closely parallel. 5. Examples of disease classification in the foregoing types: (a) Atypical forms are encountered in the following infections : Typhoid fever Poliomyelitis Septic sore throat Typhus Fever Measles Diphtheria Asiatic cholera Small pox Meningococcus meningitis Yellow fever Scarlet fever (b) Incubatory carriers have been observed in the following: Typhoid Fever Whooping cough Paratyphoid Fever Measles Malta Fever Small pox Dysentery (amoebic) Anthrax Diphtheria (c) Healthy carriers of micro-organisms producing the fol- lowing diseases have been observed: Typhoid Fever Pneumonia Paratyphoid Fever Meningococcus meningitis Dysentery (amoebic and Gonorrhoea bacillary) Plague 28 PRACTICAL PREVENTIVE MEDICINE Cholera Poliomyelitis Diphtheria Malaria Scarlet Fever (d) Convalescent carriers of the following: Typhoid Fever Dysentery (bacillary and Paratyphoid Fever amoebic) Diphtheria Cholera Pneumonia Meningococcus meningitis Poliomyelitis African Sleeping Sickness 6. Exit of Micro-organisms from the Body of Infected Persons. Different species of micro-crganisms have adapted them- selves to different pathways of exit from the body of infected persons. In order that the propagation of the species be main- tained, it is of course necessary that colonizing individuals be disseminated. For the most part the adaptation is to the natural avenues of exit used for the physiological discharge of surplus secretions or the excretions of the body. To a consider- able extent the adaptation is specific, i.e., certain of these path- ways are more certain to contain micro-organisms producing a given disease, than others. For example the following dis- charges are the means of exit of the infective agents producing: (a) Feces: Typhoid, dysentery, cholera, etc. (b) Urine: Typhoid, etc. (c) Sputum: Tuberculosis, pneumonia, etc. (d) Saliva: Rabies. (e) Nasopharyngeal -secretions: Diphtheria, cerebro-spinal meningitis, etc. (/") Sweat: Typhoid. (g) Milk: Typhoid, Malta fever, tuberculosis. Qi) Epithelial desquamations: Small pox. {i) Purulent discharges: Scarlet Fever. (j) Blood : Malaria, African sleeping sickness. (k) Lachrymal secretion: Conjunctivitis. (/) Placental circulation: Syphilis, tuberculosis. REFERENCES Chapin: Sources and Modes of Infection. Chapter II. Ledingham and Arkwright: The Carrier Problem in Infectious Disease. Simon: Human Infection Carriers. Rosenau: Preventive Medicine and Hygiene. Chapter VII, pp. 362. CHAPTER III THE DISSEMINATION OF INFECTIVE AGENTS i. Stage of Disease in Relation to Dissemination. — (a) Stage of Invasion and Incipiency. — With some diseases such as tuberculosis, when the micro-organisms are in deep- seated lesions not in contact with passage ways to the exterior, the infected person is of little or no active danger to others as a source of infection. On the other hand, with diseases such as diphtheria, where the micro-organisms are in superficial situations having ready access to the exterior, this period is of great importance. (b) Non-infective Stages of Active Disease. — When syphilitic infection progresses to the tertiary and para-syphilitic stages, these as long as they persist are non-infectious. On the other hand, they partake of the character of latent infections, inas- much as relapses to lesions of the secondary type may occur. 2 . Portals Through Which Infective Agents Enter the Body. — Different infective agents have adapted themselves to varying portals of entrance into the body and for the most part, if introduced by a route other than the one to which adapted, fail to gain a foothold. The principal body orifices again play an important part, particularly the orifices of entrance, rather than those of exit. After having passed the threshold of this portal, the infective agents may proceed by divergent pathways to penetrate the physiological interior of the body. The mouth and the nose are portals of entrance of greatest importance from the standpoint of the number of infective agents which are introduced through them. After passing this threshold, some, as the typhoid bacillus may go onward to the intestinal tract, others as the pneumo- coccus procede to the respiratory passages, while others as the diphtheria bacillus, will remain near the point of their entry in the naso-pharynx. Areas of specialized epithelium, as for example that of the conjunctiva or genitalia, are particularly well suited to some infective agents. 29 3° PRACTICAL PREVENTIVE MEDICINE Others, by various means, usually due to some form of traumatism, (inoculation) directly penetrate the outer epithe- lium of the body to the subcutaneous tissues, and thence gain access to the circulation or to the central nervous system. 3. Dosage. — The mere introduction of a given infective agent into the body will not necessarily mean that the micro- organisms will succeed in gaining a foot-hold. The success of a given transfer will vary directly with the number and virulence of the organisms transferred, and indirectly with the resistance of the individual invaded. These factors also in- fluence the duration of the period of incubation. 4. The Extracorporeal Existence of Infective Agents. — The infective agents are for the most part highly specialized para- sites that require for their existence the conditions of tempera- ture, humidity, moisture, and nutrition that they encounter within the body of their host. When these conditions are not available their vegetative and reproductive activities become sluggish, and if prolonged the vitality of the organism may become impaired. Furthermore the colonizing individuals when expelled from the body of their host are ordinarily imme- diately exposed to the action of the natural germicidal agencies, sunlight and desiccation. (See Table II.) In consequence of these factors they become rapidly attenuated and are soon TABLE II Resistance to Sunlight and Desiccation of certain non-spore forming Bacteria. (Compiled from various authorities) Organism Sunlight direct Material Authority Sp. pallida Diffuse — II>2 nrs - Cultures Zinsser Gonococcus Pneumococcus i hr. Hiss & Zinsser Meningococcus Less than 24 hrs. Hiss & Zinsser B. mallei 24 hrs. Hiss & Zinsser Cholera vibrio B. pestis 4-5 hrs. 6 min. film culture Hiss & Zinsser B. diphtheria; Briscoe B. typhosus 9-26 hrs. fabric Sternberg 2 min. fabric Briscoe B. tuberculosis 2 min. fabric Briscoe 45 nrs. sputum Mitchell & Crouch M. melitensis THE DISSEMINATION OP INFECTIVE AGENTS 31 Organism Desiccation Material Authority Xotes Sp. pallida 1 hr. Films Zinsser Gonococcus 18-24 hrs. Pus on fabrics Hiss & Zinsser 1 Pneumococcus 1-4 mo. no • Hiss & Zinsser; In fine spray spu- light turn, 3*2 hrs., ordi- nary light and temperature-Wood. Meningococ- 3 hrs— 2o°C. Besson cus B. mallei 48 hrs.-room temp. Pus, thin layer Besson Cholera vibrio 1 min. Film Strong Dry atmosphere, 6 min., spray wet at- mosphere 30 min. in spray. Strong. B. pestis 5 min. Film Strong Floors — 24-48 hrs. Adv. Comm. India. B. diphtherise 5 days . Film Briscoe Desiccated in mem- brane — 4 mos. still virulent Park & Williams. B. typhosus 5 days Film Briscoe B. tuberculosis 8 days Film Briscoe 2 mos. Sputum Hiss & Zinsser M. melitensis 13-28 days Dust Med. Fever Com. 7-37 days Fabric & Urine Med. Fever Com. Note: Results refer to action of the full physical force concerned. destroyed. It is exceedingly rare for them to gain introduction into any medium favorable for multiplication, such as milk. The fortunate individuals who do succeed in reaching a new host are but a small fraction of those which left the source. These circumstances are our salvation. It must of course be remembered that the spore-forming bacteria such as the anthrax and tetanus bacilli, are exceptions to the rule in so far as survival is concerned, but on the other hand, their numbers probably do not increase during this period. Exception must also be made to certain animal infective agents. These which have a definitive host of course multiply in that species. A few of the multicellular parasites require an extracorporeal period to complete certain stages of their life cycle and are particularly adapted to this. Their degree of 32 PRACTICAL PREVENTIVE MEDICINE specialization as parasites is rot as extreme as it is with the parasitic bacteria. Therefore as a general rule, the closer the relationship in time and space with the source oj infection, the greater is the chance or the successful transfer of unattenuated infective agents. 5. Routes of Transference. — The successful transfer of in- fective agents from host to host is a lottery in which all the chances are against the individual micro-organisms. The perpetuation of the species is secured by the discharge of tre- mendously enormous numbers of individuals from the infected source. Their transfer is effected by means which serve unconsciously to carry human secretions from one person to another. These means may be classified into the following groups in order of their importance. They are: (a) Contact (b) Foods, including Water and Ice. Milk and Dairy Products. Meat and Shell fish. Other Foods. (c) Insects Mechanical transmission. Biological transmission. (d) Soil. {e) Fomites. By the later term we understand objects upon which infective agents may retain their vitality for prolonged periods of time. As a matter of fact, this means of transmission is closely related to certain forms of contact and is only of importance with the spore-forming infective agents. CHAPTER IV CONTACT TRANSMISSION i. By contact transmission we mean the transfer of infective secretions or excretions from one person to another with the lapse of but a short space of time during which interval the in- fective agents are subject to little or no attenuation. From the great variety of infective agents transmitted by this means, as well as the constancy with which opportunities for this transference are encountered, it is the most important of the routes of infection. 2. Means of Contact Transference. — Briefly we may say that contact transmission is accomplished through the con- tinous universal commerce in the body secretions and excre- tions. This commerce is accomplished by the following agencies. (a) Mouth Spray or Droplet Infection. — Every person in talking, coughing, or sneezing, emits from the mouth with more or less explosive force a fine spray of saliva, which will of course contain suspended in it, micro-organisms from the mouth, nasopharynx, or respiratory passages. These particles remain suspended in the air for some time by reason of their buoyancy, but tend to settle out. Air currents may distribute them for short distances. They will of course ultimately evaporate and with evaporation, desiccation of the micro-organisms will occur. The survival of the droplets will of course be longer in a cold humid atmosphere than in a warm dry atmosphere. In a more or less stagnant atmosphere, a quiescent individual may cover a radius of about six feet with these droplets. These are prob- ably of greatest importance when expelled directly onto the body surface of another individual, although the buoyant particles are undoubtedly responsible for the old belief in air- borne infection. (b) Hands and Fingers contaminated with Secretions are undoubtedly the most important agencies in contact infection. Their importance is both from the standpoint of distribution and collection. Fingers are naturally exploratory in their habits, reaching all portions of the body surface and the body 3 33 34 PRACTICAL PREVENTIVE MEDICINE orifices of their owner, thus becoming contaminated with the secretions and excretions, and transferring these to objects later handled. In turn from such objects, the infective secretions of other persons similarly distributed, are collected and introduced into or onto the body of their owner. The ringers of a non- infected person may also transfer infective agents to a third person. It is for this reason that the habits of avoiding the unnecessary introduction of the fingers into the mouth and nose, as well as the habit of washing the hands before eating, are of paramount hygienic importance. (c) A certain communism in small objects was formerly very popular, but fortunately today is looked upon with little esteem. This was the practice of furnishing common articles in public places for intimate personal service, such as drinking cups, towels, combs, pencils and numerous other objects. The intimate use to which these are put renders their contamination by excretions and secretions practically unavoidable, which will be effectively transferred to the next person using them. Des- pite the reduction in recent years of objects, such as drinking cups, which are directly contaminated with secretions, it is prac- tically impossible to always avoid objects which are continually contaminated with human secretions. (d) Lastly, direct approximation of the body surfaces of two different individuals, such as that which occurs during a hand clasp, kissing or sexual intercourse, will effectively transmit infective agents present on one to the other, under circum- stances which of course are altogether favorable to the infective agents. The term direct contact transmission is applied to the second and the last of these agencies, as well as to certain aspects of the first. In these of course, no intermediate objects par- ticipate in the transfer. Distinction between indirect contact transmission and fomites transmission has already been made. 3. Importance of Contact Transmission with Different Infec- tive Agents. — According to the importance of contact in the transmission of different infective agents, we can distinguish several groups of diseases. (a) Diseases Transmitted Solely by Direct Contact. — This group includes the venereal diseases, syphilis and gonorrhoea, which from a practical standpoint are propagated nearly ex- clusively by sexual intercourse. Under these circumstances fresh highly infective secretions are transferred. CONTACT TRANSMISSION 35 (&) Diseases Usually Transmitted by Contact. — This group includes the common so-called " contagious " diseases, for example, small pox, chicken pox, mumps, whooping cough, measles, diphtheria, scarlet fever, common colds, influenza, tuberculosis, meningitis, pneumonia, poliomyelitis, etc. It is known that several of these may be transmitted by other routes of infection, but with all contact transmission is the principle means by which the infective agents are distributed. (c) Diseases Frequently Transmitted by Contact. — With these contact transmission is quite common and is of far greater importance in the propagation of their infective agents than is generally recognized. The spectacular, explosive outbreaks due to the occasional activity of other routes of infection have overshadowed the quiet unpretentious activity of contact in the continued propagation of their infective agents. To this group belong typhoid fever, Asiatic cholera and dysentery (Fig. 3). 4. It is to be noted in the foregoing classification that the varying importance of contact transmission is clearly associated with the route of exit from the body to which different species of infective agents are adapted. As we shall endeavor to show, this naturally influences the distribution of the infective agents. In the first of the foregoing groups, namely the venereal diseases, the active lesions are ordinarily present on concealed portions of the body, on areas covered by the clothing which tend to prevent the very general distribution of infective secre- tions. Transfer of the infective secretions comes as the result of an act, usually voluntary, which places two individuals in such relationship that transfer of the infective secretions is rendered not only possible but probable. In the second of the above groups it will be later learned that the most unusual avenue of exit selected by these micro- organisms, at least the predominating avenue, is that offered by the secretions and excretions leaving by the mouth and nose. The physiological structure of this region is such that these secretions do not accumulate until of considerable volume, but rather the accumulations are small and are expelled at frequent intervals. Furthermore these orifices are not covered by arti- ficial devices, so there is no impediment to the frequent expul- sion of these secretions, neither do any motives of modesty or artificial impediments prevent the introduction of the fingers into either the mouth or the nose. As a consequence these secretions are distributed thinly over a radius corresponding to the daily movements of their producer. 36 PRACTICAL PREVENTIVE MEDICINE In the third group the infective agents chiefly leave the body in either the feces or the urine, or both. These excretions are not expelled continuously but accumulate until the capacity of either the rectum or bladder is reached; thereupon they are expelled. Furthermore, from considerations of modesty these orifices are protected by the clothing, which reduces the fre- quency of finger contamination with these excretions, as well as the frequency with which these discharges are voided. As a consequence these excretions are distributed thickly but irregu- larly over a relatively small radius. 5. Importance of the Different Types of Sources of Infection in Contact Transmission. — The known cases are usually of minor importance in the propagation of these diseases for several reasons. As a result of the invasion they feel ill, consult a physician who usually recognizes the infective character of their illness and directs that a more or less effective regimen of isolation be observed. Even in the absence of a physician, the severity of their illness will tend to restrict their movements or the radius of their activities, and hence temporarily reduce the number of their associates. Both of these factors materially reduce the importance of these patients in the further propaga- tion of their infection, unless perchance they become convales- cent carriers. On the other h'and the unrecognized infected persons are commonly those who experience little or no inconvenience as a result of the infection. As a consequence the radius of their activities is reduced but little, they rarely consult a physician, their infectivity is seldom recognized and hence no precau- tionary measures are employed. Their infective secretions are as a consequence scattered over a wide radius. Thus they are of major importance in the propagation of infective agents. It is therefore apparent the measures of isolation directed against the sources of infection will be successful in inverse proportion to the number of unrecognized infected persons at large in a community. 6. Features Characteristic of Contact Transmission. — {a) The greater the intimacy of association between human beings, the better and more frequent will be the opportunities for the transfer of infective agents by contact. The incidence of con- tact disease is commonly in direct proportion to the density of population in a given area. (b) The intimate association of people at home, at school or in different institutions favors the spread of infection by con- CONTACT TRANSMISSION 37 tact. This aspect is closely associated with housing problems, with over-crowding and inadequate lighting and ventilation, both of which tend to prolong the vitality of pathogenic micro-organ- isms outside the body. Fig. i illustrates housing conditions intensified by overcrowding, that favor the dissemination of infective agents by contact. Fig. 2 illustrates the definite rela- tion of overcrowding to disease incidence, as influenced through contact transmission in the case of measles. Under these cir- FiG. 1. — Mexican corral, city of San Antonio. Front view. The death rate from tuberculosis among residents of buildings of this character is 609 per 100,000, over four times that of the registration area. Lack of facilities for the promotion of personal hygiene, as well as gross overcrowding, in dwelling of this character, favor contact transmission. (From Public Health Reports, April 23, 1915, U. S. P. H. S.) cumstances it will frequently be possible to observe a primary and secondary relationship between the cases that arise, the primary case of course serving as the local source of infection. (c) It is to be noted that most of the so-called "children's diseases are included in the group, "commonly transmitted by contact." In other words, these diseases are most commonly observed during the period of childhood. Several explanations for this fact may be advanced. First, it may be due to the well nigh universal susceptibility of children as compared with the 38 PRACTICAL PREVENTIVE MEDICINE hi J < Id z CD Og Oz Do IS Li_ o OS j z o O J U cr ezzi i o IS 1 E5 i& ■K3 [3 »8 S 2 o < o o in ii- X n' < 2 V m T G h i s jn i 10 q: < hi i 2 > T i 10 > i EC < III i > T i ■ g j i S < UJ > Q J ir 10 I »p ^ < m mm. > Q w rr < > f 3 ir ui n — s z 1 1. 8. j» 1 CONTACT TRANSMISSION 39 active acquired immunity possessed by most adults. Or, since it is well recognized that the promiscuous habits of carefree childhood permit greater opportunities in the unrestricted trans- fer of secretions, it is not improbable that the greater opportuni- ties for contact transfer during this period are of considerable importance in this age incidence. (d) Contact outbreaks or epidemics are never explosive in character, they are always relatively slow spreading, with a gradual rise and decline. This is due to the multitudinous channels through which the infective agents are disseminated, few individuals being simultaneously infected from one source as contrasted with the explosive character of outbreaks follow- fingers Excreta j FROM Patients OR Germ Carriers • 1 y " , - Foods (milk) Vegetables Oysters 0*c. w. w MOUTHS OF Persons flies , -""-£"~" water u^ Fig. 3. — Illustrating the participation of several routes of dissemination in the propagation of the typhoid bacillus. (From U. S. P. H. S.) ing the distribution of infected water or food, where a single contaminated vehicle has simultaneously infected a considerable number of persons. (e) Seasonally, contact diseases tend to reach a maximum prevalence during the colder period of the year. At this period the inclement weather forces the human race within doors, where the degree of personal association is more intimate than that during the warmer period when a greater portion of the time can be spent out of doors. This seasonal distribution is also closely associated with the operation of the public schools. It is also to be noted that continued periods of inclement weather, particularly that characterized by excessive cloudiness 40 PRACTICAL PREVENTIVE MEDICINE is often associated with an increase in the amount of contact transmission, probably by forcing people within doors, as well as by permitting the longer survival of infective agents outside the body, due to the diminished sunlight. REFERENCES Palmer: Opportunities for Contact Infection. American Journal of Public Health; IX-4, April 1919, p. 267 Chapin: Sources and Modes of Infection — Chapters III, IV, V, VI. CHAPTER V DISEASES TRANSMITTED SOLELY BY CONTACT i. From the standpoint of practical importance, we have to consider here but two infections, the so-called venereal diseases, syphilis and gonorrhea. Perhaps in no other infections do we have as forcibly brought to our attention the fact that the questions and problems of preventive medicine are largely of a sociologic nature, since with these diseases dissemination is intimately associated with the problem of promiscuous sexual intercourse and prostitu- tion. One problem cannot be solved effectively without solving the other simultaneously. Their essential aspects from the standpoint of control and prevention may be presented briefly as follows: SYPHILIS (a) Infective Agent. — Treponema pallidum. (b) Source of Infection. — Individuals in the primary and secondary stages of syphilis. (c) Route of Transmission. — By direct personal contact, usually venereal, with infected persons, and indirectly by con- tact with discharges from the lesions, or objects freshly con- taminated therewith. Intra-uterine infection of the fetus also occurs, but is of relatively minor importance. (d) Exit of Infective Agents from Body. — In purulent or serous discharges from lesions on the skin and mucous membranes. (e) Incubation Period. — Usually about three weeks. (/) Period of Communicability . — As long as the lesions are open upon the skin or mucous membranes and until the body is free from the infecting organisms as shown by microscopic examinations of material from lesions. (g) Entrance of Infective Agent into the Body. — Through minute abrasions in the skin or mucous membranes. (h) Methods of Control. — The Injected Individual. — i. Di- agnosis: By clinical symptoms confirmed by the microscopic examination of the discharges (dark field) and by serum re- actions (Wassermann) . 41 42 PRACTICAL PREVENTIVE MEDICINE 2. Isolation: Exclusion from sexual contact and from the preparation or serving of food during the early and active period of the disease, otherwise none unless the patient is unwilling or incapable of observing these precautions. 3. Artificial Immunization : None. 4. Quarantine: None. 5. Concurrent disinfection: Of all infectious discharges and of articles soiled therewith. 6. Terminal Disinfection: None. General Measures.- — 1. Education of the laity in matters of sexual hygiene, particularly to the fact that continence in both sexes and at all ages is compatible with health and physical development. 2. Provisions for the accurate and early diagnosis and treat- ment of venereal patients, in hospitals and dispensaries, with consideration for privacy of the records, and further provision for following patients until they are cured. 3. Repression of prostitution by the use of police power, and control of the use of living premises. 4. Restriction of the sale of alcoholic beverages. 5 . Restriction of quack advertisements of services or medicines for the treatment of sex diseases. 6. Abandonment of the use of common towels, cups, toilet articles and eating utensils. 7. Exclusion of persons in the communicable stages of the disease from participation in the preparation and serving of food consumed by others. 8. Personal prophylaxis should be advised to those who ex- pose themselves to the opportunity for infection. GONORRHEA (a) Infective Agent. — Micrococcus gonorrhea. (b) Source of Infective Agent. — Acute or chronic cases or carriers. (c) Exit of Infective Agent. — In purulent or serous discharges from inflamed mucous membranes and glands of infected per- sons, viz., the urethral, vaginal and cervical mucosa; conjunc- tival mucous membranes, Bartholin's or Skene's glands in the female, and Cowper's and the prostate glands in the male. (d) Routes of Transmission. — By direct personal contact, usually venereal, with infected persons and indirectly by con- tact with articles freshly soiled with the discharges of such persons. DISEASES TRANSMITTED SOLELY BY CONTACT 43 (e) Incubation Period. — One to eight days, usually three to five. (f) Period of Communicability. — As long as the gonococcus persists in any of the discharges, whether the infection be an old or recent one. (g) Entrance of the Infective Agent into the Body. — Through areas of specialized epithelium in the genitalia or conjunctiva. (A) Methods of Control. — The Infected Individual.- — i. Diag- nosis: Clinical symptoms confirmed by bacteriological examination. 2. Isolation: When the lesions are in the geni to-urinary tract exclusion from sexual contact should be enforced, and when conjunctival, exclusion from school or contact with children as long as the discharges contain the gonococcus. 3. Artificial Immunization: Active immunization with stock or autogenous bacterins is extensively employed therapeuti- cally, but the results secured are not uniform. For obvious reasons they are not employed as a prophylactic. 4. Quarantine: None. 5. Concurrent disinfection: Of discharges from lesions and articles soiled therewith. 6. Terminal Disinfection: None. General Measures. — i. Same as those enumerated under this heading with syphilis. 2. Use of prophylactic silver solution in the eyes of the new born. (See preventable blindness.) PREVALENCE OF VENEREAL DISEASES Existing morbidity and mortality statistics do not give us an accurate idea of the prevalence of these diseases in the United States, neither can some of the estimates published by certain ardent champions of sex hygiene be considered as reliable. The army experience gives probably as accurate an idea as any. Thus according to Vedder, of the new recruits received prior to the recent war, 7.75 per cent, were undoubtedly syphilitic; and 9 per cent, more, probably had syphilis. In the second million of the army raised by draft for the recent war, the incidence of venereal diseases, at the time when received, was 5.4 per 1000 men. (See Fig. 3 a.) Among the sailors treated by the Marine Hospital Service it is found that 8.15 per cent, of the annual cases are venereal. As a result of studies upon this question, Banks estimates that 3 per cent, of males 44 PRACTICAL PREVENTIVE MEDICINE acquire venereal infection annually. The incidence is un- doubtedly higher in the American negro. Thus McNeil found in Galveston that between 25 and 30 per cent, of all negroes were syphilitic. The higher incidence of these infections in the DISEASES TRANSMITTED SOLELY BY CONTACT 45 Southern states as shown in Fig. 4, is due to the large propor- tion of negroes in the population. STANDARDS FOR THE DISCHARGE OF CARRIERS The Federal Public Health Service observes the following procedures before discharging venereal patients as non- infectious: A. Syphilis The absence of areas on the skin and mucosa from which the infective agent could be discharged. B. Gonorrhea 1. Males: (a) Freedom from discharge. (b) Clear urine without shreds. (c) Pus expressed from the urethra by prostatic massage must be negative for gonococci on four successive examinations at intervals of one week. (d) After dilation of the urethra by the passage of a full sized sound, the resulting inflammatory discbarge must be negative for gonococci. 2. Females: (a) No urethral or vaginal discharge. (b) Two successive negative examinations for gon- ococci of the secretions of the urethra, vagina, and cervix, with an interval of 48 hours between, and repeated on four successive weeks. MEDICAL PROPHYLAXIS OF VENEREAL DISEASES The prompt application of disinfecting substances to the genitalia shortly after intercourse with prostitutes has given excellent results in the army and navy. This method has justly received criticism, inasmuch as it does not tend to en- courage continence. The following has been employed for this purpose: (a) Scrub the entire penis with green soap and water. (b) Wash the penis well with 1:2000 bichloride of mercury, paying especial attention to the frenum. (c) Have the patient pass his urine and give an urethral injection of 2 per cent, protargol, which is retained for 1 to 2 minutes. The following results with this treatment were secured in the U. S. Navy between May 1, 19 10 and Aug. 31, 191 1. 46 PRACTICAL PREVENTIVE 1LEDICINE When applied within 8 hours after exposure, there were 19 infections in 1385 cases, or 1.37 per cent. When applied within 8 to 12 hours after exposure there were 25 infections in 741 cases, or 3.31 per cent. When applied within 12 to 24 hours after exposure there were a6 infections in 920 cases, or 5.00 per cent. PREVENTABLE BLINDNESS This question can perhaps be best considered at this time, in as much as certain aspects are closely associated with the venereal diseases. There are approximately 64,000 registered blind in the United States of whom 10 per cent, owe their blindness to ophthalmia neonatorum, while 59 per cent, of the admissions to special schools for the blind owe their handicap to the same infection. Other causes of blindness are the ophthalmias of later life, syphilis, sympathic inflammations, industrial and other accidents, pro- gressive near sightedness, functional disturbances of vision, amaurosis and optic atrophy caused by poisoning from lead, alcohol, tobacco, etc., and wood alcohol. (a) Ophthalmia neonatorum. — This term includes all in- flammatory conditions of the conjunctiva that occur before the end of the first month of life. Infection usually occurs during the passage of the child through the parturient canal and is derived from the vaginal secretions of the mother, though it may also occur from infection after birth. The gonococcus is the most important single organism in its production, being demonstrated in about 65 per cent, of the cases. This disease is observed in from 6 to 10 of each 1000 births. It may be effectually prevented by the employment of Crede's method of prophylaxis, which should be always used regardless of the venereal history of the parents. It is as follows: Clean the eyes with a pledget of cotton and boric acid solution. Sepa- rate the lids and instill 1 to 2 drops of 1 per cent, silver nitrate solution, which in a few minutes is washed out with saline. In order to encourage this practice many states distribute free outfits of these solutions for the employment of this treatment in all newly born. (b) Trachoma is probably not a specific infection, although this is disputed. It is found among those living under defective sanitary conditions, and is extremely chronic. Infec- tion is transmitted by the conjunctival secretions which are disseminated by the fingers, roller towels and handkerchiefs. DISEASES TRANSMITTED SOLELY BY CONTACT 47 REFERENCES Rosenau: Preventive Medicine and Hygiene, 3rd Ed., pp. 54-74. Vedder: Prevalence of Syphilis in the Army. Bulletin 8, Office of Surgeon General, U. S. Army. Pusey: Syphilis as a Modern Problem. American Medical Association. Clark axd Schereshewsky: Trachoma: its Character and Effects, U.S.P.H and M. H. Service. A Symposium on Venereal Disease Control in the Army, the Navy and the Civilian Community. By Gorgas, Russell, Holcomb, Fosdick, Kerr, and Frost. Social Hygiene: IV— i, Jan., 1918. A Manual for the Treatment of Venereal Diseases. American Medical Association, Chicago. The control of venereal disease. Reprint 447, Public Health Reports. Syphilis, some of its public health aspects. Reprint 354, Public Health Reports. A state plan for the prevention of venereal disease. Reprint 455, Public Health Reports. Instructions to medical officers in charge of state control of venereal disease Misc. Pub. 19. U. S. P. H. S. Trachoma in Kentucky. Reprint 101, Public Health Reports. CHAPTER VI DISEASES USUALLY TRANSMITTED BY CONTACT This group includes the diseases whose infective agents are most commonly propagated by secretions leaving by the mouth and nose, and for number exceed in importance the other groups. Thus we have to consider by reason of this importance, the following: Chicken Pox Diphtheria German Measles Influenza Measles Leprosy Mumps Pneumonia (acute lobar) Poliomyelitis Scarlet Fever Septic Sore Throat Small Pox Tuberculosis (pulmonary) Whooping Cough. Cerebrospinal Meningitis SMALL-POX (a) Infective Agent. — Unknown, but it is a filterable virus. (b) Source of Infection. — Typical or atypical cases in the active or prodromal stages. (c) Exit of Infective A gent. — In the secretion s of the mouth an d nose (possibly the feces and urine) and discharges from the lesions. (d) Routes of Transmission. — By direct or indirect personal contact, and possibly by flies. (e) Incubation Period. — Ordinarily 12 to 14 days, sometimes 21. (/) Period of Communicability. — From the first appearance of symptoms until the disappearence of all scabs and crusts. (g) Entrance of Infective Agent into the Body. — Probably through the nose. (h) Methods of Control. — The Infected Individual. — 1. Diag- nosis: By the clinical manifestations. Differentiation of a- typical cases from chicken-pox may be achieved by the Tieche test. 2. Isolation: Hospital isolation in screened wards is pref- erable, continued until the period of communicability is over. 48' DISEASES USUALLY TRANSMITTED BY CONTACT 49 3. Immunization of contacts: By vaccination. There is no means of employing passive immunization. 4. Quarantine: Segregation of all exposed persons for 21 days from the date of last exposure, or until protected by vaccination. 5. Concurrent disinfection: Of all discharges and articles soiled therewith. 6. Terminal disinfection: Thorough cleaning and disinfec- tion of the premises. General Measures. — 1. General vaccination of all persons in infancy, revaccination on entering school, and of the entire population when the disease is prevalent. Small-pox Vaccination. — (a) The importance of this means of protection, as well as the possibility of serious or untoward results from its application, demand its consideration in some detail. (b) Glycerinated virus, put up for distribution in capillary tubes and which has been stored in a refrigerator, should only be employed. One should be sure the date of expiration has not passed, as it is exceedingly important to use fresh, potent virus. (c) Select for vaccination the left arm at the insertion of the deltoid. Cleanse the arm thoroughly by rubbing with green soap, wash with water, and follow with alcohol. Allow the skin to dry. With a flamed needle make three parallel scratches about 1 to }£ inches long and % inch apart, taking care not to draw blood. Expel the contents of vaccine tube on the two outer scratches and with shaft of the needle rub the virus well into scratches. Allow to dry for 10 to 15 minutes. Upon appearance of the eruption it may be covered with a sterile dry dressing. (d) Course of Eruption in a Primary Take— (a) Period of Incubation. — This is from 3 to 4 days duration. The inocula- tion scratches will have entirely healed in two or three days. (b) Period of Papule. — Along the site of the inoculation scratches one or more small, round, flat, bright red and super- ficial papules make their appearance. These may be confluent. (c) Period of Vesicle. — On the fifth day a small clear vesicle will appear in the center of each of the papules. The area around the vesicles becomes red and swollen and enlarges as the vesicle ^enlarges. The vesicle is multilocular and umbili- cated. It is mature by the eighth day. 4 5 ,?/-<»/? pi/rc I) trjej e-f eretm or 6(//?&r ait /Ac . Others in family using same dairy products ? , . (E) Other f ood : . . Meals where taken : Solely? Principally ? ■ r _ j Occasionally ? Banquets, picnics, excursions or other gatherings attended where food, milk or water consumed? Celery? Source? Lettuce? Source? Radishes? t Source? Oysters, etc? Source? Cold meats? , Salads ? Source? , ; Other foods? Others in family who partook of same food ? ■ Delicatessen foods eaten ? Source ? Nature ? Do servants eat same food as family? , ._.., 90 PRACTICAL PREVENTIVE MEDICLNE (F) Out-of-town' (with-in-town) trips witliin 30 days prior to illness ;■ Where to?.... ;.. ..When? Route taken?. . . » « . . J .Stops? Meals taken? .Water?. Milk ? . What else eaten? -....., Place stopped at?... .."..... ..., Sanitary condition? Places visited ? , Where to? , . When? Route taken?.....,...., .......Stops? Meals taken?..., Water?. Milk?. Place stopped at? .,..,.,,...., ....Sanitary condition? Places visited? . -. . .......................... Known contact at these places?....... Others of family who made same trips? .• Sathing or swimming?....;....; (4).. CONCERNING FURTHER SPREAD Did patient continue at usual work while feeling-Ill (milk and food handlers) ? Disposal of discharges during this' period ? » Antityphoid vaccination of contacts?, .;, No? Date of beginning precautions against spread? , .-, Isolation of patient?: Effective: Non-effective? Disinfection of feces?. , Urine?. , Manner of disposal of excreta at present?. , Screening of patient's bedroom ? Other prophylactic measures ? Kurse: trained or lay? Name , . Date of relaxing precautions? ^. Condition of infectiveness or discharge? Investigator. GENERAL MEASURES OF DISEASE CONTROL 9 1 8. Analysis of Epidemiologic Data. — In undertaking such an analysis it is important to locate the cases both from the stand- point of place and time, as this will yield important information. First however, the imported cases should be excluded from the analysis. A case is regarded as if imported if either (a) brought into the local area while ill, or (b) if out of town at at the probable time infection was received. The principal consideration they should receive will relate to their potentia- lities as a local source of infection. To localize the cases from point of space they should be plotted upon a map of the district according to their place of illness at the time of onset. One should then note if their dis- tribution is localized or generalized, and if it has any definite relation to possible neighborhood activities, or water or milk supplies. From the standpoint of time the case should be plotted upon co-ordinate paper according to their dates of onset. From the curve thus secured one should note whether the course of the epidemic is abrupt or explosive in its rise and fall, or slow and gradual. The former curve indicates that the cases owe their infection to the use of some common route of infec- tion, such as water, milk, etc., in other words that their infec- tion has been simultaneous. The slow rise and fall of the curve indicates contact transmission or fly transmission. The contact transmitted diseases with short incubation periods and great virulence, such as influenza, will produce an epidemic curve much more abrupt than that produced by the other diseases of this group, having longer incubation periods. If the curve is explosive, analysis of the data secured under the heading of probable routes of infection, should be made to ascertain the route of infection common to all cases, at least those of the explosive period. When ascertained this must be further investigated to reveal the source from which the route became contaminated. On the other hand, if the outbreak had a slow rise and fall the contact histories will for the most part link up with one another, excepting for gaps produced by transfers of infective agents from unrecognized infective persons. Epidemics due to different types of routes of infection have certain peculiarities, to which attention will be called when considering these routes in detail. As soon as the infected route of transmission is ascertained proper measures to render it innocuous must be immediately 92 PRACTICAL PREVENTIVE MEDICINE inaugurated. When this is done the epidemic will draw to a close except perhaps for a few scattered contact cases. The probable time of infection is reckoned by subtracting the average incubation period from the date of onset. 9. Emergency and Routine Epidemiology. — Emergency epi- demiology is the application of the principles presented in the foregoing paragraphs and chapters in the face of the emergency produced by an epidemic, and epidemics usually result from a deficient or inadequate public health organization. The work is usually done in the face of the epidemic, actually at a time when the danger is at a maximum or tending spontaneously to decline. The remedial measures employed are usually of a temporary character, aiming principally at a control of routes of infection rather than sources. On the other hand, the routine application of the foregoing methods day after day to each case of communicable disease recognized, will soon show results in a reduction of both morbidity and mortality, and extensive epidemics will be prevented. Small epidemics may occur due to unrecognized importations of infection, but these will not have a chance to spread. This is routine epidemiology, which not only aims at a permanent control of the routes of infection, but of the sources as well. 10. Education of the Public in General Cleanliness. — The education of people in personal hygiene will do much to pre- vent the spread of diseases, as well as secure their co-operation with health officials. The following points in general cleanliness are of special importance in this connection : (a) Washing the body frequently with soap and water. (b) Washing the hands with soap and water after voiding the bowels and bladder, and always before eating. (c) Keeping the hands and unclean articles, or articles that have been used for toilet purposes by others, away from the mouth, nose, eyes, ears and vagina. (d) Avoiding direct exposure to the spray from the noses and mouths of people who cough and sneeze, or laugh and talk loudly or in an explosive manner. (e) Avoiding the use of common or unclean eating, drinking, or toilet articles of any kind, such as towels, hair brushes, drink- ing cups, pipes etc. (/) In epidemic periods public assemblages should be dis- couraged and the wearing of masks should be encouraged. (g) Promiscuous spitting should be prohibited. GENERAL MEASURES OF DISEASE CONTROL 93 REFERENCES Barry: Aseptic Nursing of Infectious Diseases. American Journal of Nursing. 1916, XVI, pp. 8. Crowe: Aseptic Technique Method for Contagious Hospitals. Journal Michi- gan State Society, 1916, XV, p. 5. Curtis: Nursing in Contagious Diseases. The Modern Hospital, 1914, 11, p. 127. Schmidt: Hosipitals for Communicable Diseases (with bibliography). The Modern Hospital, 1918, X, pp. 153. A Model State Law for Morbidity Reports. Reprint 133, Public Health Reports. Morbidity Reports : Their importance to the local health officer and his work. Reprint 153, Public Health Reports. Brooks and Godfrey: The prevention and control of communicable diseases. New York State Department of Health. 1919. CHAPTER XII DISINFECTANTS AND DISINFECTION The importance of disinfection in connection with isolation permits this subject to be considered to best advantage at this time. Disinfection may be denned as the destruction of infective agents where ever they may be; while disinfectants are agents capable of producing disinfection. Disinfection is not neces- sarily the same as sterilization, by which process we mean the certain destruction of all forms of life. i. Disinfectants in Relation to the Body. — In relation to the body disinfectants may be either internal or external. (a) Internal disinfectants are employed chiefly as therapeutic agents, though some endeavor has been made to employ them in the sterilization of carriers. Their employment is the basis of specific therapy as applied to infection. As examples one may site the employment of mercurials and arsensicals in syphilis, of quinine in malaria, of ipecac in amoebic dysentery and ethyl-hydro-cuprein in lobar pneumonia. (6) External disinfection is the practice in which we are at present interested. It is employed upon infective agents with- out the body under the following circumstances: i. As they leave the body in the infective secretions and excretions. 2. After they have been distributed in the environment of the patient. 3. After they have gained access to their definitive (insect) host. 2 . Disinfecting Agencies may be Either Natural or Artificial. — We may perhaps best consider them according to whether their action is physical or chemical. (a) Physical Disinjectants. — The natural agencies of disin- fection are for the most part physical in character and com- monly their importance is sadly ignored. Their efficiency is undoubtedly the principle reason for the salvation of most higher organisms from the ravages of the lower parasites, as witness the extraordinary numbers of these which are dis- 94 DISINFECTANTS AND DISINFECTION 95 charged from the infected host while so few succeed in reaching a new host. Most of these countless parasites are doomed to certain destruction by these natural agencies (see Table II, page 30). The physical agencies include the following: 1. Dessication. 2. Heat, either in the form of dry or moist heat, or complete incineration. Moist heat may be artificially employed either as boiling water, streaming steam, or steam under pressure. 3. Light: particularly sun light, and of the sun's rays the ultra-violet are those of greatest bactericidal action. (b) Chemical Disinjectants. — Most of the artificial methods, particularly these employed in connection with medical asepsis in isolation are of this group. These are either: 1. Liquids, which in turn are either: Solutions, such as bichloride of mercury, phenol, formalin, iodin, chlorin, bleach, etc., or suspensions, such as the cresol compounds. 2. Gases, such as sulphur dioxide or formaldehyde. The employment of gaseous disinfectants is known as fumigation. 3. Manner of Action. — Different agencies exert their lethal action in different ways. Some of the lethal effects are known, but our knowledge of the means of their action" is obviously incomplete. Among these we may consider the following: (a) Abstraction of water, i.e., dessication. This may be lethal to some organisms, or cause others to enter upon a con- dition of suspended activity. (b) Coagulation of the protein of the micro-organisms, either with or without an ionic poisoning of their protoplasm. The first is produced by the action of metallic salts, while such agen- cies as phenol do not produce an ionic poisoning. (c) Destruction by emulsoid action. The lethal effect is due to a molecular bombardment of the micro-organism by the finely suspended particles, associated with a certain amount of poisoning through absorption. (d) Oxidation of the protoplasm, such as that produced by ozone, chlorine, or the permanganates. 4. Standardization of Disinfectants. — Accurate comparisons of the efficiency of disinfectants, parlicularly of their efficiency under conditions of actual employment is very difficult, due to the absence of suitable standards. Laboratory experimenta- tion together with empirical experience has demonstrated the effectiveness and reliability of the disinfectants in the dilutions later named. It is when one is called upon to express an opin- 96 PRACTICAL PREVENTIVE MEDICINE ion as to the use of some proprietary preparation of uncertain strength and composition, that the greatest need of such standards is felt. While some progress has been made, in the comparison of the relative efficiency of these substances, the question of standarization is still far from settled. This is chiefly due to the great number of factors which influence the activity of disinfectants, the different conditions under which they must act in practical employment, and the species of infective agent upon which they may have to act. The most important ad- vance in this direction was the method introduced by Rideal and Walker, of which other recent methods such as the Hy- gienic Laboratory method are modifications. In the deter- mination time of action and temperature of exposure are arbitrarily taken as constants and the strength of the disin- fectant solutions as the variable. Phenol has been chosen as an arbitrary standard. Cultures of B. typhosus in broth have commonly been employed as the test organism. In practice varying dilutions of the standard phenol are compared with varying dilutions of the unknown disinfectant being tested, until dilutions of the two are found which kill after the same period of exposure, usually arbitrarily taken at seven minutes. The results are expressed by dividing the lowest dilution of the unknown by the lowest dilution of phenol which killed in the same space of time. The result is called the carbolic coefficient of the unknown. A low carbolic coefficient, expressed as a number less than unity, usually means the substance possesses slight disinfecting value. On the other hand, the possession of a high coefficient does not necessarily mean a substance is suit- able for practical use. Other factors must be taken into consideration. 5. Properties of an Ideal Disinfectant for External Use. We can specify certain properties which an ideal disinfecting substance should possess, but unfortunately we possess no dis- infectant in which all these properties are simultaneously pres- ent. They are the following, and their importance is self-evident : (a) It should work effectively, i.e., disinfect, with or without the presence of organic matter. (b) It should be reasonably stable from a chemical stand- point. (c) It should be soluble or miscible in water. {d) It should be harmless to man or higher animals while highly toxic to micro-organisms. (e) It should possess great powers of penetration. DISINFECTANTS AND DISINFECTION 97 (/) It should not corrode metal, bleach pigments, or rot fabrics. (g) It should be commonly available at a reasonable price. (h) It should be effective against all infective agents. 6. Conditions Influencing the Efficiency of Disinfectants. — {a) Strength of solution employed: As a general rule the activity of disinfectants is directly proportional to their concentration, while very potent substances may be so highly diluted that they are without effect. (b) The length of time in which they are permitted to act: No disinfectant, with the possible exception of incineration, is in- stantaneous in its action od all the infective agents present in a given medium. An appreciable length of time must elapse for its effect to be achieved. (c) Certain agencies exert what is known as a selective ac- tion. That is they are lethal for some micro-organisms but without action on others. Therefore one must use a certain amount of discretion in the selection of a disinfectant for the destruction of a given parasite. (d) The material to be disinfected may influence the results in several ways. First, organic matter may afford a mechanical protection for the infective agents and thus defeat our purpose, or there may be a chemical combination between the disin- fectant and other substances present, as a result of which the effective quantity of our agent is seriously reduced. Or lastly, the material may contain resistant stages of the micro-organ- isms, such as spores, which are not readily affected by the agen- cies of disinfection selected. While it is theoretically possible to estimate the necessary quantities of disinfectant to apply in any given case, yet in practice it is difficult to estimate the effect of the foregoing factors, since they are extremely variable. Hence in practice disinfectants must be employed in excess quantities. 7. Technic of Concurrent or Concommitant Disinfection. The number of substances suitable for the purpose is not large, if we select those which most nearly possess our ideal properties. The following solutions may be considered standard. (a) For the disinfection of feces and urine the following may be used : 1. Formalin in 10 per cent, solution. Mix equal volume of this solution with the excreta and allow to stand for one hour. This is very effective, but the irritating fumes prevent its use in the sick room. 7 98 PRACTICAL PREVENTIVE MEDICINE 2. Phenol in 5 per cent, solution. Mix equal volume of this solution with the excreta and allow the mixture to stand for one hour. 3. Unslaked Lime. — Add a quantity of unslaked lime of approximately equal volume to the excreta and mix well by means of a small stick. Cover with 1 to 2 quarts of boiling water and allow the mixture to stand for two hours. This is one of the cheapest methods. 4. Chlorinated lime, in 3 per cent, solution. One must be sure that the preparation is fresh, otherwise its strength will be greatly reduced by loss of the chlorine. Mix equal volumes of excreta and the solution and allow to stand for one hour. 5. Liquor cresolis compositus in 2 per cent, solution. This is one of the cheapest and best substances for this purpose. Mix equal volumes of the excreta and disinfectant and allow to stand for one hour. 6. The foregoing will prove satisfactory for the destruction of bacterial infective agents in the feces, but will not destroy protozoan parasites or helminth ova. According to Dr. C. W. Stiles either 3 per cent, sodium hydroxide or four tenths per cent, sodium dichromate may be used to destroy protozoan parasites or helminth ova. Most species are killed relatively soon by this treatment, but the ova of Ascaris or Oxyuris may require from four to six days exposure before they are destroyed. (b) For the disinfection of discharges from the mouth and nose. Undoubtedly the simplest method of handling these secre- tions is to collect them on old rags or paper napkins, or in spu- tum cups, and incinerate these when filled. When using cloths or napkins the patient shuld be instructed to carefully fold in the contaminated area so that contamination of the fingers is reduced. Any of the substances recommended for the dis- infection of feces and urine may also be used. (c) For the disinfection of bed linen and clothing, bed pans and other contaminated objects, immersion for one hour in the foregoing solution of chlorinated lime or liquor cresolis com- positus is satisfactory. Dishes should be received into a dish pan kept for this pur- pose, covered with water and boiled before washing. Food remnants should be incinerated. 8. Employment of Fumigants. — These are most commonly employed in connection with terminal disinfection. Various proprietary generators are on the market for the liberation of DISINFECTANTS AND DISINFECTION 99 both formaldehyd and sulphur dioxid, but the only advantage that may be credited them is that of convenience. Most of these proprietary formaldehyd generators liberate the gas from paraformaldehyd or paraform, the solid polymer of formaldehyd. (a) Formaldehyd is the most satisfactory fumigant available. Successful results depend upon the rapid liberation of the gas from either formalin, (its 40 per cent, aqueous solution) or solid paraformaldehyd. It accomplishes a surface disinfec- tion and kills spores, though its action on them is slow and uncer- tain. It does not tarnish or corrode metal or bleach pigments. It is not an insecticide. For successful results proper condi- tions of heat and moisture are necessary. The quarters to be Fig. 7. — Flaring top tin bucket for generating formaldehyd by the perman- ganate method. Height 15 inches, diameter 10 inches at base, 15 inches at top of flare. (From Register "Fever Nursing.") disinfected must be maintained at a temperature of '65 degrees F. or higher and the relative humidity must be 60 per cent, or higher. The following methods may be used for its liberation: 1. Spray the formalin upon moistened sheets spread out over stretched lines. Use at least eight ounces of formalin for every 1000 cubic feet in the apartment. One ordinary bed sheet, when previously moistened, will retain this amount of the formalin: The gas is liberated by the evaporation of the water. This is the simplest and cheapest method available. IOO PRACTICAL PREVENTIVE MEDICINE 2. The liberation of formaldehyd by means of potassium permanganate. (a) This method was widely employed when potassium salts were cheap. A deep flaring can, or a large crock or jar is put in a tub in the apartment to be disinfected (Fig. 7). In the crock is placed 250 grams of potassium permanganate for every 1000 cubic feet of space and when preparations are completed there is poured over this 500 c.c. of 40 per cent, formalin diluted with an equal value of water, for every 1000 cubic feet of space. The operator then makes a hasty exit. The crock and tub should not be placed near any draperies and the floor about Fig. 8. — Showing the pot method of burning sulphur. the tub had best be protected by paper. The gas should act for at least 8 hours. (b) Sulphur dioxid is a poorer germicide than formaldehyd, but is a good mammalicide and insecticide. It posesses several disadvantages, namely it tarnishes and corrodes metals, bleaches pigments and rots fabrics. However it is cheap and readily obtainable. The actual disinfection is accomplished by sul- phurous acid, for whose formation water vapor is necessary. Consequently attention must be given to humidity conditions, although moisture is not necessary when it is used as an insec- ticide. For disinfecting purposes 5 pounds of sulphur for every 1000 cubic feet are required. This is equivalent to 5 per DISINFECTANTS AND DISINFECTION IOI cent, of gas, the maximum concentration possible in the air. For every 5 pounds of sulphur employed one pound of water should be vaporized. It is germicidal in from 6 to 24 hours. For the destruction of insects 2 pounds of sulphur per 1000 cubic feet are sufficient. It should act from 2 to 12 hours when used for this purpose. Pig. 9. — For purpose of fumigation all cracks around doors and windows except the door of exit should be sealed with adhesive paper. Sulphur dioxid is most commonly and conveniently generated by the burning of sulphur. Ordinary stick sulphur is crushed to fineness and the required amount is placed in a conical pile in a shallow cast iron pot or jar, which is supported on bricks in a tub containing 1 to 2 inches of water (Fig. 8). A small 102 PRACTICAL PREVENTIVE MEDICINE conical depression is made in the top of the pile and in this is placed a small ball of waste saturated with alcohol. The alcohol is ignited and its burning is sufficient to ignite the sul- phur. It is important that the pots employed be shallow. {c) Preparation oj Quarters jor Fumigation. — All cracks around doors and windows except the door of exit should be Manilla paper ROPE ON INNER side OF PAPER. Fig. ^s UNITED STATES PUBLIC HEALTH SERVICE ■Rope to ground io. — Detail of preparation of window for rapid ventilation after fumigation. {From Trask: Suppl. 15, P. H. Rep.) sealed with adhesive paper, but the lower windows should not be locked (Fig. 9). Open all closet doors and bureau drawers. When the mixture of the reagents is set off, immediately leave by the unsealed door and seal this from the exterior. When the required period of exposure is completed , the ground floor win- dows can be opened from the outside and ventilation estab- lished. The quarters should be thoroughly aired before they DISINFECTANTS AND DISINFECTION 103 are entered. When an entire home or building is to be fumi- gated, ventilation after the completion of fumigation will be facilitated by the sealing of the upper story windows in the manner illustrated in Fig. 10, by which means they can be opened from the ground. 9. Insecticides. — The employment of these will be con- sidered later. REFERENCES Rosenau: Preventive Medicine and Hygiene. 3rd ed. pp. 1099-1176. Practical Use of Disinfectants. Reprint 286, Public Health Reports. Report on an Original Form of Sulphur Burner for Disinfection. Reprint 59, Public Health Reports. Disinfectants: their use and application in the prevention of communicable diseases. Public Health Bulletin 42, U. S. P. H. S. The limitations of formaldehyde gas as a disinfectant. Bulletin 27, Hyg. Lab., U. S. P. H. S. Some common disinfectants. Farmer's Bulletin 926, U. S. Department of Agriculture. Anderson and McClintic: Hyg. Lab. Bulletin 82, U. S. P. H. and M. H. Service. CHAPTER XIII EXCRETA DISPOSAL The term excreta is a collective one, applied to both human feces and urine. These discharges have a direct relationship to health for the following reasons: (a) Several different species of infective agents leave the body by this means, from which they may be transmitted to other persons by the agencies of contact, contamination of water supplies with excreta, and by the contamination of house flies with excreta. (b) In addition, lack of care in the collection and removal of these discharges will give rise to collections of decomposing organic matter about habitations, which are exceedingly offen- sive to the senses. In other words, it then constitutes a nuisance. i. Modern Urban Methods of Excreta Disposal. — The neces- sity for these methods has arisen from the extreme congestion of urban population which characterizes the present era. Ur- ban sewer systems were originally devised for the removal of storm and ground water, not for the removal of excreta. Thus not until 1815 was fecal matter permitted in the London sewers, in 1833 in Boston and in 1880 in Paris. Water closets as we know them, date from the report of tne English Health of Town's Commission in 1844 and were not connected with sewers until 1847. The successful employment of water closets requires that an abundant supply of water under pressure be available, inasmuch as the solid fecal debris is transported in the sewers, particularly the house drains and lateral sewers, by the velocity of the water current. Hence the present system of excreta removal widely employed in our cities and towns is known as the water carriage system. 2. Sewerage. — Sewerage is the term applied to the under- ground system of drains by which excreta is removed inoffen- sively. While the development of such systems has relieved a certain set of sanitary problems by removing these offensive accumulations from around urban dwellings, yet the transporta- tion of the excrement of an entire city without its bounds, and 104 EXCRETA DISPOSAL 105 its concentration at one or a few points has given rise to an entirely new set of problems, which we shall consider later. In a consideration of a sewerage system certain terms are used, which we will define here: (a) A combined sewerage system is one that receives both domestic sewage as well as the surface wash of the streets, known as storm water. (b) Sanitary sewers are those that receive domestic sewage alone. (c) Storm sewers are those that receive storm water or street washings alone. The last two systems are the best where methods of sewage treatment are employed, inasmuch as the large volumes of storm water interfere seriously with the operation of the sewage disposal plants. A sewerage system consists of the following components, the names of which are self explanatory. Starting at the dwell- ings we have the house drains, which discharge into the lateral sewers, which in turn discharge into the trunk sewers, which carry the excreta to the point of disposal. Trunk sewers may be connected to intersecting sewers which carry the excreta still further away. 3. Sewage. — Sewage is the material which flows through the sewers. It consists of the waste water supply, plus ground water leakage into the sewers plus domestic water wastes, plus excreta, plus industrial wastes and perhaps storm water in addition. In dry weather its volume approximates the daily water consumption of the community. Per capita its daily volume in small towns will be from 40 to 50 gallons, in large cities from 100 to 200 gallons. Per capita its average composi- tion will be about the following: Average daily water consumption 285,000 gms. Fecal solids 100 gms. Urinary solids 50 gms. Miscellaneous solids 500 gms. From the standpoint of its composition we may consider sewage to be a more or less homogenous suspension of fine particles with organic and mineral matter in solution. The organic matter present is very unstable so that its chemical composition is variable, depending on the age of the material. Important organic constituents are urea, albumen, fibrin, casein, io6 PRACTICAL PREVENTIVE MEDICINE starch, sugar, fats, and soaps. Of the elemental substances present nitrogen and sulphur are of the greatest importance. 4. Sewage Disposal by Dilution.— The large volume of water present demands that economical transportation be effected by gravity, and that it be discharged into some convenient water course. The discharge of the untreated sewage into some Fig. 11. — Diagram illustrating self-purification in the Thames, England. The discharge of the large volume of sewage from London soon markedly lowers the dissolved oxygen, which however is restored by the time the water reaches the river's estuary. (U. S. Geological Survey, W. S. Paper 185.) water course is known as disposal by dilution. It has given rise to a series of problems, arising from nuisances and the contamination of public water supplies, from which have developed the modern methods of sewage treatment and water purification. If the body of water into which the raw sewage is discharged is of sufficient volume, disposal by dilution may be sufficient. EXCRETA DISPOSAL 107. On the other hand, if the diluting body is of insufficient volume, or if drinking water supplies are contaminated, or oyster beds are contaminated, or a nuisance is produced, it is unsatisfac- tory or even dangerous. When the process is satisfactory the following events take place: (a) There is a sedimentation of the heavy particles. (b) There is an oxidation of the organic matter into stable and inoffensive substances by bacterial activity through the dis- solved oxygen in the water (Fig. n). (c) There is a gradual destruction of the fecal bacteria due to their introduction into an unfavorable environment and the activity of predatory protozoa. Where a stream receives sewage we rind that for a distance of several miles below the sewer outfalls, definite evidence of the sewage contamination is observable, but that at a greater distance the stream bed and 1he water assume an appearance similar to that above the entrance of the sewage and its ap- pearance is no longer offensive. This phenomenon, due to the above agencies, is known as the "self purification" of streams. Where dilution is insufficient we find that the sedimented material and dissolved matter does not undergo oxidation, but, due to insufficient oxygen, undergoes anaerobic decomposition with the production of offensive gases and odors; that the dis- solved oxygen is consumed and fish life cannot survive. Factors which limit the successful operation of this method of disposal are the following: (a) The sewage should not greatly exceed i per cent, of the volume of the water into which it is discharged, though this factor varies directly with the rapidity of the stream, since re- oxygenation is more speedy in rapid streams. (b) The amount of dissolved oxygen in the water, which is greater during cold periods than in warm weather. It must be remembered that the capacity of salt water for dissolved oxy- gen is about 20 per cent, less than fresh water. (c) The rate of the dispersion of the sewage in the diluent. This must be quick. 5. Sewage Treatment. — When satisfactory disposal by dilu- tion cannot be secured, the treatment of the sewage is necessary. The following results are sought: (a) A separation of the suspended matters (sludge) from the liquid sewage. io8 PRACTICAL PREVENTIVE MEDICINE {b) The destruction of the putrescible organic matter in the liquid sewage preparatory to its final mineralization by oxida- tion (non-putrescibility). (c) The transformation of the sludge into a stable and inert condition, with or without the aid of oxidation. (d) The destruction or removal of bacteria from the effluent. Several methods are employed to secure the above results which are used either singlv or in various combinations. Great care and judgement must be employed in selecting the method of treatment to be employed, since different methods of treat- Fig. 12. — Fine mesh revolving screen at Birmingham, England. (Courtesy of J. D. Watson.) These screens constantly revolve so that a fresh surface is always ready for use. (Am. Mus. Nat. Hist., Guide Leaflet, 33.) ment vary in the degree of their successfulness, depending upon the character and composition of the sewage to be treated, as well as the degree of attention paid to the care of the disposal plants. All sewage treatment plants require intelligent opera- tion, together with some degree of skill. Most dissatisfaction or failure can be traced to either neglect or ignorant operation. Sewage treatment plants should be designed by competent sanitary engineers, after study and experimentation has re- vealed the method of treatment best suited to handle the local sewage. EXCRETA DISPOSAL 109 6. Preparatory Processes. — These are designed to effect a separation of the suspended matter or sludge from the liquid sewage. (a) Screening. — Coarse or fine gratings or screens are placed across the path of the sewage to remove coarse material, which is removed from the screens at frequent intervals and either buried or burned (Fig. 12). (b) Sedimentation. — Most of the suspended matter is removed by sedimentation. The velocity of the stream of sewage is lowered and as a consequence the fine suspended particles settle. Various means are employed to apply this principle. Among them are the following: 1. Grit Chambers. — These are small chambers, in which the velocity of the sewage is but slightly reduced, so that only the Pig. 13. — Septic tank or modified sedimentation basin. Photograph of a model in the American Museum. (Am. Mus. Nat. Hist., Guide Leaflet 33.) heavier of the suspended particles settle out. Because of their size the period of sedimentation is brief. They are chiefly used to effect a removal of sand and gravel in combined sewerage systems. These chambers must be cleaned frequently. 2. Plain Settling Tanks. — These are large basins in which the sewage is retained from one to twelve hours. The sludge is removed frequently and is not permitted to undergo decomposi- tion in the tank (Fig. 13). 3. Septic Tanks. — In construction these tanks are similar to the foregoing and differ only in the method of their operation. The low velocity of the sewage in passing through the tank results in its detention for 8 to 24 hours, so that practically all of the suspended matter is deposited. This is permitted no PRACTICAL PREVENTIVE MEDICINE to accumulate at the bottom of the tank for long periods, where, in the absence of free oxygen, it undergoes anaerobic decomposi- tion. As a result of the decomposition the volume of the sludge is very much reduced. Bubbles of gas from the decom- position changes in the sludge, may bring extensive masses of sludge to the surface where it floats as a scum several feet thick. Removal of the sludge is generally only undertaken when such a volume has accumulated so as to seriously reduce the capacity of the tank (Fig. 14). FlG. 14. — Septic tanks, Columbus, Ohio. Twenty million gallons of sewage a day can be treated in this recently constructed plant. (Am. Mus. Nat. Hist., Guide Leaflet 33.) 4. Two Story Digestion Tanks. — Several different designs of digestion tanks belong to this group, of which the best known are the Imhoff tanks. From their construction the sludge is permitted to settle in a lower chamber, where it undergoes anaerobic decomposition out of contact with the fresh flowing sewage. As a consequence the effluent of these tanks is less offensive, and the digestion of the sludge in the lower chamber is more complete (Figs. 15, 16). 5. Chemical Precipitation. — This method is of very limited application and its use is practically limited to those communi- ties where iron wastes in the sewage render the accomplish- EXCRETA DISPOSAL III ment of a precipitating reaction easy. The floculi thus formed enmesh the fine suspended particles and hasten their removal. After the reaction of precipitation has occured, the sewage is Inlet Channel Outlet Weirs Plan Fig. 15. — A digestion tank of the Imhoff type. Section C-C is a longitudinal view and Section D-D is a transverse view. (After Gregory: Engineering Record, I9I5.) Fig. 16. — Twin Imhoff settling tanks at Chambersburg Sewage-Treatment Plant. (Mebus, Engineering Record, 1914.) run into large open tanks for sedimentation to take place. Precipitation is accomplished by the employment of lime, fer- rous sulphate or alum. The principles are similar to the em- 112 PRACTICAL PREVENTIVE MEDICINE ployment of coagulants in water purification which will be spoken of later in more detail. 6. Activation. — In the sedimentation chambers previously described, the decomposition of the sludge is anaerobic in character, offensive gases are produced and the stable sludge finally produced has little value. In the activation process, compressed air is admitted to the tanks through porous plates in the bottom, and as a consequence aerobic processes of decom- position are facilitated. The sludge is rapidly oxidized, is non- offensive and has considerable value as a fertilizer (Fig. 17). Fig. 17. — Air-diffusers in sloping bottom of activated sludge tank. {Engineering Record, 191 5.) 7. Roughing Filters. — These are large vats or tanks filled with coke, crushed stone, or similar material, and filled with sewage. As a consequence of the rock or other inert material present, sedimentation is facilitated, since the vertical distance a sus- pended particle has to pass to reach a firm support is very much reduced. 7. Sludge Disposal. — The amount of suspended matter collected in the tanks is considerable and since (except in that collected in the activation process), its value is slight or nothing, the disposal of sludge is usually considerable of a task and a problem. Digestion measures considerably reduce the volume to be disposed of, but do not altogether dispose of the sludge. The following additional measures are employed: (a) Pressing the sludge in filter presses to remove the surplus EXCRETA DISPOSAL 113 moisture. This is necessary to permit its ready handling. After a drier sludge is secured it is either : (b) Used for filling low areas of land, or (c). Loaded onto cars, or barges and dumped at sea. (d) Some of the more stable sludges, for example those secured from the Imhoff tanks, are run off into drying beds. When dry the sludge is of loamy consistency and is then scraped off and buried in trenches. CHAPTER XIV EXCRETA DISPOSAL (CONTINUED) 8. Purification Processes. — These processes are designed to treat the effluent from the various types of sedimentation basins to secure a stable effluent, that is, one which is not subject to further decomposition changes. Where satisfactory most of the nitrogen will have been changed to nitrates. All depend upon active oxidation, which is secured by microbial activities. The following methods are employed to secure this result : Fig. 18. — Intermittent sand filter bed. Photograph of a model in the American Museum. (Am. Mus. Nat. Hist. Guide Leaflet 33.) {a) Subsurjace Irrigation. — The effluent is intermittently dis- charged through one or more strings of open joint tile just under the surface of the ground. The liquid is thus discharged into the layer of soil where bacterial activities are greatest. The method is only adapted to open or porous soils, particularly under rural conditions where the volume of liquid is small. (Figs. 26 and 27). The soil must not be permitted to become water logged, otherwise aerobic decomposition will be super- seded by anaerobic, and a nuisance result. 114 1 EXCRETA DISPOSAL "5 (b) Broad Irrigation. — The sewage effluent is discharged into irrigation furrows on cultivated land and permitted to percolate downward through the soil. This method is only adapted to open or porous soils, preferably in arid regions, where water for purposes of irrigation is at a premium. Under these circumstances it may pay for itself. It has not been a success in this country. (c) Intermittent Sand Filtration. — The effluent is applied in- termittently, soaks quickly away and most of the time the filter is exposed to the air. With proper operation very good results are secured. On the other hand, if too large quantities of effluent are applied, or applied too frequently, the filter be- comes water logged and oxidation is prevented. Its use is, Fig. 19. — Double contact beds for purification of sewage. Photograph of a model in the American Museum. {Am. Mus. Nat. Hist. Guide Leaflet 33.) practically limited to areas of sandy soil. These should, be ridged for winter operation to prevent freezing (Fig. 18). (d) Contact Beds. — These are similar in construction to roughing niters, but are operated int ermittently on the fill and draw method. The suspended matter settles on the crushed stone. When the tanks or beds are full the action is septic or anaerobic, when empty the matter on the stone is subjected to aerobic or oxidative action. The beds are usually operated in series (Fig. 19). (e) Trickling Filters. — These are concrete vats, on the floor of which are open tile drains, and above which are several feet of crushed rock, over which the sewage effluent is sprinkled or sprayed. The interstices of the rock are exposed to the air at all times when properly operated. As a consequence com- n6 PRACTICAL PREVENTIVE MEDICINE plete aeration is secured and the effluent is stable. They are well adapted to areas where sandy soil is not available (Fig. 20). 9. Finishing Processes. — In the first three methods de- scribed above, the filtered effluent joins the ground water. In the latter two it is discharged from the beds into some water course. In order to destroy any pathogenic bacteria which have managed to pass through the treatment beds, the present practice is to sterilize the effluent by the employment of chlorine, either as compressed chlorine or bleach. The methods of application are similar to those used in water disinfection r • w " ~""~~ ^^^ : -— lAhUhllii lit ili 1 if •' — '-^fj ■■■' -*-f--M-rTT" a s ww ww w^'^rw'^fytt Pig. 20. — Trickling filters, Columbus, Ohio. By means of fixed sprinkler nozzles, sewage is sprayed evenly over the surface of a bed of coarse stone. This method is at present considered one of the most effective of all devices for sewage purification. {Am. Mus. Nat. Hist. Guide Leaflet 33.) where they will be discussed in more detail. The quantity applied varies with the condition of the effluent. It is also applied to raw or unsettled sewage where other treatment is not used. 10. Domestic Excreta Disposal. — We will now consider the methods of excreta disposal available for isolated dwellings, for example those in unsewered portions of cities and towns, unsewered villages, farm homes, summer resorts, and camps. It is essential that individuals under these circumstances be sufficiently educated in personal hygiene to realize the impor- tance (1) of having som-? place about the dwelling where the EXCRETA DISPOSAL 117 excreta of all members of the household is concentrated, (2) that at the place of concentration the excreta is so cared for that it is not a further menace to their health, and (3) that modesty, decency, and cleanliness, are cultivated. Only where these are observed can soil pollution or contamination by ex- creta be prevented (Figs. 21, 22), and domestic water supplies be safeguarded. The methods suitable to any given home will depend whether or not domestic water pressure is available. In the absence LH yiicoEf^. Pig. 21. — An unsanitary privy of primitive type permitting extensive soil pollu- tion. Drawn from a photograph. (P. H. Bull. 68. U. S. P. H. S.) of domestic water pressure either of the two following methods may be employed: (a) The So-called Chemical Closets. — These are simple in- stallations for the interior of the dwelling, in which the excreta is received into a strong caustic solution, which disinfects the material. If properly cared for they will probably give satis- factory results (Fig. 23). (b) Privies. — A satisfactory privy should protect the excreta from flies, rats, hens, pigs, etc., and should be well ventilated to permit the ready evaporation of the liquid excreta. Their II< PRACTICAL PREVENTIVE MEDICINE Fig. 22. — Typically unsanitary privy at a farm home, showing flies swarming about the privy contents. The excreta are deposited upon the surface of the ground. (Lumsden: P. H. Bull. 94. U. S. P. H. S.) AWl M/CXC17 00V fVAM W Pig. 23. — Sketch showing general arrangement of a chemical closet. (Cour- tesy of the Dail Steel Products Company.) (Hansen: Illinois Health News.) EXCRETA DISPOSAL 119 successful operation depends upon the degree of simplicity in their construction, as a general proposition those whose success- ful operation requires continuous care are neglected sooner or later. All should be well screened and have a tight seat cover. Privies are usually of the following types: 1. Vaulted. — The excreta are deposited into a pit or vault underneath. The pit should be made water tight by means of concrete walls and bottom (Fig. 24). 2. Pail or Can Privies. — The excreta are deposited in large pails or buckets fitted underneath the seat. At voiding the person using the privy may cover the excreta with a thin layer of dry earth or ashes. Thev require constant attention, are apt to be Fig. 24. — A stationary-receptacle sanitary privy- with a cement vault arranged for convenient clearing. (P. H. Bull. 68, U. S. P. H. S.) neglected and hence, if privately controlled, are troublesome (Fig. 25). The wide spread employment of this type of privy- in unsewered towns, or unsewered areas of towns, should be under municipal supervision. Provision should be made for the ex- change of receptacles at frequent, regular intervals, if satisfac- tory results are to be secured. The expense of maintainence of such a system is high, which tends to stimulate a desire for the early installation of a sewerage system. The excreta (or night soil) are disposed of either by burial or incineration. 3. Leaching Privies. — These are apt to be unsatisfactory or dangerous. No pit is provided and the excreta are deposited on the surface of the ground. They should be located with care 120 PRACTICAL PREVENTIVE MEDICINE with particular reference to surface drainage and are not suit- able for clay, gravely soil or limestone soils. They are not to be recommended. When domestic water pressure is available cess-pools are commonly employed. The closet is located within the house EXCRETA DISPOSAL 121 h ,Siudge Outlet Sludge Outh Sub-Surfoce Drain' SUGGESTIVE DESIGN FOE« SEWAGE TANK WITH DOSING GHAMBEB DISCHARGING INTO A DBAIN TILE SUB-SUPFflCE DISPOSAL SYSTEM SCALE in FEET Pig. 26. — Simple form of tank built in conjunction with a dosing chamber for applying the sewage in doses on secondary treatment devices, suitable for domestic installation. See Pig. 27. (After Hansen: Illinois Health News.) Pig. 27. — Typical plan for a subsurface sewage disposal system for domestic installation. (After Hansen: Illinois Health News.) 122 PRACTICAL PREVENTIVE MEDICINE and water carriage is employed to transport the excreta to the point of disposal. These are of two main types: (a) Vaulted Cesspools. — These have concrete bottoms, sides and top, and are in reality septic tanks. The sludge should be burned, buried, or disinfected, while the effluent is best dis- posed of by subsurface irrigation (Figs. 26, 27). Roricultural drain tile pipe \y5Mpsof far paper V laid aw tops of joints Hollow brick /aid radially ^Manhole frame and cover /-?/ / / A 1 o-a | a □ □ □ a d IAi /lap DD a°l//J |aa| ao an □ □ |/ |QD dd aaj/ De+aita of Hollow Bric/% Pig. 28. — Hollow brick cesspool of the leaching type with overflow into agri- cultural tile. (Horton: N. Y. State Dep't. Health.) (b) Leaching Cesspools. — These do not have either a light bottom or walls. The liquid contents escape into the soil below the zone of active oxidation and hence may contaminate the ground water for some distance. They should not be used in clay or gravely soils or in limestone regions (Fig. 28). REFERENCES Rosenau: Preventive Medicine and Hygiene, 3rd Ed., Sewage Disposal, by George C. Whipple, Sec. VII, pp. 955-979. Daniels: The Operation of Sewage Disposal Plants. Lumsden: A Sanitary Privy System for Unsewered Towns and Villages. Public Health Bulletin No. 89. U. S. P. H. S. EXCRETA DISPOSAL 123 Hansen: Disposal of Sewage from Country Homes, Small Institutions and Country Clubs. Illinois Health News. Aug., 1916. Published by 111. State Board of Health. Horton: The disposal of human excreta and sewage of the country home. New York State Department of Health. Faber: The operation and care of sewage disposal plants. Bulletin 16. Engineering Extension Department. Iowa State College, Ames. The treatment of sewage from single houses and small communities. Reprint 506, Public Health Reports. Chemical closets. Reprint 404, Public Health Reports. See also various water supply papers of the U. S. Geological Survey. CHAPTER XV THE RELATIONSHIP OF WATER TO HEALTH AND DISEASE While water is not technically a food, it is an essential article of the diet. In addition it bears an important relationship to personal hygiene, inasmuch as it is essential in the maintenance of proper cleanliness of the person, the clothing and other objects. 1. Relationship to Health and Disease. — The body requires an adequate daily supply for its physiologic uses. The amount required by the male adult represents the maximum consump- tion for this purpose, varying from 1800 to 2100 c.c. of water ingested as such, with approximately 600 c.c. additional ingested with the solid food. Water bears an important relationship to the communicable diseases, as it may be an important route in the transmission of several species of infective agents. The properties which make it important in this connection are the following: (a) It is ordinarily consumed raw, i.e., it has not been heated or otherwise subjected to any treatment that will destroy any infective agents present. (b) In its normal cycle of circulation it comes in contact with a great variety of material spread over vast areas, hence if ex- creta be present in the open, they will be transported, together with infective agents present, by the water. Furthermore m any natural sources of water supply are frequently contaminated, very often grossly so, by the direct discharge of sewage. Water also serves as a solvent for certain inorganic poisons. 2. Conditions which Favor the Contamination of Water and the Transfer of Infective Agents. — Of the relationship of water to disease, that in connection with the transfer of infective agents is of greatest importance. The following conditions render the employment of a contaminated and infected water possible and probable: (a) The use of water which receives the sewage of other towns; the sewage of the same town, the sewage of individual 124 RELATIONSHIP OF WATER TO HEALTH AND DISEASE 1 25 houses, institutions or factories, or the presence of privies on or over a stream. {b) The rush of floods or heavy rains which transport excreta deposited on the surface of the ground into a water course. (c) The use of double supplies coupled together, one for ordi- nary domestic consumption, the other from an unsafe source for emergency fire protection. (d) Contamination of a water shed from labor camps, rail- road coaches, or excursionists. The following factors influence the transfer of infective agents by water: (a) The quick transfer of infective agents from one patient (source) to the victim in the person of the consumer. (b) The probabilities favor the short survival of infective agents in water, and in addition their multiplication in water is doubtful. (c) Cold wa ter tends to prolong the period of their survival. \d) The proportion of infective excreta to the volume of the diluting water is usually very small, so the dilution of the micro- organisms is enormous. (e) Surface water supplies, which are most exposed to fecal contamination, are most frequently infected, while wells and springs are less often. The foregoing factors have given water borne epidemics cer- tain definite characteristics among which the following are the most conspicuous: (a) Epidemics occur most frequently, and endemic water borne typhoid reaches a maximum during the seasonal periods (winter, fall, spring) when the water is coldest. (b) Water borne epidemics have an abrupt onset, rise rapidly to a maximum and rapidly decline, i.e., they are explosive. (c) Investigation usually succeeds in revealing a nearby con- tamination and frequently the actual source or sources of in- fection. (d) Present day evidence only indicates that water plays a role in the transmission of those infective agents which leave the body in the feces and urine, for example, typhoid, cholera, and bacillary dysentery. Indirectly water is of importance as a breeding place for certain insects, such as mosquitoes, concerned in the transmis- sion of other infective agents. 3. Inorganic Poisoning from Water. — Lead poisoning from water is not unknown. Lead is not found in natural water, 126 PRACTICAL PREVENTIVE MEDICINE and when present is derived from the lead service pipes or some other lead object connected with the supply. The plumbo- solvent power of water depends upon the following factors: (a) The presence of a free acid, such as carbonic acid, which is found in soft peaty waters, or, ; (b) The presence of an excess of oxygen and little dissolved matter, such as soft water, or, (c) The presence of organic matter, nitrates or nitrites, or (d) The presence of chlorides, which exert a solvent power on the film of the lead carbonate coating the pipe. The following conditions also affect the solvent power in direct proportion: the duration of contact; the temperature; the pressure; and the purity of the lead. In general one may say that turbid and hard waters have the least plumbo-solvent power. In the new England States lead poisoning from this source is a problem to be constantly borne in mind and is usually overcome* by using brass pipes instead of lead pipes. 4. Source of Water Supply. — Water is practically derived from three sources : (a) Rain water, which is the ultimate source of all water. Practically it is of domestic importance only, in the United States. If care and attention are directed to the following points a satisfactory supply will be secured: (1) The material and care of the collecting surface; (2) Wastage of the first flow, and (3) Location and construction of the storage cistern. (b) Surjace water, including the water of streams, lakes, and impounding reservoirs. Such water is greatly exposed to con- tamination and its dissolved as well as suspended matter is very variable in amount. Surface water is widely utilized as a source for municipal supplies because of the vast amount available. (c) Ground water, including the water from wells and springs. In its underground passage this water is usually subjected to a varying degree of natural filtration and is less subject to contamination. It is of importance as both a domestic and municipal source of supply. 5. The Hygienic Examination of Water. — Valuable informa- tion concerning the past history of water from a given source of supply, and hence of its hygienic value, can be secured by a physical, chemical and bacterial examination. Of still greater value than such an examination however, is a thorough inspec- tion of the source of the supply by one competent to judge pos- sible sources of contamination. Laboratory examinations RELATIONSHIP OF WATER TO HEALTH AND DISEASE I 27 should be supplemental to such surveys. The following fea- tures are usually considered in a laboratory examination of water because of their direct or indirect bearing upon health: (a) Odors. — These are in themselves harmless, but because of their offensive character result in complaints, and a lessened consumption of water. They are due to volatile essential oils liberated from the bodies of microscopic green plants (algae), and are usually most pronounced in stagnant water containing very little or no dissolved oxygen. (b) Taste is derived from matter in solution, either mineral or gaseous. It may render a supply unpalatable. (c) Color is of vegetable origin and is due to material in solution. (d) Turbidity is due to material in suspension, the water is said to be muddy. It may, if excessive, result in a lessened consumption of the water. (e) Reaction. — The reaction of water is normally alkaline, due to the carbonates and bicarbonates of calcium and mag- nesium in solution. Acid waters are rare, and usually owe their acidity to either trade or mine wastes, though swamp waters may be normally acid. (/) Total Solids. — The amount of dissolved matter in water varies widely. Quantities in excess of 500 parts per million are commonly considered to render the water unfit for use. (g) Hardness is either temporary or permanent. Temporary hardness is due to the carbonates or bicarbonates of calcium or magnesium, while permanent hardness is due to the chlorides or sulphates of calcium or magnesium. The importance of hardness is economic, inasmuch as hard waters require a much greater amount of soap to make them suitable for wash- ing purposes than do soft waters. (h) Organic matter is of itself of doubtful importance, al- though some outbreaks of diarrhea have been ascribed to the presence of toxic substances of putrefactive origin. Ordinarily the chemical examination ascertains the scope of the changes which the nitrogenous compounds have undergone, as indicating something of the changes which have taken place in dissolved organic matter. The determination of nitrates and nitrites is considered of greatest importance. The nitrites (N0 2 ) sug- gest recent organic pollution, though if present in small quan- tities, their significance is slight. The nitrates (N0 3 ) suggest past or distant pollution. Chlorine suggests remote urinary contamination, though in interpreting these results one must 128 PRACTICAL PREVENTIVE MEDICINE bear in mind the so-called normal chlorine, i.e., the chlorine normally present in water, which is derived from sea spray or salt deposits. (i) Bacterial. — From a hygienic standpoint the information secured by a bacterial examination of water is probably of greatest assistance and hence of greater value than any other determination. Unfortunately, since the sources vary so widely, it is impossible to establish numerical standards of the number of bacteria permissible. The greatest value of the numerical determination of bacteria in water is in the study of surface waters or in the control of purification plants. The detection of fecal bacteria is of greatest hygienic value since they give evidence of recent contamination. The group of colon- like bacilli are the chief ones sought. Their detection in ground water is of great significance, while in surface waters in quanti- ties less than i per c.c, their significance is slight. Owing to their extreme dilution and for other reasons the detection of specific pathogenic organisms in water is not practicable. The detection of bacteria characteristic of feces indicates that fecal contamination is occurring, which also indicates that the ex- creta from an individual discharging specific infective agents might as easily gain introduction. It is impossible to form an accurate idea of the hygienic character of a water supply from single isolated examinations. The character of raw natural waters, particularly surface waters, is subject to considerable fluctuation, while the operations of a water purification plant can only be accurately controlled by frequent routine examinations of the water. Fur- thermore, contamination of a supply deemed to be above suspicion may actually occur, and unless its quality is regularly followed by laboratory examination, an epidemic may be the first indication of an unnoted contamination. Such periodic routine examinations should be at least daily at water purifi- cation plants, and with untreated water from satisfactory sources, at not less than weekly intervals. A rigid bacterial standard for potable waters is the Treasury Department standard for water furnished common carriers in interstate traffic. It is as follows : (a) The total bacteria per cubic centimeter shall not exceed ioo, when inoculated into standard agar and incubated at 37 degrees C. for 24 hours. (b) Not more than one out of five, 10 c.c. portions of any sample shall show the colon bacillus. RELATIONSHIP OF WATER TO HEALTH AND DISEASE I 29 A water that meets these requirements is probably from a satisfactory source, but on the other hand, the standard is so rigid that water from many safe sources of supply would be excluded. The following are suggested by Bartow as the permissible limits for impurities in Illinois waters, expressed in parts per million (P.P.M). TABLE IV Characteristic Lake Michigan Streams (Fil- tered) Springs and shallow wells Deep drift wells None IO. *None *None None O. 2 *None *None None None None None 150.0 300.0 500.0 500.0 4-5 6.0 150 150 0.01 0.05 0.02 0.02-3 0.08 015 0.05 0.20 0.04 °-5 2.0 0.5 None None None 0.005 100 500 500 100 Absent Absent Absent Absent Deep rock wells Turbidity Color Odor Residue on evaporation Chlorine N as free ammonia N as albuminoid ammonia. . . N as nitrates N as nitrates Bacteria per 1 c.c. 2o°C Colon bacillus *None *None None 500.0 5 .0-100 0.02-3 0.15 °-5 0.000 100 Absent None as drawn, developes on standing. 6. Water Consumption. — The water consumption in cities where a municipal supply is available under pressure in the majority of dwellings, when considered on a per capita basis is quite variable, ranging from 25 to 370 gallons and perhaps averaging somewhere near 120 gallons per capita per day. It is ordinarily considered, that per capita, common domestic uses require from ten to seventeen gallons daily. The difference in the above figures is due to the use of water in manufacturing, irrigation, and losses by wastage. In European cities the per capita consumption is much lower, varying from 24 to 69 in a number of larger cities, and perhaps averaging about 40 gallons. These figures probably represent an unduly low con- sumption of water, but on the other hand, the American figures undoubtedly represent a serious waste of this indespensible necessity. Our aim should be to encourage a generous use of water, but to discourage waste. 9 130 PRACTICAL PREVENTIVE MEDICINE REFERENCES Standard Mthods of Water Analysis. Am. Pub. Health Ass'n., 191 7. Hazen: Clean Water and How to get it. Rosenau: Perventive Medicine and Hygiene. 3rd. Ed., pp. 912-954. pp. 789-877. Sewage Pollution of Streams. Reprint 362, Public Health Reports. See also the list of water supply papers of tee U. S. Geological Survey. CHAPTER XVI WATER PURIFICATION i. The undesirable qualities which water may possess and the means available for their removal are presented in the following table: Undesirable quality Removal for industria uses Removal for domestic uses {a) Hardness. i. Temporary Lime and soda ash; mutit. per- Boiling or soap. 2. Permanent. Lime and soda ash; per- Lime and soda ash; per- mutit ; distillation and mutit; distillation and condensation. condensation. (b) Undesirable metals. I. Iron Precipitation with lime and rapid sand infiltra- tion. Aeration. 2. Lead Neutralization with lime and filtration. (c) Odors and tastes (Al- gal) (see Fig. 30) Coagulation and Aeration. (d) Color rapid Coagulation and rapid sand nitration. sand filtration. (e) Turbidity Sedimentation, coagula- Coagulation and rapid tion and rapid sand sand filtration. filtration. (/) Bacterial removal. . . . Storage; sedimentation; rapid and slow sand fil- tration; domestic niters. (g) Bacterial destruction. Boiling; use of bleach; chlorine; and ultra-violet light. (h) Algal destruction (see , Fig. 29) Copper sulphate. Owing to limitations of time and space we will not give fur- ther consideration to the methods for the removal of hardness or undesirable metals, but only consider the others. 131 132 PRACTICAL PREVENTIVE MEDICINE 2. Storage. — The storage of water in large impounding reser- voirs or lakes for several months effects a removal of any in- Fig. 29. — Applying copper sulphate for the destruction of algae at St. Paul. Note the bag containing the copper hung over the stern of the boat. {Huff and House, Jour. Am. W. W. Ass'n., 1916.) Fig. 30. — Aeration of Hemlock Lake water at Rochester, N. Y., resulting in a reduction of tastes and odors. (Courtesy of Mr. Emit Kuichling.) fective agents present, by their exposure to an unfavorable en- vironment. We have already called attention to the fact that the survival of pathogenic micro-organisms in water is but for WATER PURIFICATION *33 a short period. They are exposed to the direct action of the sun's rays and they are devoured by predatory organisms, of which the infusoria are probably the most important. One months storage under these circumstances will result in their destruction. The greatest drawback to the employment of this method is the fact that sufficient space in the shape of a reservoir is frequently not available so as to permit a city to store a month's supply, or else a sufficient reserve of water is not available to permit its aging for a month before consumption (Fig. 31). 3. Sedimentation. — The lowering of the velocity of a stream, such as that effected when it enters a lake or reservoir, permits the fine suspended particles to settle to the bottom. The finer the particles, the lower must be the velocity and the longer the Fig. 31. — Lake Cheesman dam and reservoir. Denver Union Water Com- pany. A large impounding and storage reservoir. (Hazen: "Clean Water and How to Get It," John Wiley and Sons.) quiescent period before their removal is effected. This method in itself is used chiefly as a means of removing turbidity, and is of but slight value in the removal of bacteria unless the period of quiescence approximates the conditions of storage. Large open tanks or reservoirs are employed for sedimentation. Sedimentation maybe employed in conjunction with the process of coagulation. 4. Coagulation is used in conjunction with sedimentation or as a process of treatment preliminary to rapid sand filtration. It is a necessary measure to remove the fine turbidity, parti- cularly that produced by colloidal clay, which would not completely settle out no matter how long the period of sedi- mentation. Coagulation consists in the employment of cer- 134 PRACTICAL PREVENTIVE MEDICINE tain chemicals, such as sulphate of aluminum, which react with the alkaline carbonates of the water to form aluminum hydrate. This has a large colloidal molecule and being in- FiG. 32. — Sedimentation and coagulation basins at Louisville. Note the iong vertical partitions or baffles which reduce the velocity of the water in passing through the basins. (Water-supply Paper 315, U. S. Geological Survey.) soluble, is thrown out of solution as a coarse, flocculent pre- cipitate in which most of the suspended matter and bacteria become enmeshed (Fig. 32). WATER PURIFICATION 135 In practice only sufficient alum is added to combine with the carbonates, so that no alum remains in solution and all of the precipitate is removed (Fig. 40). Iron sulphate is similarly used. If sufficient carbonates to break up the alum are not present normally, the required alkalinity is secured by the addition of lime or soda to the water. 5. Slow Sand Filtration. — This is accomplished by large filters, either open or covered, each about an acre in extent (Fig. 33) consisting of collecting tiles overlain with gravel and 1 Fig. 33. — Bird's eye view of the covered slow sand filters at Providence showing the pumping station, laboratory, filter roofs and the storage of dirty sand. (1910 Rep. Providence City Engineer.) coarse sand (Fig. 34). These are operated with ahead of from two to four feet of water above the sand (Fig. 35). Bacterial removal is not accomplished by any straining action of the sand grains, but by the development of algse and protozoa in the surface layers of the sand, which reduce the interstices still further and prey upon bacteria. When this biological film is sufficiently developed the water passing a filter is used. Under these conditions it is so operated as to permit the passage of from 2.5 to 5 million gallons of water per acre per day. The biological film continues to develop during the course of several 136 PRACTICAL PREVENTIVE MEDICINE weeks to such an extent that the passage of water gradually becomes seriously hindered, whereupon the filter is drained, and the top layer of sand is removed (Fig. 36). After cleaning, the filter is again placed in commission and the process of cleaning is repeated as often as necessary. When the sand layer is re- duced to 12 to 18 inches in depth, the filter is drained and the sand, which in the meantime has been washed, is restored to the filter (Fig. 37). Preliminary methods of treatment are not required, although the process is not adapted to turbid water. The first cost of 43 iltf*** ..••■■■ iiia- - * 1- m** «.*•*" ,«*»«« a,*,**'*^ Fig. 34. — Cross-section of a typical slow sand filter. Note the under drains, which are of an uncommon type, the layer of superimposed gravel, and the thick layer of coarse sand. (Mason, " Water Supply," John Wiley and Sons.) installing such a filter plant is large, but the operating cost is low. The filter accomplishes a bacterial removal of about 99 per cent, and is extremely uniform in its action. 6. Rapid Sand Filtration. — -This is accomplished by two types of filters, either pressure or gravity, according to the manner in which the head of water is secured upon the filter. The operation of each is based upon the same principle. This method requires only a small installation, with a low initial cost, but a high cost of maintenance. They are very efficient WATER PURIFICATION J 37 in the removal of color and turbidity, and slightly less efficient (95 per cent, to 99 per cent.) and less uniform in the degree of bacterial removal secured as compared with slow sand niters. Filtration is effected by the formation of a thin film of the precipitated coagulant upon the surface of the sand through which the water passes, either by gravity or pressure. Since the film of precipitate held back by the sand is constantly increasing, the amount of water which passes through is soon finally reduced below efficient limits. When this occurs, usually every 6 to 12 hours, the filter is disconnected and the precipi- FiG. 35. — Filter bed No. 6, Indianapolis Water Company. This illustration shows the smooth, clean surface of the sand in a filter bed which is ready for water to be admitted. The water covers the sand to a depth of about four feet. tate removed by reversing the flow of water, and agitating the sand, either by means of compressed air or mechanical rakes (Figs. 39, 42). The dirty wash water is wasted. When the sand is cleaned, the reverse flow is stopped, the sand settles into place over the gravel, and the coagulant containing water is again sent through the filter. These filters are operated at the rate of ioo to 150 million gallons per acre per day, hence the small installations. Sedimentation to remove some of the precipitated coagulant 138 PRACTICAL PREVENTIVE MEDICINE is usually used as a preliminary process, in order to prevent the too rapid clogging of the filters. The gravity filters are open vats or reservoirs or wood or con- crete (Fig. 41), while the pressure filters are cylindrical steel tanks (Figs. 38, 39). 7. Disinfection of Water. — In this country chlorine is the only agent extensively employed for this purpose, and is ap- plied either as liquid chlorine or a solution of bleaching powder. Disinfection is applied as a finishing process to water that has Pig. 36. — Filter bed No. i, Indianapolis Water Company. This shows work- men cleaning or scraping a filter bed to remove the muddy upper layer of sand containing the impurities trom the water. The sand is thrown into piles previous to being removed for washing. been previously filtered or otherwise clarified. The value of the process from the standpoint of the destruction of the bac- teria which pass through the filters, including pathogenic and non-pathogenic germs, has been well demonstrated. From .1 to .5 parts per million of available chlorine are commonly em- ployed, requiring the addition of about 5 to 12 pounds of bleach per million gallons of water. Quantities of bleach in excess of 25 pounds can be detected by taste. Of recent years the employ- ment of liquid chlorine has been superseding bleach, owing to the lesser cost of the former, as well as its convenience (Fig. 43) . The WATER PURIFICATION J 39 '1 Fig. 37. — Sand washing machine, Indianapolis Water Company. Sand being removed from filter bed, washed and stored by hydraulic machinery. Fig. 38. — Mechanical filters at Chattanooga, Tenn. Note the vertical shafts at the top of each pressure filter unit. To these shafts are connected the revolv- ing rakes which agitate the sand when the filter is washed. The shafting re- volves the rakes. It is because of these connections that pressure filters are sometimes called mechanical filters. (Courtesy of American Water Works and Guarantee Company.) 140 PRACTICAL PREVENTIVE MEDICINE Pig. 39. -Schematic view of a typical rapid sand filter of the pressure type. (Mason, "Water Supply," John Wiley and Sons.) L Fig. 40. — Coagulant storage and feeding devices at Scranton. The coagu- lant solutions are stored in the tanks on the platform, and fed into the raw water by means of the constant head device on the floor below. (Water Supply Paper 315. U. S. Geological Survey.) WATER PURIFICATION 141 amount required is greater when the content of the water in organic matter is high. Disinfection is probably accomplished Fig. 41. — Interior of the gravity type filter house at Little Falls. The filter units are observed beyond the railing at either side. The operation of each filter unit is controlled by means of electrically operated valves, manipulated from the table in front of each filter. (Courtesy of Mr. G. W. Fuller.) Fig. 42. — A gravity filter unit at Watertown, N. Y., with the sand and gravel removed. Note the strainers and piping for collecting the filtered water, the pipes for the compressed air used to agitate the sand in washing, and the wooden troughs at the top, which carry the waste wash water away. (Hazen: "Clean Water and How to Get It," John Wiley and Sons.) by nascent oxygen liberated by the hypochlorous acid formed by the mixture of the bleach with the water. 142 PRACTICAL PREVENTIVE MEDICINE MANUAL CONTROL CHLORINATOR SOLUTION FEED - TYPE >S, Fig. 43. — Photograph and diagram of a typical device for the disinfection of water by liquid chlorine. (Wallace and Tiernan Co., New York.) I, Chlorine absorption chamber; K—L, chlorine solution line; V, water con- nection; P, water valve; R, gauge; O, water valve to water seal N; T, water spill; U, chlorine solution line to point of application; N, water seal; Size, apparatus mounted in wall cabinet 20 X 21 inches; S, control valve; A, chlorine tank; B, valve on chlorine tank; C, auxiliary valve; D, flexible connection; E, pressure compensating valve for taking care of the varying pressures in the chlorine tank and also maintaining a constant drop in pressure across the valve 5; S, control valve; G, valve to prevent moisture from getting back into control parts of apparatus; H, valve to control flow of water and to keep chlorine out of incoming water connections; F, pressure gauge showing pressure in tank; J, chlorine flow meter (inverted siphon type). WATER PURIFICATION 143 8. Results of Water Purification and Disinfection. — Since the first serious . attempt at water purification in the United States in 1872, the practice has abundantly justified itself as a sanitary measure of the highest order. Endemic water borne typhoid has either been eliminated or greatly reduced in the municipalities making the change. In Table V are presented a few examples to show the typical results which have been secured. TABLE V Effect of Water Purification on Typhoid Rates. Average Typhoid Death Rate per 100,000 Population (After Rosenau). City Average before improvement Average after improvement Percentage reduction Albany Elmira Hudson Ithaca Schenectady. Troy Watertown. . , Binghampton Rensselaer. . . . 23-7 4i-5 3i-9 14.6 14.4 31.0 36.9 11. 7 54-4 73-° 24.4 5°-5 78.3 42 .6 46.8 61.8 72.3 43 -o TABLE VI Effect of Chlorination on Typhoid Rates. Average Typhoid Death Rate per 100,000 Population (After Race) Chlorination begun Before using After using Percentage City Period Rate Period Rate reduction Baltimore Cleveland Des Moinss Erie June, 1911 Sept., 1911 Dec, 1910 March, 1911 Dec, 1911 Sept., 1908 Jan., 1911 May, 1910 Dec, 1911 Feb., 1910 April, 191 1 Sept., 1912 1900-10 1900-IO 1905-10 1906-10 1 908- 1 1 1900-17 1900-10 1900-09 1907-H 1906-10 1906-IO 1906-10 35-2 35-5 22 . 7 50.6 29.0 18.7 42.5 22.5 46.0 40.0 31.2 34 -° 1912-15 1912-16 1911-13 1912-14 1912-13 1909-16 1911-16 1911-16 1911-14 1911-16 1912-16 1913-17 22 . 2 8.2 13-4 15.0 14-5 8.4 14.2 10.6 28.7 25.0 7.8 17.0 36 77 41 70 Evanston, 111 Jersey City Kansas City, Mo. Omaha, Neb Trenton 5° SS 66 53 35 Montreal Toronto 37 75 Ottawa 50 144 PRACTICAL PREVENTIVE MEDICINE Though a much more recent development, the reduction in typhoid rates effected by chlorination of water are every bit as striking as those secured by purification. The experience of a few cities is summarized in Table VI. TABLE VII Typhoid Fever in Burlington, Vermont Year Death rates per 100,000 from typhoid fever, 1904 36 I90S 34 1906 43 1907 23 1908 20 (Mechanical filter plant opened in April). 1909 25 1910 n (Bleach applied to water in April). 1911 7 1912 4 Evidence is accumulating to indicate that purification in itself did not succeed in completely eliminating water borne typhoid. Cities which experienced a reduction in their typhoid rates following the installation of a purification plant experi- enced a still further reduction after the inauguration of dis- infection. An example of this experience is shown in Table VII. In addition, several instances have been observed of typhoid and dysentery outbreaks following emergencies when purifica- tion plants were temporarily shut down because of floods or accidents. In addition to affecting a reduction in the typhoid death rate, Mills and Reincke noted (Mills-Reincke phenomenon) that following the improvement in a water supply by the introduc- tion of purification processes, there is not only a drop in the typhoid death rate, but a drop in the general death rate as well. From studies by McLaughlin it would appear this decline is due to a decrease in infantile deaths from diarrhea. The type of purification process or processes best adapted to a given source of water supply, as well as the source of a con- templated municipal supply itself, had best be selected by competent sanitary engineers after careful study has been made of the source, its probable ability to supply the demands of a growing population for the next twenty or thirty years and the character of the impurities whose removal is necessary. WATER PURIFICATION 145 9. Domestic Water Supplies (Figs. 44, 45, 46, 47). — These include wells, springs, and cisterns. It is important to remember that with these the danger of contamination is practically exclusively from surfaces sources. They should therefore be protected from surface drainage, and have tight water-proof tops. They should also be located a considerable distance WATE.R BEARING ■V-'.'SAND Fig. 44. — Showing how pollution may enter an improperly located and poorly constructed well. Most contamination of wells enters from the top. Note the drainage toward the well. {Minn. State Board of Health.) from sewers, privies and cess pools. Underground contamina- tion may occur in clayey or gravely soils or in limestone regions, owing to the fissured or open character of the sub-soil. Shallow wells are frequently contaminated. 10. Emergency Protection in the Home. — The various do- mestic filters are of little value, as in order to give satisfactory results they must be cleaned frequently, at least daily, and it 10 146 PRACTICAL PREVENTIVE MEDICINE is rare for them to receive this care. They are apt to give a false sense of security. Boiling drinking water from 15 to 20 minutes is one of the best emergency safeguards that can be employed. Another method of equal value is the employment of bleach or chlori- WATER BEARING^ SAND OR GRAVEL Pig. 45. — Showing how a well can be protected against pollution. (Minn. State Board of Health.) nated lime. A stock solution of bleach is made by adding one teaspoonful of fresh chlorinated lime to a pint of water. • This is added to the drinking water in the proportion of one teaspoonful to ten gallons, or nine drops to one quart, and allowed to act for 15 to 30 minutes before the water is consumed. REFERENCES Race: Chlorination of Water. Stein: Water Purification Plants and Their Operation. WATER PURIFICATION 147 e_^ g ^rp$j:> |; .-^5? Pig. 46. — Showing how a spring can be protected against pollution. (Minn. State Board of Health.) 148 PRACTICAL PREVENTIVE MEDICINE Johnson: The Purification of Public Water Supplies. Water Supply Paper No. 315, U. S. Geological Survey. Freeman: Good Water for Farm Homes. Public Health Bulletin Xo. 70 U. S. Public Health Service. Farm Water Supplies. Bulletin Minnesota State Board of Health. Rosen atj: Preventive Medicine and Hygiene. 3rd Ed., pp. 878-911. Fig. 47. — Showing a properly constructed cistern located outside the house. {Minn. State Board of Health.) The Chemical Disinfection of Water. Reprint 225, Public Health Reports. Hypochlorite Treatment of Water Supplies. Reprint 261, Public Health Reports. Water Supply, Plumbing and Sewage Disposal for Country Homes. Bulle- tin 57, U. S. Department of Agriculture. Whipple: The Microscopy of Drinking Water. CHAPTER XVII PRODUCTION AND INSPECTION OF MILK i. Of all substances consumed as food the position of milk is unique. And of course in the northern temperate latitudes when we speak of milk one naturally understands that cows milk is understood. It owes its unique position to the following circumstances as pointed out by Rosenau: (i) It is the only standard article of diet obtained from animal sources that is ordinarily consumed in its raw state; i.e., it is not ordinarily heated in some cooking process prior to ^consumption. (2) Its peculiar composition renders it highly suitable as a medium for a wide variety of micro-organisms, both pathogenic and non-pathogenic. (3) The foregoing characteristics subject milk to rapid changes as a result of the activity of the micro-organisms, some of which may produce decompositions that render the milk unfit or even dangerous as food. As a consequence of these decompositions the original character of the milk may be largely lost or markedly altered. (4) The conditions of the production and the activity of micro-organisms make milk the most difficult of all animal foods to obtain, to handle, to transport and to deliver in a clean, fresh and satisfactory manner. These peculiarities serve to indicate the important relation- ship which milk possesses to both health and disease. Thus: (1) As a result of the favorable environment it creates for micro-organisms, it may serve as an important route for the dissemination of several species of infective agents; (2) Devised as it is by nature as the first food for the calf, it serves nearly equally as well as food for the young of the human species as well as for human adults, due to the proportion in which the different food elements are present. But on the other hand, when its composition is altered by microbial activity arising from improper care, it may become a dangerous instead of a safe food; (3) In addition to possessing all the different food elements in its composition, the elements are present in proper relative proportions, so that milk may be said to be the only 149 150 PRACTICAL PREVENTIVE MEDICINE properly balanced food. Furthermore all the different sub- stances present are readily digestible. If one tends to tire of a milk diet, the monotony may be relieved by some of the numerous modifications which the cook or housewife may devise. 2. Sophistication of Milk. — Unscrupulous dairymen the world over make a more or less frequent practice of altering the milk they retail, either by abstracting the more valuable con- stituents, such as the butter fat, or by adding diluents or en- deavoring to conceal changes of decomposition, or to prevent decomposition by improper methods. Under these headings come the practices of skimming, watering, adding of skimmed milk, thickening, coloring and the addition of alkalies or of chemical preservatives. These practices are unjustifiable and fraudulent, but since the health of the consumer is as a general rule unaffected, though his pocket book is depleted by fraud, we must regard this question as of economic importance rather than of sanitary importance. The only situation where the health of individuals might suffer as a consequence is in situations where milk of a certain composition is desired, as for example, for the feeding of tuberculous patients or of infants, with whom it would consti- tute the principal article of the diet. 3. Source of Micro-organisms in Milk. — The hygienic im» portance of milk is closely related to its microbial content, not that the myriads of micro-organisms which thrive in milk are in themselves necessarily harmful, but rather the extent of their abundance gives important information relative to the age of the milk, the degree of care exercised in its production and handling, and the conditions under which it has been stored. It must be borne in mind that an exact or even a fairly close approximate determination of the number of bacteria per unit volume of milk cannot be secured, and that the best re- sults are only in reality approximations. Furthermore the enumerations secured vary with the technic employed. An exposition of these phases of bacteriologic procedure would be too extensive for presentation here, so reference must be made to other sources of information. Since the questions of production, handling, storage and age, closely affect the microbial content of milk, it is necessary to consider their influences. (1) Production and Handling. — The amount of fresh milk consumed daily in this country is enormous. Practically all PRODUCTION AND INSPECTION OF MILK 151 the milk of this supply is furnished by small producers, the majority of whom at present have no special knowledge of the conditions necessary for the production of a hygienic milk, or the facilities to apply such knowledge. The milk supply of the large centers of population is secured from the small pro- ducers within a radius of from 100 to 200 miles and, owing to transportation difficulties, may be thirty six hours old when it reaches the consumer. On the other hand with the smaller cities and towns the radius of production is narrower and the consumer seldom gets milk 24 hours of age and usually less. Fig. 48. — Dirty flanks. A common condition in winter. Flanks become caked with manure, which there is often no thought of removing. This is the source of the dirt found in milk in winter time. (Webster, Bull. No. 56, Hygienic Laboratory.) The principal sources from which micro-organisms gain introduction are the following: 1. The udder and teats of the cow, as well as their flanks and bellies (Fig. 48). 2. The hands of the milker. 3. Dirt and dust of the stables (Figs. 50, 51). 4. Cow manure (Fig. 48). 5. Milking utensils. Of these the first, fourth and fifth are probably of greatest *5 2 PRACTICAL PREVENTIVE MEDICINE importance. In general it may be said that the presence of micro-organisms is closely associated with the introduction of dirt, particularly cow manure, which commonly gains introduc- tion from the teats, udder and flanks of the cow by dropping into the milking pail (Fig. 49). It is therefore apparent that a milking pail with a small top will prove of material assistance in reducing the amount of dirt that gains entrance (Fig. 59). In addition the thorough brushing of the cows with brush and curry comb (Fig. 52) followed by a wiping with a damp cloth, Fig. 49. — Sediment disks showing from o.oi to 0.5 gram of fresh manure removed from different bottles of milk. (Bull- 642, U. S. Dept. of Agriculture.) largely eliminates gross dirt from the milk pail. The character of the milk pails and utensils is of importance from another standpoint. If their interior is rusty or their seams rough, their cleaning is made difficult. Milk remains in the recesses in which bacteria multiply and which serve as cultures to seed the fresh milk when the utensils are again in use Hence in addition to possessing small tops, the milk pail should have a smooth interior and be subjected to sterilization after clean- sing. For this purpose streaming steam is very effective. (Fig 57). PRODUCTION AND INSPECTION OF MILK *53 The temperature at which the milk is tored between the in- terval of its production and its consumption is of great impor- tance. If kept at air temperature, bacterial multiplication will be rapid and the milk will soon spoil. The rapid cooling (Fig. 55) of the milk after its drawing and its maintenance at a temperature of io°C. (5o°F.) or lower will largely inhibit bacterial multiplication and hence prevent decomposition. Practically sterile milk in commercial quantities cannot be produced, but on the other hand, care in the production and handling of milk will keep the count very low. : Pig. 50. — Stable yards of this type are all too common. The cows are com- pelled to wade knee deep in manure in order to get into the stable Much of the filth on legs and tail from this source gets into the milk. (Bull. 56. Hygienic Laboratory.) 4. Classification of Milk. — From a hygienic standpoint we may consider either of two classifications of milk, first: (a) Raw milk, and (b) Pasteurized milk. Raw milk includes all milk that has not been heated to a temperature sufficient to destroy most bacteria, and which at the same time will not alter the nutritional properties of the milk. Hygienically, raw milk may be of any grade of the second classification. Potentially it is dangerous, since with 1 54 PRACTICAL PREVENTIVE MEDICINE the greatest of care it is impossible to prevent the introduction of infective agents into some lots. Pasteurization is a process of sterilizing or partially steri- lizing organic solutions without altering their chemical proper- ties, devised by Pasteur and first applied to beer and wines (Fig. 58). As applied to milk or cream three methods are in use. They are the following: (a) The flash method which from a hygienic standpoint is the poorest. It is used chiefly in those dairies run as adjuncts FlG. 51. — A dirty stable interior. (Bull. 56, Hygienic Laboratory.) to creameries, where the milk or cream is heated to destroy undesirable lactic fermentation. These lactic organisms are destroyed at temperatures lower than the pathogenic organisms likely to be present, hence the latter are not affected. The milk is momentarily heated but the temperature is not main- tained. (b) The holding process: The milk is heated in large vats and the temperature maintained for some time (Fig. 59). The temperature used is sufficient to kill pathogenic organisms. At the completion of the process the hot milk is cooled by running PRODUCTION AND INSPECTION OF MILK 155 over cooling coils and then bottled (Fig. 56). The process will efficiently destroy infective agents present, but the milk may be subsequently contaminated. (c) The in-bottle method, which is a modification of the holding process. The milk is run into clean bottles, the bottles capped with crown seals and submerged in vats of water which are heated to the desired temperature and this temperature maintained, or they are placed in closed chambers and sprayed with hot water. Various commercial modifications of the pro- FiG. 52. — Cleaning cows preparatory to milking. A simple operation re- quiring no other outlay than a little time. (Bull. 56, Hygienic Laboratory). cedure are in vogue (Figs. 60, 61). After heating the bottles are cooled and chilled. This method possesses the advantage that subsequent contamination is prevented. The most satisfactory pasteurization from a hygienic stand- point is achieved by holding the milk from 35 to 40 minutes at a temperature of 65 degrees C. (Fig. 58). Pasteurization does not alter the digestibility of the milk; though some may observe a difference in its palatability. The heating alters the vis- cosity of the butter-fat, so that a distinct cream line is not i56 PRACTICAL PREVENTIVE MEDICINE formed. Oxidases and vitamines are destroyed, so that pas- teurized milk used for infant feeding should be supplemented Pig. 53. — A clean light, airy interior. Milkers at work are dressed in clean white suits and caps. Cows are clean. An ideal place. (Bull. 56, Hygienic Laboratory). Pig. 54. — Types of milk pails. Narrow-top pails are best. (Bull. 56. Hygi- enic Laboratory). with orange juice to supply vitamines, otherwise some children may develop infantile scurvy. Pasteurized milk must be PRODUCTION AND INSPECTION OP MILK 157 cooled and carefully kept cool, otherwise it is apt to putrify instead of souring, due to the destruction of the lactic ferments, while the spore forming proteolytic bacteria survive the heating. To secure the maximum protection, all pasteurizing vats should be equipped with recording thermometers, and the process should be carried out under official supervision. 2. By another classification milk may be divided into three grades : (a) Certified milk. Pig. 54a. — A good type of inexpensive milk house. A milk house, separate from the dwelling and stable, is indispensable. Here the milk should be brought for cooling and bottling, and here the milk utensils should be cleaned and steri- lized. (Bull. 56, Hygienic Laboratory.) (b) Inspected milk. (c) Market milk. The use of the term certified, as applied to milk, is limited to milk produced in accordance with the requirements of the American Association of Medical Milk Commissions. For its production, the dairyman enters into a contract with the association, agreeing to the following conditions, in return for which his milk is certified. (a) The producing dairies shall be periodically inspected. (b) Frequent analysis of the milk shall be made. 158 PRACTICAL PREVENTIVE MEDICINE (c) Pure water shall be supplied for dairy use. (d) The dairy herd shall be free from tuberculosis as demon- strated by frequent inspections and tuberculin tests. In addi- tion all cows shall be free from other diseases liable to cause deterioration of milk. (e) The stables must be kept clean and be properly ventilated and lighted. (/) The cows must be properly fed and cared for. Pig. 55. — A very neat, inexpensive, small, bottling room. Note at the right the conical cooler, over which the warm milk is allowed to flow. (Bull. 56, Hygienic Laboratory.) (g) All milk handlers must be free from communicable dis- eases. They must observe scrupulous cleanliness in their work (Fig. 53). Qi) All care must be used in milking, the milk must be promptly cooled, placed in sterile bottles and stored at 50 de- grees F. or lower until delivered (Fig. 59). (i) A bacterial count not in excess of 10,000 per c.c. is per- mitted and the milk must not be over 24 hours old when delivered. Certified milk represents the highest grade of milk obtainable. Its careful production makes it well adapted to infant feeding. PRODUCTION AND INSPECTION OF MILK 159 Fig. 56. — Bottling room in a high-class city dairy. Milk is cooled by flowing over the corrugated cooler in the center of the illustration, after which it flows into the tank of the bottling machine below. (Bull. 56, Hygienic Laboratory.) ■■■H Fig. 57. — Loew hydro-pressure bottle washer. Installed in Meyer Sanitary Milk Co., Kansas City, Kansas. A machine for the washing and wrinsing of milk bottles. (Loew Mfg. Co., Cleveland, O.) i6o PRACTICAL PREVENTIVE MEDICINE The term inspected milk is applied to a very good grade of raw milk, however not as reliable as the certified grade. It is applied to clean, fresh milk from healthy cows which are tuber- culin tested and examined by a veterinarian. The cows are fed, watered, housed and milked under good conditions, but not necessarily equal to those required for certified milk. ao' •30' Time (Mmutesj. +0' ■50', Dr. CC.Nort/, Fig. 58. — Showing the time and temperature necessary for the destruction of infective agents in milk, with the effect of heat on the constituents of milk. (Dr. C. E. North, N. Y. City.) Scrupulous cleanliness must be used in milking and care taken to prevent persons having communicable disease coming in con- tact with the milk. It should be placed in sterile bottles and stored at 50 degrees F. A bacterial count of not over 100,000 bacteria per c.c. is permissible. The term market milk is applied to all milk not certified or inspected in accordance with the above definitions, and to all PRODUCTION AND INSPECTION OF MILK 161 milk of unknown origin. Common sense indicates the neces- sity for the pasteurization of all milk of this grade. 5. Dairy Inspection. — ImprovemeDt in the hygienic quality of milk can best be accomplished by supervision of the condi- tions under which milk is produced and handled. Results are accomplished along two lines (1) by the enforcement of regula- tions designed to secure proper conditions and methods, and Fig. 59. — A vat pasteurizer suitable for the pasteurization of milk by the holding process. (Miller Pasteurizing Machine Co., Canton, O.) (2) the education of dairymen along the lines of hygienic milk production. There can be no doubt that markedly bene- ficial results follow the introduction of efficient systems of in- spection by tactful inspectors. On the other hand, inspection will not cure all of the evils or absolutely safeguard the milk supply. Inspection requires that all sources of supply be examined, hence in order that they may be known to the authorities a system of liscensure is necessary. Inspections are 11 162 PRACTICAL PREVENTIVE MEDICINE of the greatest value when a fixed routine is followed in making the inspections. To this end score cards are of great value. ; ooung PAST€URtZ!NG "E-HEATlNa Pig. 60. — A large type of pasteurizing machine, for in-bottle pasteurizing. Capacity 5000 pint bottles per hour. (Barry-Wehrniller Machinery Co., St. Louis, Mo.) Fig. 61. — Loew in-the-bottle pasteurizer. Installed by Meyer Sanitary Milk Co., Kansas City, Kansas. Another type of in-bottle pasteurizer. The milk is heated by jets of hot-water. {Loew Mfg. Co., Cleveland, 0.) Score cards are constructed on a percentage basis, different values being assigned to different phases of the subject; equip- PRODUCTION AND INSPECTION OF MILK 163 UNITED STATES DEPARTMENT OF AGRICULTURE, BUREAU OF ANIMAL INDUSTRY, DAIRY DIVISION. SANITARY INSPECTION OF DAIRY FARMS. SCORE CARD. Indorsed by the Official Dairy Instructors' Association. Owner or lessee of farm ■_ , P. O. address State Total number of cows Number milking , Gallons of milk produced daily Product is sold by producer in families, hotels, restaurants, stores, to — dealer. For milk supply of. , Permit No ..— Date of inspection ...., 191 Remarks: _ _ „ Inspector^ D. ». 316.— 5-S-15— 5,000. 8—1763 Pig. 62. 164 PRACTICAL PREVENTIVE MEDICINE EQUIPMENT cows. Health. Apparently in good hoalth 1 If tested with tuberculin within a year and no tuberculosis is found, or if tested within six . months and all reacting ani- mals removed 5 (If tested within a year and react- ing animals are found and removed, 3) Food (clean and wholesome) Water (clean and fresh) ........ BTABLIS. Location of stable.. .............. Well drained i 1 Free from contaminating sur- roundings .X. Construction of stable Tight, sound floor and proper gutter .. 2 Smooth, tighc walls and ceiling. 1 Proper stall, tie, and manger 1 Provision for light: Four sq. ft. of glass per cow 1. (Three sq. ft., 3, 2 sq. ft., 2; 1 sq. ft., I. Deduct for uneven diBtribu- tion.) Iledding ....... Ventilation . Provision for fresh air, control- lable flue system ^ 3 (Windows hinged at bottom, 1.5; sliding windows, 1; other openings, 0.5.) Cubic feet of space per cow, 600 ft 3 (Less than 600 ft., 2; less than 400 ft., 1; less than 300 ft., 0.) Provision for controlling tem- perature.........™.. ... 1 TJTENBIL8. Construction and condition of uten- sils . .: Water for cleaning (Clean, convenieut, and abundant.) 8mall-top milking pail Milk cooler .... Clean milking suits MILK BOOM OE MILK HOUSE. Location: Free from contaminating surroundings Construction of milk room Floor, walls, and ceiling 1 Light, ventilation, screens 1 [Separate rooms for washing utensils and handling milk facilities for steam (Hot water, 0.5.) Total SCORE. Perfect. Allowed. METHODS. Clean (Free from visible dirt, 6.) STABLES. Cleanliness of staWcs. . ... Floor ; ... -_ .2 Walls .' I 1 Ceiling and ledges ... 1 Mangers and partitions 1 Windows 1 Stable air at milking time ... Freedom from dust 3 Freedom from odors 2 Cleanliness of bedding Barnyard . Clean ... I Well drained I Eemoval of manure daily to 60 feet from stable- '. MILK BOOM 0B MILE HOUSE. Cleanliness of milk room. UTENSILS AND MILKINO. Care and cleanliness of utensils Thoroughly washed 2 Sterilized insteam'for 15 min- utes 3 (Placed over steam jet, or scalded with boiling water, 2.) Protected from contamination. 3 Cleanliness of milking , Clean, dry hands 3 Udders washed and wiped :_ 6 (Udders cleaned with moist cloth, 4; cleaned with dry cloth or brush a t least 15 minutes before milking, 1-) HANDLING THE MILE. Cleanliness of attendants in milk room Milk removed immediately from stable without pouring from pail.. Cooled immediately after milking each cow Cooled below 50° F (51° to 55°, 4; 56° to 00°, 2.) Stored below 60° F (51° to 55°, 2; 56° to 60°, 1.) Transportation below 50° F f51° to 55°, 1.5; 66° to 60°, 1.) (If delivered twice a day, allow perfect score :&I storage and trans- portation.) SCORE Perfect. Allowed. Equipment- + Methods , Final Score. Note 1. — If any exceptionally filthy conditijD is found, particularly dirty utensils, the total score may be fur- ther limited. Note 2. — If the water is exposed to dangerous contamination, or there is evidence of the presence of a dangerou3 disease in aDimals or attendants, the score shall be 0. 8 — 1763 Pig. 62. — (Continued.) PRODUCTION AND INSPECTION OF MILK 1 65 merit and methods (Fig. 62). If perfect, a 100 score would be allowed, but suitable deductions are made for the observed deficiencies. The method permits of the tairest comparison of different dairies and permits the dairyman to understand the deficiencies of his equipment and methods. Where the score cards are devised upon a proper basis, i.e., emphasize the im- portant factors in the production of a safe milk and ignore or minimize the trivial features, excellent results will follow. It is physically impossible, however, to secure a sufficient staff of inspectors to insure the freedom of a milk supply from infec- tion at all times. Inspection is of value in the investigation of supposed milk born outbreaks and doubtless prevents many, but it is not an absolute safeguard. 6. The Care of Milk in the Home. — Proper care of milk in the home is of fundamental importance when employed in infant feeding, though less so in the case of adults. Its im- portance will be brought out later. For the present we will only consider what constitutes proper care. In the main this con- sists in maintaining proper conditions of storage, so that the milk is kept chilled until it is entirely consumed. In the homes of the well-to-do, where refrigerators and a constant supply of ice are available, this is no problem. On the other hand in the homes of the poor where refrigerators are not available, a little ingenuity, together with a regular supply of ice will meet all requirements. A very simple home made milk refrigerator is described in Public Health Bulletin No. 102 of the Public Health Service. It may also be advisable or necessary to pasteurize milk in the home, either as a routine or as an emergency procedure. Of course doubtful milk can be rendered safe by boiling, though few people find the taste of boiled milk palatable. Home pasteurization should be practised where cows milk is required for infant feeding and where the only milk available is of the inspected or market grades. Since the principles of pasteuriza- tion have already been explained it is not necessary to describe their adaption to this purpose, since ingenuity can readily adapt the process to local home facilities. (See circ. 197 Bureau Animal Industry, U. S. Dept of Agriculture). REFERENCES A Home Made Milk Refrigerator. Public Health Bull. 102, U. S. P. H. S. The Four Essential Factors in the production of Milk of Low Bacterial Count. Bull. 642, U. S. Dept. of Agriculture. l66 PRACTICAL PREVENTIVE MEDICINE Directions of the -Home Pasteurization of Milk. Circ. 197 for Bureau Animal Industry. U. S. Dept. Agriculture. A Simple Steam Sterilizer for Farm and Dairy Use. Farmers Bull. 748. U. S. Dept. Agriculture. Dirt Sediment Testing, a factor in obtaining clean milk. Reprint Series No. 15, Health Department. New York City. The Modern Milk Pail. Bull. 326, New York Agr. Expt. Sta., Geneva, N. Y. A Guide for Formulating a Milk Ordinance. Bull. 585, U. S. Dept. Agr. Production and Inspection of Milk. Spec. Bull. Hawaii Agr. Expt. Sta. Milk and its Relation to the Public Health. Bull. 56, Hyg. Lab., U. S. P H. S. Medical Milk Commisions and Certified Milk., Bull. 104, Bureau of Animal Industry, U. S. Dept. of Agriculture. Score Card System of Dairy Inspection. Circ. 199, Bur. An. Ind. U. S. De- partment of Agrictulture. Pasteurization of Milk in Bottles and Bottling Hot Milk Pasteurized in Bulk. Bull. 240, U. S. Dept. of Agriculture. The Thermal Death Points of Pathogenic Micro-organisms in Milk. Bull. 42, Hygienic Lab. U. S. P. H. S. Pasteurization of Milk. Circ. 184, Bur. An. Ind., U. S. Dept. Agr. Standard Methods for the Bacteriological Analysis of Milk. Am. Public Health Ass'n. History, Development and Statistics of Milk Charities in the United States. Reprint 50, Public Health Reports. CHAPTER XVIII MILK AS A ROUTE OF INFECTION 1. Milk as a Medium for Bacteria. — In this connection it is necessary to call attention to a phenomenon observed in milk which is commonly referred to as the "germicidal" property. In the first few hours after milk is withdrawn from the cow there is a transitory reduction in the number of colonies which develope on plates poured from unit volumes of milk, as com- pared with the number originally present. In a few hours the numbers show no furtner reduction, commence to in- crease and soon greatly exceed those originally present. This phenomenon is not apparent in milk which has been heated to 50 degrees C. . Several explanations have been advanced. (a) Some consider this phenomenon as a manifestation of a true germicidal property in milk and that the temporary diminu- tion is due to a partial destruction of the bacteria originally introduced. (b) Or it may be due to an inhibition of those species which find milk an unfavorable environment for development. (c) Others consider the phenomenon is due to the action of agglutination, i.e., the reduction in colonies is due to the clump- ing of bacteria and that their numbers are not actually reduced. This view is strengthened by the influence of heating as already noted. 2. Sources of Pathogenic Organisms which may be En- countered in Milk.- — First let us consider organisms derived from the producing animals: (a) Cows. 1. The mammary gland. Mycobacterium tuberculosis. Virus of foot and mouth disease. Bacillus anthracis. Virus of cow pox. Streptococci. 2. From fecal contamination. Mycobacterium tuberculosis. Bacterium enteritidis 167 1 68 PRACTICAL PREVENTIVE MEDICINE (b) Goats, i. The mammary gland. Bacterium melitensis. (Malta fever). Equally important are infective agents derived from human sources, thus: i. Fecal and urinary discharges. Bacterium typhosus. Various non-specific organisms producing diarrhea. 2. Nasopharyngeal secretions. Mycobacterium diphtheria. Virus of scarlet fever. Streptococcus hcemolyticus. (Septic sore throat). 3. Development of Pathogenic Bacteria in Milk. — All of the rapidly growing pathogenic bacteria find milk a very favorable medium, consequently their numbers will increase. Thus individuals consuming contaminated milk will ingest large numbers of the organisms, in other words, the dosage of infection will be great. The extent to which multiplication takes place is. modified by a number of factors among which may be mentioned the following: Germicidal property, tempera- ture of storage, age of the milk and the time at which the in- fective agents gain introduction. Of these temperature is one of the most important. The nearer the temperature of storage approaches body heat the greater will be the development of pathogenic organisms. The incidence of milk-borne disease in a given population is greatest among those who use milk as a beverage. A lighter incidence will be found among those who only employ milk on cereals, or as a diluent in tea, coffee or cocoa. Since women and children are usually the heaviest milk drinkers, the heaviest evidence of milk-borne disease is found in these age and sex groups. As we have seen, bacterial multiplication in milk is directly proportionate to the external temperature, conse- quently the dosage of infection in a given sample of infected milk will be greater in warm weather. As a rule milk-borne epidemics occur during the warmer seasons of the year, or follow- ing periods of warm weather in winter. The large dosage of infective agents received reduces the incubation period to its lower limits, but peculiarly, in the case of typhoid at least, the disease when milk borne is commonly milder than usual. In the care of typhoid and diphtheria transmission by milk it will be found that the contamination of the milk with these organ- MILK AS A ROUTE OF INFECTION 1 69 isms has been intermittent, frequently only a single lot being infected. Investigation will reveal the dairy or distributing agency responsible and the distribution of the cases will be found to coincide with the distribution of that supply. The possibilities in the contamination of milk and the range of its distribution are indicated in Fig. 64. 4. Bovine Tuberculosis in Man. — In the past widely diver- gent views have been entertained, from the belief that the bovine strain never affected man to the opposite view, that all human infection was derived from bovine sources. Such widely divergent views naturally stimulated research and as a consequence it is now possible to say with some degree of finality that the bovine tubercle bacillus is responsible for from 10 to 15 per cent, of all human tuberculosis, the clinical types produced being chiefly cervical adenitis, abdominal tuberculosis and generalized tuberculosis of alimentary origin. It is exceed- ingly rare in pulmonary tuberculosis, which is practically due only to the human strain of the tubercle bacillus. Infection is usually found in children under sixteen years of age, while susceptibility is greatest during the first five years of life. In New York City 7 per cent, of the deaths among those of less than five years of age are due to bovine tuberculosis. Infection is contracted through the consumption of contami- nated milk. When we consider the wide prevalence of the disease in cattle, as indicated by the following table and the small proportion of human infection, one must conclude that human infection is not very easy. The bovine tubercle bacillus has been found in the following proportions in the milk supply of different cities: New York City 16 per cent, of milk specimens examined. Washington City 2.7-6.7 per cent, of milk specimens examined. Chicago 7.9 per cent, of milk specimens examined. Manchester, England 8.9 per cent, of milk specimens examined. Tuberculosis is widespread among the dairy herds of the United States, though by constant effort, reduction is being gradually accomplished. A few years ago it was found that 302 of 421 dairy herds examined in the state of New York were infected. It has been authoritatively estimated that 30 per cent, of all dairy herds in the U. S. are infected. 170 PRACTICAL PREVENTIVE MEDICINE The presence of tubercle bacilli in milk usually arises as a result of milk contamination with bovine feces. Mammary- tuberculosis is very rare in cattle, only from 1 to 10 ten cent, of infected cattle having a tuberculous mastitis. On the other hand, pulmonary involvement is most common. The sputum instead of being expectorated is swallowed and the organisms pass out of the body with the feces. Since the disease is chronic and the infection commonly widespread in invaded herds, it is easy to understand that the contamination of the milk from an infected dairy will probably be continuous. On the other hand, the tubercle bacillus is very slow growing, so that in the interval between production and consumption of the milk no appreciable increase in the number of organisms will take place. Pasteurization of milk at a temperature of at least 6o°C. is the only safeguard against milk-borne tuberculosis. Further- more pasteurization should be in closed vessels to avoid the formation of the scum upon the surface of the milk which serves to insulate some of the organisms from the heat. The tuberculin testing of dairy cattle and the slaughtering of those found to react is a very satisfactory means of eradicat- ing the disease and has been successfully practiced for some time. This method, however, gives rise to serious losses in the case of blooded stock. To overcome this disadvantage the Bang system was originated. Reacting cows without open, lesions are not killed, but are permitted to be bred. Following calving the calves are immediately separated from their mothers and never permitted to suckle. The cows are milked and the milk pasteurized before being fed to the calves. Of course the reacting cows used for breeding are separated from all other healthy cattle. The success of this method lies in the fact that intra-uterine infection is so rare as to be a negligible factor in the dissemination of the disease. As a consequence, the desir- able qualities of highly bred cattle may be perpetuated and the losses are very much diminished, while healthy uninfected progeny are secured, and in the course of a few years a farm is clear of tuberculosis. 5. Milk-borne Typhoid Fever. — Since milk-borne typhoid fever was first recognized in 1857, over three hundred similar outbreaks have been reported in the literature and this must represent a minor fraction of the total. Milk-borne typhoid is urban rather than rural in character and is probably responsible for a considerable proportion of MILK AS A ROUTE OF INFECTION 171 endemic typhoid, represented chiefly as small epidemics. Ogan estimates that 39 per cent, of all typhoid fever in New York City is milk-borne. In Washington City the minimum number of milk cases represent from 9 per cent, to n per cent, of all typhoid, these cases occurring chiefly in small epidemics. An interesting bit of data in this connection is the following observation from Washington. TABLE VIII Year Pasteurization Cases on milk routes per ioo ,000 gallons Dealer 3 Dealer 4 Dealer 8 1906 none 16.6 52.5** 36.6 1907 none 7-i 21.6 17. 1 1908 yes 5-8 10. 1 18.8 * 1909 yes 1.4 7.0 6.9 ** A pronounced milk outbreak. * Not pasteurized until 1909. These figures clearly indicate that milk is a considerable factor in endemic typhoid, and demonstrates the protective value of pasteurization. In considering the introduction of the typhoid bacilli into the milk let us separately consider the dairy and the retail end. Infection of the milk at the dairy or producing farm has been observed to have resulted from the following practices or cir- cumstances in different epidemics (Fig. 64) : (a) Unrecognized cases serving as milkers or handlers. (b) The nurse of a typhoid patient serving as a milker or milk handler (Fig. 63). (c) Washing milk utensils in contaminated water. (d) Washing milk, utensils with the same dish cloths used for dishes of a typhoid case. (e) Adulteration of milk with infected water. From the standpoint of the distribution of a milk supply, the following circumstances have given rise to epidemics: (a) Unrecognized cases or carriers delivering milk or working in milk depots. (b) Use of bottles from premises on which typhoid cases existed without their previous sterilization. The development of the typhoid bacillus in milk is rapid as 172 PRACTICAL PREVENTIVE MEDICINE A LOCALIZED EPIDEMIC OP TYPHOID PEiVER DOE: TO AN INFECTED MILK. SUPPLY t Ae, RS.6O1 T 33 C/\5^5 OF TYPrtOlD feVej? devel- oped Anor\e RE.5IDEMT^ OF WEST pOll- tV/J DORlMG AAOMTrt OF OCTOBER. 1908 Ul I UUUU UUUL nan OODDl OODGOLU DDDDDDt OQOOOOt BDa DDDC rEDDJbfflOaQDDDlDt IDlilDIDDpDDaDfflt nffnrinnn ONiy I ME:W CA.5E OP TYPrtOID Wa.5 RE- PORTED IN TrilS DI5TRICT IN SO\/ej^BF,F,1908, Trif. INFECTED fVLK 50PPLV AA,VlN& BEE.H" 5T0PPE& OCT. 13,1908 UUUUUUUL D'QffiM OOOOO DDODD OOOO'O OOOOO OflOOO DTJUOELD D,D DiDO DIDlDI nnn DEPARTMENT OF HEALTH . CHICAGO. EDUCATIONAL £ERIE5-No15 Fig. 63. MILK AS A ROUTE OF INFECTION 173 the temperature rises above ten degrees C. As a consequence most milk outbreaks occur during the summer months or during warm periods in winter. The outbreaks are explosive in char- acter and affect milk drinkers most heavily, particularly women XI > D C line z z o z X) > o c 03 7 2z o)£ nc ?£ z z INFECTED WATER INFECTED FLIES INFECTED MILK UTENSILS INFECTED EMPLOYEES INFECTED BOTTLES INFECTION IN CONSUMERS HOME [Qp-T-A II I — INFECTED EMPLOYEES 5JOR1 Fig. 64. — The distribution of infection by milk. and children. The introduction of the infective agent is inter- mittent and as a result several explosive crops of cases may be observed. 6. Other Milk-Borne Infections. — The distribution of scarlet fever, diphtheria or septic sore throat by milk does not essen- I y4 PRACTICAL PREVENTIVE MEDICINE tially differ from that of typhoid fever, although they are of rarer occurrence. 7. Other Milk Products as Routes of Infection. — Dairy products, as well as fresh milk may serve to distribute infective agents. Thus the cream supply, ice cream, butter and butter milk must be borne in mind in the investigation of epidemics. REFERENCES Milk and its Relation to the Public Health. Bulletin 56, Hygienic Labra tory. U. S. Public Health Service, pp. 23-231; 455-525. Rosexatj: Preventive Medicine and Hygiene. 3rd, Ed. pp. 57i - 579- Relationship of Milk Supplies to Typhoid Fever. Reprint 380, Public- Health Reports. CHAPTER XIX OTHER FOOD STUFFS AS ROUTES OF INFECTION We will now give a brief consideration to the other food-stuffs, exclusive of water and milk. In this connection it is apparent that some, such as meat, may serve both as a source as well as a route of infection. I. Meat as a Vehicle of Infection. — The muscular tissue and certain viscera of cattle, sheep, swine, horses, dogs, and goats are largely consumed as food and constitute what we designate as meat. The animals slaughtered for this purpose may be diseased, in which event their meat may be unsuited for food for the following reasons: (a) Infective agents to which man is susceptible may be present. (b) The meat has an abnormal appearance and hence is repulsive. (c) As a result of the illness the food value of the meat is lowered. Furthermore careless methods of slaughtering may result in the contamination of the meat with micro-organisms from the intestinal tract, as a consequence of which decomposition takes place more rapidly. Danger from such causes may be eliminated by a careful ante mortem inspection of the animals and a similar inspection of the carcass following slaughter. The presence of diseased tissue does not necessarily justify the condemnation of the entire carcass. Condemnation should be based upon an accu- rate diagnosis of the diseased conditions detected, and the extent of its distribution. Many diseased caracasses can be safely used in part as food. In the United States but little progress in meat inspection has been made. The Federal system of meat inspection is only for meats designed for interstate shipment and export. Meats slaughtered for local consumption can only be supervised by local authorities and very little has been undertaken in this direction. (a) Diseases of animals which may be transmitted through meat: 175 176 PRACTICAL PREVENTIVE MEDICINE i. Meat Poisoning. — By this term is meant a group of infec- tions and intoxications due to the activity of several different organisms. The conditions are all highly acute and occur after a very brief incubation period, so that clinically they do not resemble typical infections. Bacterially we find the organisms concerned are B. enteritidis, B. proteus, B. paratyphosus B. and closely related forms, and also B. botulinus, whose action is due to highly potent soluble exotoxin. These outbreaks have usually been associated with the consumption of prepared meat foods (sausages, etc.) and pork has been the meat most com- monly involved. These organisms are present in the gastro- intestinal tract of the domestic animals and their presence in the meat is probably due to its contamination with the intes- tinal contents and feces after slaughter. The organisms of the enteritidis group are all killed by low degrees of heating (60 degrees for 30 min.), but they possess poisonous endotoxins which withstand a higher temperature. 2. Verminous Parasites. — Several cestodes and one nemotode are of considerable importance, the latter particularly. The beef tape worm, the pork tape worm and the fish tape worm all pass their larval stage in the flesh of the indicated animal and human infection with all is primarily derived from the consump- tion of parasitized meat. The pork tape worm possesses greater importance than the others, since an individual once infected can reinfect himself, as man can also serve as inter- mediate host. The most important parasite is the nematode worm, Trichinella spiralis, whose larval stage is commonly passed in swine. Human infection is derived from raw pork. It is undoubtedly the most common and the most important of all infections derived from meat. 3. Other Infections. — Tuberculosis, anthrax, rabies, glanders, tetanus and foot and mouth disease are all diseases of the food producing animals, transmissible to man, yet so far as we know, no cases are on record where human infection was contracted from the consumption of infected meat. Man is susceptible to all of these, but his infection is derived from different routes than meat. 3. Shell Fish as a Vehicle of Infection. — Oysters, clams, cockels or mussels are frequently secured from beds in bays, inlets, etc., that are contaminated by the sewage of large com- munities, or else floated in brackish water similarily contami- nated (Figs. 65, 66). Thus opportunities are afforded for the shell fish to become contaminated with infective agents de- OTHER FOOD STUFFS AS ROUTES OF INFECTION 177 rived from human excreta. A considerable number of typhoid epidemics have been ascertained to have been caused by the t.-*i*i%! t "%iA Fig. 65. — Two oyster floats anchored in the rear of oyster houses. Privy vaults are located in the rear of these buildings, refuse being dumped directly into the river. It is a crime punishable by $100 fine to float oysters in this river. An epidemic of typhoid occurred some years ago from oysters floated in this place. {Bull. 136, Bur. Chemistry.) Fig. 66. — A closer view of the upper oyster floats shown in Fig. 65. Note the pile of oysters in the float. Picture taken at low tide; about two hours later these same oysters were found in the adjoining oyster house ready for sale. Oysters drink best at the beginning of flood tide and are "plumpest" about one or two hours afterwards. The main sewer of the city empties under the bridge above. {Bull. 136, Bur. Chemistry.) consumption of sewage contaminated oysters and clams. These observations have chiefly been made in England. The typhoid 12 178 PRACTICAL PREVENTIVE MEDICINE bacillus will survive in oysters for as long as six weeks, and as changes of decomposition set in, will increase in numbers. 4. Cooked and Canned Foods. — For the most part hygienists have looked upon cooking as a process of distinct hygienic value, entirely apart from its influence upon the digestibility of food, for the application of heat will have a distinctly dis- infecting action. However it now appears that not all cooking operations can be considered sufficiently thorough to altogether eliminate danger in cooked foods. The greatest danger appears to exist where large lots of food are cooked at one time, for here the bulk of the material is so great that the interior is insufficiently heated and hence not sterilized. Furthermore bacterial spores can survive cook- ing or the canning process. Little positive epidemiological evidence is at present available concerning food as a route of infection. Baked Spaghetti: An extensive outbreak of typhoid has been observed in California in which infection was derived from the consumption of a large dish of baked spaghetti prepared by a typhoid carrier. Experimentally it was found that in baking such a large dish that the typhoid bacillus could survive even though the exterior was charred. Fried Fish: Several outbreaks of typhoid fever in London appeared to be due to the consumption of fried fish secured from sewage contaminated waters. Botulism: Recently considerable evidence has been brought forward from the Pacific coast to the effect that the spores of B. botulinus can survive the process or canning. Several out- breaks of botulism due to the consumption of home canned vegetables have been reported. Outside of this area botulism is practically unknown in this country. The European out- breaks have occurred in connection with the consumption of pork sausage. On the other hand, commercially canned foods have not until recently been implicated in botulinus intoxication. A few in- stances of cans of contaminated ripe olives which caused epidem- ics, have been noted. It would appear that commercially canned food from cans that are not obviously spoiled (swollen, leaky) are as safe as any foods available. 5. Fresh Vegetables. — A few outbreaks of typhoid have occured as the result of the consumption of raw fresh vegetables grown in gardens heavily manured with human excreta. In this OTHER FOOD STUFFS AS ROUTES OF INFECTION 1 79 connection celery, lettuce, radishes and watercress have been incriminated. REFERENCES Rosenau: Preventive Medicine and Hygiene. 3rd Ed., pp. 605-643. Chapin: Sources and Modes of Infection. Chap. VII, pp. 266. Shell Fish Contamination from Sewage Polluted Waters and from other Sources. Bull. 136, Bur. Chemistry. W. S. Dept. Agriculture. Vegetable as a possible factor in the dissemination of typhoid fever. Re- print 82, Public Health Reports. CHAPTER XX INSECTS AS VECTORS OF INFECTIVE AGENTS Two types of the insect transmission of infective agents are discernable, namely biological and mechanical. i . Biological Transmission. — In this group transmission of the infective agent is accomplished by the aid of some blood sucking arthropod in whose body certain definite stages of the infective agents' life cycle are passed. So far as known the infective agents transmitted by this means have no other means of transmission. Biological transmission of the parasites producing the follow- ing diseases is certain, namely; Malaria, Yellow Fever, Sleeping Sickness, Rocky Mountain Spotted Fever, Chagas' disease, Relapsing Fever, Typhus Fever, and Kala Azar. It is prob- ably the usual means of transmission of Filiariasis and Dengue. The parasites concerned in this method of transmission are quite diverse, though apparently all belong to the animal kingdom. Thus we have protozoa, filterable viruses and nematodes. The groups of arthropods concerned are also quite diverse, although they all have the common habit of sucking blood, as for example; mosquitoes, biting flies, biting bugs, ticks, and lice. These arthropods are either temporary or permanent ectoparasites of mammals, living a life more or less intimately connected with the mammalian species upon which they prey. The infective agents concerned undergo oniy an asexual multiplication in their vertebrate host, hence the vertebrate is known as the intermediate host. On the other hand, sexual development takes place in the arthropod which is known as the definitive host. The relation of the infective agents to the arthropod species concerned in their transmission is usually specific or nearly so. Where not specific we find that only closely allied species of arthropods are involved. Similarly we may find a high degree of specificity on the part of the infective agent and the vertebrate host, although in some in- stances several species of mammals may apparently serve equally well. The influence of temperature and rainfall is noticed in the 1 80 INSECTS AS VECTORS OF INFECTIVE AGENTS 151 distribution and prevalence of these diseases, due to the effect which these climatic factors exercise upon the breeding oppor- tunities of the insects and hence influence their abundance. Temperature also profoundly influences the development of the protozoan parasites within their insect hosts, for example the distribution of malaria is limited by the annual isotherm of 60 degrees F. due to the inability of the malarial parasites to develope in the mosquitoes at a lower temperature. Thus low temperature may even inhibit protozoan development or sterilize the insect altogether. On the other hand, with favor- able conditions of temperature it would appear that infection of the insect is usually permanent. With infective agents whose transmission is biological, a definite lapse of time must occur before an insect which has become infected can transmit the infective agents to the host upon which it feeds. This period of noninfectivity is known as the extrinsic period of incubation and represents the time necessary for the infective agent to complete its sexual cycle in the insect and reach the appropriate point of exit. The routes by which the mature infecting forms of the in- fective agents leave their arthropodal hosts varies with different species. In the case of trypanosomes present in Tse-tse flies, departure is by the food canal of the probosis; in the cases of the malarial parasites in the anophelines the departure is by the salivary ducts in the probosis; with the spirochetes of relapsing fever in either lice or bedbugs the departure may be either with the feces through the anus, or by liberation from the body cavity when the insect is crushed. In some few species hereditary infection of the insect host is known, thus for example the piroplasms of Texas Fever pass to the ovaries and young ticks are congenitally infected. The same also occurs in African Relapsing Fever. As already noted the infectivity of the definitive arthropodal host is influenced by : (1) external temperature, which controls the development of the parasite within the insect; (2) The digestive processes of the insect, which may unfavorably influence the parasites; and (3) the presence and number of mature sexual forms of 1 he parasites in the blood of the vertebrate upon which the insect has fed. Each feeding only removes a very small quantity of blood and unless the parasites are sufficiently numerous in the blood abstracted and both sexual forms are present, infection of the insect will not occur. All the chances are against the parasite. Thus we can understand that fre- 152 PRACTICAL PREVENTIVE MEDICINE quently only one or two per cent, of anopheline mosquitoes will show malarial parasites, yet under more favorable cir- cumstances where heavy gamete carriers are abundant, as many as 20 to 25 per cent, of mosquitoes will be infected. The ability of any insect transmitted infection to gain a foot- hold and maintain itself requires at least two conditions: (1) That the definitive insect host exist in a certain degree of abundance, and (2) That intermediate mammalian hosts harboring the transmitting stage of the- parasite be accessable to the insects. Thus the eradication of malaria can be accom- plished without absolutely exterminating all anophelines in an area, by reducing their numbers to such a point that very few if any anophelines will have an opportunity to bite a gamete carrier. 2. Mechanical Insect Transmission. — Transfer of infective agents by this means may either be through the assistance of biting or sucking insects. The diseases in which the mech- anism is more or less clearly understood are all due to bacterial infective agents. The relationship of the insect and parasite is not specific, that is the parasite can be transferred from man to man by other agencies and frequently those other agencies are of greater importance in the propagation of the different diseases than the insects. The presence of infective agents in or on the insect is more contaminative in character, the insect relationship does not play any essential part in the life cycle of the parasite and commonly we find that the insect can imme- diately transfer infection after having had an infective meal. In other words an extrinsic incubation period is not observed. Temperature and humidity exercise a similar influence upon the development of the insect vectors of this group, and their influence is thus exerted and manifested in the seasonal and climatic distribution of these diseases, or else influence the bacterium within or upon the nsect. The diseases whose infective agents may be transmitted by this means are plague, cholera, typhoid, and both bacillary and amoebic dysentery. Fleas are concerned in the transmission of plague, and flies, principally the house fly, in the transmission of the others. In the case of the former, the plague bacillus leaves the flea's body both by the probocis and the feces; in the case of the latter group, the flies' probocis, its excreta, regurgitated material and the exterior of its body surface may afford means of convey- ance. In the former instance the infective agents are directly reintroduced by the insect into a new host, in the latter trans- INSECTS AS VECTORS OF INFECTIVE AGENTS l8 3 mission is effected through the contamination of food by the insect. 3. The Activity of the House Fly. — The house fly (Musca domestica) (Fig. 67) is an ubiquitous insect with a world wide distribution, living in close association with man. Its ova are preferably deposited in manure piles, from these hatch the familiar maggots (Fig. 68), which burrow through the pile and feed on the decaying organic matter. In about a week in the summer these leave the manure and burrow in the soil Pig. 67. — The house fly. {Public Health Reports, Supplement 29.) where they pupate. In a few days the adult fly emerges. The entire life cycle may be completed under favorable circum- stances in from 10 to 14 days. The dangers arising from this insect are due to its promiscuous feeding habits and its intimate association with man. It will walk over and feed upon the fecal deposits in a privy, the refuse in a garbage can, the pas- tries in a bake shop and the food in the kitchen and pantry with equal impartiality and in turn, conveying infective agents secured from the excreta to food during its journey. There is absolutely no question but that in unsewered cities and towns 1 84 PRACTICAL PREVENTIVE MEDICINE or in rural areas where fly tight privies are not used, flies are a great menace and an actual source of danger. They are un- doubtedly a considerable factor in the autumnal increase in typhoid. A very marked reduction in the incidence of typhoid fever was secured in Jacksonville, Florida following systematic efforts at fly elimination through prevention of breeding, the extension of the sewer system and the substitution of fly proof provies for open closets. Prior to 1910 there were about 8,500 privies in Jacksonville, which accommodated about 40 per cent, of the population. They were distributed uniformly over the entire town. None were fly proof in the slightest. Fig. 68.- -Larvse, or maggots, of the house fly. About natural size (Newstead). {Farmer's Bull. 851.) The typhoid cases annually reached a maximum in the fly season, while water and milk could be eliminated as a cause. In 1910 there were 329 reported cases with 62 deaths. Late in 1 9 10 an ordinance was passed requiring the fly proofing of all privies, a requirement that was completely met before the season of 191 1. During 191 1 there were 158 reported cases and 40 deaths and in 191 2 87 cases with 16 deaths. Of the 191 1 cases 88 received infection outside of Jacksonville, i.e., were imported and of the 191 2 cases 48 were imported. Later years continued to show the same results. This recalls the experience with fly borne typhoid in the southern army camps INSECTS AS VECTORS OF INFECTIVE AGENTS 1 85 during the Spanish war, in which, however, the role of the flies was not recognized until serious losses occurred. Dysentery bacilli may survive in flies for as long as five days, and typhoid bacilli may similarily survive nearly seven days. This relates to the organisms in the flies intestinal tract, from which they are discharged in the excreta (fly specks) or by regurgitation, though on the external surface of the body their survival is brief. Difficulties with flies can best be overcome by the elimination of their breeding place, namely manure piles. These if open and exposed should not be permitted to represent over a weeks accumulation. Stables should have tight floors and be well cleaned. The removal of manure at weekly intervals will re- move the partially developed maggots therein and afford local relief, but however, merely transfer the difficulty to some other situation. Another, but more expensive method, involves the keeping of flies from manure by requiring its storage in fly tight bins or boxes. Another solution to this problem is afforded by the treatment of manure piles with substances which destroy the larvse. Substances must be used which are not too expen- sive. Borax may be used at the rate of 0.62 pounds of borax per 8 bushels of manure, but the treated manure may have an injurious effect on vegetation. Powdered hellebore, using one half pound to 10 gallons of water and applying this amount to each 8 bushels of manure is perhaps the most effective and prac- tical substances to use for this purpose. Trapping and other- wise catching the adult flies, particularly if practised at the beginning of the breeding season, is of distinct merit. Sticky fly paper and the swatter should be used in every home and eating house. Dwellings and eating houses should be screened, and food displayed at retail, particularly that eaten without further heating, should also be screened. Traps of different kinds are in vogue, some of which are de- signed to be placed near doors, where flies seek ingress, others over garbage cans or manure boxes, are all of value. Unless attention is paid to the breeding places however, traps are of slight service. Garbage accumulations should receive atten- tion similar to manure. The activity of flies as conveyers of infective agents from excreta gives opportunity to reiterate the importance of col- lecting human excreta in privies that are of fly tight construction. 4. Insecticides. — Various methods are available for the de- struction of insects within dwellings, buildings, vessels, and other enclosed spaces. Their destruction by gaseous poisons is the 1 86 PRACTICAL PREVENTIVE MEDICINE most satisfactory method, and is generally applied for the pur- pose of destroying either the types which have a closer parasi- tism, such as fleas, or bed bugs, or noxious types such as clothes moths, cockroaches, or vectors which may be present on the premises from which a case of plague, yellow fever, etc., has been removed and hence are potentially infected. For this purpose either sulphur dioxid or hydrocyanic acid gas are commonly employed. The employment of gaseous in- secticides demands that the quarters to be freed of insects be given the same preparation as that required for disinfection. When employed as an insecticide, it is not necessary that water vapor be employed with the burning sulphur, as anhydrous SO2 is effective. For this purpose two pounds of sulphur are re- quired for each 1000 cubic feet of space. Crushed sulphur sticks or flowers of sulphur should be employed. The required amount of sulphur should be placed in a conical pile in a very shallow cast iron pot, which is supported on bricks in a tub of water. A small depression is made in the summit of the pile in which is placed a ball of waste or cotton saturated with alcohol. When all other preparations are completed the alco- holic cotton is ignited and the operator immediately makes his escape. The quarters should remain closed for from 2 to 12 hours. The objectionable features of sulphur dioxid have been noted in the consideration of disinfectants. A more satisfactory insecticide is hydrocyanic acid gas. It however is exceedingly poisonous to all mammals and man and should only be employed by one who is thoroughly competent and who fully understands its dangers. The gas is liberated from either sodium or potassium cyanid by means of sulphuric acid. Per 1000 cubic feet of the followirg proportion of these are required: KCN 10 oz. H2SO4 15 oz. H 2 22 . 5 OZ. Place the required amounts of acid and water in a glazed earthen ware jar, observing the usual precautions in the mixing. Complete all other preparations and be ready to make a hurried exit. Have the cyanid wrapped in a paper and drop it in the jar and instantly leave the room. Keep the quarters closed at least one hour. If several rooms are to be treated some ar- rangement with slings should be devised for lowering the cyanid into the acid from the outside. Both cyanid and SO2 are also employed for the destruction INSECTS AS VECTORS OF INFECTIVE AGENTS 1 87 of rodents. In maritime quarantine the exhaust gas from gaso- line engines or the funnel gas from burning coal are also em- ployed, due to the large content of carbon monoxide present. For small rooms or infrequent treatment it is not practical. Another substance of great value for this purpose is carbon bisulphid, but whose wide employment is limited owing to its inflammable and explosive qualities. Carbon bisulphid volati- lizes rapidly and is fully as explosive as ether. The gas is heavier than air. It is best adapted to the treatment of clothes rather than rooms and is preferably employed in small air tight closets or chests. It should be allowed to volatilize in the pro- portion of one pound per ioo cubic feet. The container from which it evaporates should be placed at the top of the enclosed space. It should be allowed to act for 10 to 12 hours. Insect powders have some value, particularly those composed wholly or in part of dried pyrethrum flowers. These are burnt, or diffused through the air as a powder. The vapor or dust stupefies the insects so they fall to the floor and may be removed by sweeping. Pyrethrum is not injurious to man. The body louse, because of its intimate relationship to man, cannot be altogether controlled by fumigation unless the clothing of all infected individuals is fumigated at the same time. For the delousing of clothing and bedding, physical agents give better results than fumigants, although in emer- gency work circumstances will largely control ones' efforts. Streaming steam will kill both adult lice and nits in 20 minutes and dry heat for 20 to 30 minutes at 60 degrees C. will also destroy adults or nits. Simultaneous attention must be paid to lice on the person, particularly in the hair. The old standby of kerosene and vinegar is probably best for this purpose. REFERENCES Rosenau: Preventive Medicine and Hygiene. 3rd Ed., Chap. IV, pp. 201. Doane: Insects and Disease. Carbon bi-sulphide as an Insecticide. Farmer's Bull. 799, U. S. Department of Agriculture. Fleas and their Control. Farmer's Bull. 897, U. S. Dept. Agr. Fly traps and their operation. Farmer's Bull. 73r, U. S. Dept. Agr. The house fly. Farmer's Bull. 851, U. S. Department of Agr. The transmission of disease by flies. Supplement 29. Public Health Reports. Further experiments in the destruction of fly larvae in horse manure. Bull. 245, U. S. Dept. Agriculture. The stable fly. Farmer's Bull. 540, U. S. Dept. of Agr. Experimental studies of muscicides and other fly destroying agencies. Bull. 108, Hygienic Lab. U.S.P.H.S. Hydrocyanic acid gas against household insects. Farmer's Bull. 699 U. S. Dept. of Agriculture. CHAPTER XXI DISEASES TRANSMISSIBLE BY INSECTS MALARIA i. Infective Agents. — (a) Plasmodium vivax, causing simple tertian fever. (b) Plasmodium malaria causing quartan fever. (c) Plasmodium falciparum, causing malignant tertian or estivo-autumnal fever. 2. Source of Infection. — Human beings whose blood contains tne gametes or sexual forms of the parasites, either those having acute or chronic malaria, or merely carriers. 3. Portal of Exit. — Blood abstracted by anopheline mosquitoes. 4. Route of Transmission. — -Through the agency of anophe- line mosquitoes which have bitten persons whose blood contains gametes. The sexual cycle of the parasite requires about 12 days for completion in the mosquito, at the end of which period the infecting forms (sporozoites) have made their appearance in the salivary glands (extrinsic period of incubation). In the United States there are three species of anopheline mosquitoes which can serve as vectors namely Anopheles quadrimaculatus (maculipennis, syn.) (Fig. 69, 73), Anopheles punctipennis and Anopheles crucians. Their ova, (Fig. 70) are most com- monly deposited in open collections of water distant from dwellings, although they may be found in rain barrels, cisterns, etc., near homes. The adults are nocturnal in their habits. Only the females are blood suckers and hence only the females transmit malarial parasites. External temperatures below 15 to 16 degrees C. will inhibit the development of the parasite in the mosquito. Of the three species the quartan can develope at the lowest temperature, while the aestivo-autumnal requires the highest. Adult mosquitoes that successfully hibernate are rendered sterile. Infection is maintained by human gamete carriers. So far as is certainly known mosquitoes are not hereditarily infected. 5. Portal oj Entrance. — Sporozoites are liberated in the sub- cutaneous tissues or capillaries by the discharge of the salivary secretions of infected mosquitoes when biting. DISEASES TRANSMISSIBLE BY INSECTS 189 6. Incubation Period {Intrinsic). — The duration of this period is influenced by the external temperature, being shorter during Fig. 69. — Anopheles maculipennis. {Ludlow: Bull. 4. Surgeon General's Office. War Dep't.) Pig. 70. — Egg of anopheles, dorsal view. (After Nuttall and Shipley.) (Doane: Insects and Disease, Henry Holt and Co.) high temperatures. It is usually about two weeks with Plas- modium vivax. The length of time following the onset before 190 PRACTICAL PREVENTIVE MEDICINE gametes appear varies with the different species. Thus, in Tertian, from 8 to 20 days; Quartan, 11 days (for one observa- tion); Malignant tertian, from 10 to 35 days. ' Fig. 71. — Anopheles larvae, the one to the right feeding, the other just coming to the surface. (Doane: Insects and Disease, Henry Holt and Co.) Fig. 72. — Anopheles pupas resting at surface of water. Disease. Henry Holt and Co.) (Doane: Insects and Fig. 73.— Malarial mosquito (A. maculipennis) on the wall, showing the resting posture characteristic of Anophelines. (Doane: Insects and Diseases. Henry Holt and Co.) DISEASES TRANSMISSIBLE BY INSECTS 19I In temperate climates infection is maintained not by the survival of the infected mosquitoes through the winter, but by the reinfection of the mosquitoes from human gamete carriers in the spring. 7. Period oj Communic ability. — As long as gametes are present in the circulation. This may be indefinitely. 8. Methods of Control. The Injected Individual {Active Malaria). — [a) Diagnosis: Clinical manifestations, always con- firmed by detection of the parasites in the blood. (b) Isolation: Protection of the patient from mosquitoes until his blood is free from parasites, especially gametes, by the use of screens or bars. (c) Immunization: None. (d) Quarantine: None. (e) Concurrent Disinfection: None as such. Destroy by capture or swatting all mosquitoes in the sick room. (/) Terminal Disinfection: Same as before. General Measures. — (a) Search for gamete carriers by the exam- ination of blood smears. Intensively treat such persons with quinine until sterilized. For adults Bass recommends 10 grains of quinine sulphate every night before retiring, continued for 8 weeks This treatment will destroy the parasites in 90 per cent, of the carriers. The remaining 10 per cent, should receive 3, ten- grain doses a day for three or four days and later 10 grains a day for eight weeks. Infants and children should be dosed as follows: Under 1 year 0.5 grain . 1 year 1 .0 grain 2 years ' 2.0 grain 3 to 4 years 3.0 grain 5, 6 and 7 years 4.0 grain 8, 9 and 10 years 6.0 grain 1 1-14 years 8.0 grain 15 years 10. o grain (b) Prophylactic administration of quinine: The daily admin- istration of 3 grains of quinine will prevent infection from de- veloping. Where employed on a large scale provision must either be made for its distribution gratis or at a very low charge. (c) Destruction of mosquito breeding places, by: 1. Drainage (Figs. 76, 77). 2. Training of water courses, or by 3. Filling. 192 PRACTICAL PREVENTIVE MEDICINE Attention should be paid to all depressions both natural and artificial, and of either stagnant or running water within one half mile radius of the area where control operations are being prosecuted. The planting of eucalyptus trees in swampy wet areas that for one reason or another cannot be drained, has been recom- mended, but their value for this purpose is undetermined. They apparently accelerate the evaporation of the swamp water. (d) Destruction of Mosquito Larvae. Two methods may be used. Pig. 74. — Oilers at work in marsh. (Gorgas, " Sanitation in Panama," Appleton's.) i. The application of a thin iridescent film of oil to the sur- face of water areas it is not feasible to drain, at least after every rain. The oil is either sprayed from knapsack sprays, or fed by drip cans. The latter are only adapted to streams or ditches conveying running water. Crude oil is best (Figs. 74, 75). 3. Stocking swamps and pools with species of fish that are predatory upon mosquito larvae. The Public Health Service is introducing the employment of the top minnow, Gambusia affinis, for this purpose. 2. The application of solutions having a lethal action on the larvae, such as the "Larvacide" of Darling. This is prepared DISEASES TRANSMISSIBLE BY INSECTS [ 93 from crude carbolic acid of a sp. gr. not greater than 0.97 and containing not less than 30 per cent, tar acids. One hundred p IG _ 7,^ — Burning out ditch with oil spray. (Gorgas, "Sanitation in Panama, Appleton's.) Fig. 76. — Prolific source of anopheles, horse-lot drain, Crossett. (Derivaux, Taylor and Hess, P. H. Bull. 88, U. S. P. H. S.) and fifty gallons of the phenol are heated in a tank and to this 200 pounds of finely crushed and sifted rosin are added and also 30 pounds of caustic soda dissolved in 6 gallons of water. This 13 194 PRACTICAL PREVENTIVE MEDICINE is well mixed. For use a 1 15 dilution in water is made. This is sprayed on water accumulations until the water has a thin milky opalescence (about 1:5000). In applying either oil or larvacide especial attention must be given to the margins and weedy places in the streams and pools. Depending upon the degree of agitation and the amount of fresh water introduced by rain, etc., repeated application of these will have to be made at irregular intervals. (e) Destruction of Adult Mosquitoes: 1. Adult mosquitoes may be naturally destroyed by the encouragement of various natural predaceous enemies, such as bats, dragon flies, etc. These alone, however, will not suffice. Pig. 77. -Same as Pig. 76, after treatment. (Derivaux, Taylor and Hess. P. H. Bull. 88, U. S. P. H. S.) 2. Swatting or trapping of adult mosquitoes in dwellings: They prefer to hide in dark corners during the day, where patient search will soon result in their discovery. One may also fumigate by burning pyrethrum. (/") Exclusion of adult mosquitoes from dwellings. Screening is the best method of accomplishing this result. A fine mesh screen of at least 19 to 20 strands per inch should be employed. All external openings should be screened, in- cluding windows, doors, fireplaces, or chimneys, cracks, etc. If possible verandas or galleries should be screened, rather than to limit one's efforts to the windows and doors leading out upon them. Doors may be protected by screened vestibules if necessary. In the absence of screening bars should be pro- vided for all beds. DISEASES TRANSMISSIBLE BY INSECTS 195 Screening and the control of mosquito breeding on the living premises are remedies available to every householder. On the other hand, the elimination of areas of extensive breeding is an effort that requires concerted community action. The methods or combinations of methods required to meet local conditions will vary, and require the exercise of considerable judgment. The question of initial cost and maintenance costs will likely be factors that largely influence the permanency of the efforts. At Havana, Panama, lsmailia and a few other places, the importance of mosquito control to the authorities was such that expense was not considered in securing the desired result. On the other hand, the control of malaria in the southern United States is a problem that will only be solved by methods that are within the slender resources of the average rural community. The possibilities in this direction have been brilliantly demonstrated by the work of Dr. H. A. Taylor in a group of rural towns in south eastern Arkansas. In the four towns in which antimosquito measures were undertaken in 19 18, there was an average reduction in the incidence of malaria of 89 per cent. The operations included the cutting of new drain- age ditches where necessary, the recleaning and regrading of old streams and the oiling of all accumulations of water not possible to drain. This was accomplished at an average per capita cost of eighty eight cents. The work requires careful and intelligent supervision. YELLOW FEVER i. Injective Agent. — Probably the spirochete (Leptospira icteroides) reported by Noguchi. 2. Source oj Injection. — Typical and atypical cases of yellow fever, possibly only during the first three days of their illness. 3. Portal oj Exit. — Blood abstracted by Stegomyia jasciata (Aedes calopus) (Fig. 78). 4. Route oj Transmission. — So far as known only by the agency of one species of mosquito, Stegomyia jasciata, which has fed upon the blood of yellow fever patients. The unknown parasite undergoes an extrinsic incubation period in the mosquito of at least 12 days before the mosquito can transmit the virus. 5. Portal oj Entrance. — Through the puncture wounds in the skin made by mosquitoes, to the subcutaneous tissues. 6. Incubation Period. — (Intrinsic) from three to six days. 196 PEACTICAL PREVENTIVE MEDICINE 7. Period oj Communicability. — Probably only during the first three days of the illness. 8. Methods of Control. The Injected Individual. — (a) Di- agnosis: Clinical observations only. (b) Isolation: In a well screened room or ward which has been freed of mosquitoes. (c) Immunization: None. (d) Quarantine: Of contacts for six days. (e) Concurrent Disinfection: None. (/) Terminal Disinfection: Fumigate to get rid of mosquitoes. General Measures. — (a) Eradication of mosquitoes by meas- ures described under malaria. Since the habits of Stegomyia differ from those of anophelines, some difference in the water accumulations attacked must be noted. The Stegomyia is a species that lives closely in association with man, breeding largely Pig. 78. — The yellow-fever mosquito: Adult female, side view. Much en- larged. The silver and black markings give the insert a very striking appear- ance. Note the silver crescents on the thorax. (Howard: Farmer's Bull. 547.) in artificial accumulations of water close to dwellings, such as cisterns, barrels and cans (Fig. 79). It is diurnal in its first feeding and later nocturnal. It is never found in marshes or swamps, so that attention need not be given to these unless a simultaneous attack on malaria is also desired Epidemic Measures. — (a) Inspection service to detect un- reported cases. (b) Fumigation of houses in which cases have occurred, and also of the adjacent houses. (c) Removal of patients to screened isolation hospitals. DENGUE i. Infective Agent. — Unknown. 2. Source oj Injection. — So far as is known only typical and atypical human cases. DISEASES TRANSMISSIBLE BY INSECTS I97 3. Portal of Exit. — In the blood abstracted from patients. 4. Route of Transmission. — By agency of mosquitoes (Steg- omyia fasciata) which have fed upon dengue patients. The extrinsic incubation period is unknown. 5. Portal of Entrance. — Through puncture wounds made by mosquitoes in the skin, into the subcutaneous tissues. 6. Incubation Period. — From four to five days (intrinsic). 7. Period of Communicability. — Probably as late as the eighth day of illness. 8. Methods of Control. The Injected Individual. — (a) Diag- nosis : Clinical manifestations. (b) Isolation: In a screened room. (c) Immunization: None. (d) Quarantine: None. (e) Concurrent Disinfection: None. (/) Terminal Disinfection : Fumigate to get rid of mosquitoes. General Measures. — Same as for Yellow Fever. TYPHUS FEVER i. Infective Agent. — Unknown. 2. Source of Infection. — Typical and atypical human cases. 3. Portal of Exit. — In blood abstracted from patients. 4. Route of Transmission. — By the agency of the human body or clothes louse, Pediculus vestimenti (Fig. 80). The virus appears to have an extrinsic incubation period in the louse of at least four days. 5. Portal oj Entrance. — Through puncture wounds in the skin made by lice, into the subcutaneous tissues. 6. Incubation Period {Intrinsic). — From five to twenty days, usually twelve days. 7. Period oj Communicability. — Probably until one or two days following the return of patient's temperature to normal.' 8. Methods of Control. The Infected Individual.- — (a) Diag- nosis: By clinical manifestations. The Felix- Weil agglutina- tion reaction is reported as of value. (b) Isolation: Destroy all vermin on the body of the patient, transfer to vermin free clothing and place in a vermin free room. All attendants should wear vermin proof clothing. (c) Immunization: None. (d) Quarantine: Of those exposed, or of susceptibles for twelve days after last exposure. (e) Concurrent Disinfection: None. iq8 PRACTICAL PREVENTIVE MEDICINE (/) Terminal Disinfection: Destroy all lice, together with their eggs, on the patient's body if not already done. Destroy Fig. 79. — Screened water barrel, Havana. (Gorgas, "Sanitation in Panama," Appleton's.) Fig. 80. — Pediculus vestimenti. L.: female (X about 25). {Castellani and Chalmers, "Manual of Tropical Medicine," Wm. Wood and Co.). all vermin and eggs on the clothing returned to the patient. Free the isolation quarters of all vermin. General Measures. — Delousing of persons, clothing and prem- DISEASES TRANSMISSIBLE BY INSECTS 199 ises during epidemics, or when individuals have come into or have been brought into an uninfected place from an infected community. (Figs. 81, 82.) Fig. 81. — Delousing equipment of the Santa Fe Railroad. (Am. Jour. Pub. Health, 7-8.) EUROPEAN RELAPSING FEVER i. Infective Agent. — Spironema recurrentis {Syn. Spirillum obermeirii) . 2. Source of Infection. — Typical and atypical human cases. 3. Portal of Exit. — In the blood abstracted from patients. 4. Route of Transmission. — By the agency of the common bed bug, Cimex lectularius. (Fig. 83). The duration of the period of extrinsic incubation is unknown. Possibly also by body lice. 5. Portal of Entrance. — Through puncture wounds made in the skin by bugs and lice, and also through abrasions made by scratching, into which have been rubbed the body juices of crushed bugs. 6. Incubation Period. {Intrinsic). — From two to twelve days. 200 PRACTICAL PREVENTIVE MEDICINE 7. Period of Communicability.— Unknown. Regard a patient as possibly infective until recovery is complete. 8. Methods of Control. The Injected Individual. ^-{d) Diag- nosis: Clinical manifestations confirmed by the observation of the spirillum in blood smears taken during relapses. a -2 •°3 3 .§ §1 (&) Isolation: Same as for typhus. (c) Immunization: None. (d) Quarantine: Of exposed susceptibles for twelve days after the last exposure. DISEASES TRANSMISSIBLE BY INSECTS 201 (e) Concurrent Disinfection: None. (/) Terminal Disinfection: Same as for typhus. General Measures. — Same as for typhus, extending the ac- tivities to include the bed bugs. Fig. 83. — Cimex lectularius. a. Adult female, gorged with blood; b, same from below; c, rudimentary wing-pad; d, mouth-parts — all enlarged. (Marlait, Bull. 4, Div. Rnt.). REFERENCES Ross: The Prevention of Malaria. Quinine Prophylaxis for Malaria. Reprint 454, Public Health Reports. Oiling as an Anti-Mosquito Measure. Reprint 260, Public Health Reports. Drainage as an Anti-Malarial Measure. Reprint 258, Public Health Reports. Malaria Control: Public Health Bull. 88, U.S.P.H.S. Yellow Fever: its epidemiology, prevention and control. Supplement 19, Public Health Reports, U.S.P.H.S. The Administration of a Yellow Fever Campaign. Supplement 15, Public Health Reports, U.S.P.H.S. Boyd: The Delousing Measures of the Santa Fe Railway System. Am. Jour. Public Health, Vol. 7, 667. Field Identification of Malaria Carrying Mosquitoes. Supplement 32, Public Health Reports. Suggestions on How to Screen the Home to Keep Out Effectively the Mos- quitoes Which Spread the Disease. Reprint 170, Public Health Reports. Anopheline Surveys: Methods of Conduct and Relation to Anti-Malarial Work. Reprint 272, Public Health Reports. Methods of Destroying Lice. Reprint 293, Public Health Reports. Destroying Lice on Typhus Fever Suspects. Reprint 370, Public Health Reports. The Yellow Fever Mosquito. Farmer's Bull. 347, U. S. Dept. Agriculture. Malarial index work. Reprint 159, Public Health Reports. 202 PRACTICAL PREVENTIVE MEDICINE Typhus Fever. Reprint 271, Public Health Reports. Malaria in the United States. Reprint 277, Public Health Reports. Carbon Tetrachloride as a Delousing Agent. Reprint 489, Public Health Reports. The Transmission of Typhus Fever, etc. Reprint 74, Public Health Reports. Studies on the Virus of Typhus. Reprint 82, Public Health Reports. The Felix-Well reaction as a laboratory test in the diagnosis of typhus fever. Public Health Reports, Vol. 34, p. 2446. CHAPTER XXII LOWER ANIMALS AS SOURCES OF INFECTION FOR MAN The lower animals, both wild and domesticated, suffer from a number of infections whose agents are transmissible to man. The more important are the following: Frequency Disease Animal host A. Transmission regular i. Bubonic Plague. Rats, by the agency of or at least frequent. fleas. 2. Rabies. Dogs and other carnivora. 3- Anthrax. Sheep, cattle and horses. 4- Trichiniasis. Swine. 5- Malta Fever. Goats. 6. Rocky Mt. Fever. Ground squirrels by ticks. 7- Tape Worms. Cattle, swine and dogs. B. Transmission limited. 8. Cow pox. Cattle. 9- Bovine tuberculosis. Cattle. 10. Glanders. Horse, donkey and mule. 11. Paratyphoid. Cattle and swine. 12. Foot and mouth dis- ease. Cattle and swine. 13. Fungi of favus and ring-worm. Mice and cattle. Because of their rarity in man, or their triviality as causes of mortality, we shall ignore certain of these infections and confine our attention to five. These infections are transmitted to man by varying routes, the only common feature being the fact that man is not the normal host of the infective agent. PLAGUE (BUBONIC AND PNEUMONIC) 1. Infective Agent. — Bacterium pestis. 2. Source of Infection. — Typical and atypical plague (acute and chronic) in rats and other rodents, including the native ground squirrels in California. In pneumonic plague man 203 204 PRACTICAL PREVENTIVE MEDICINE serves as the source of infection. The disease normally, how- ever, is one of rodents. 3. Portal of Exit. — The blood of infected rats abstracted by fleas, or the sputum of pneumonic plague patients. 4. Route of Transmission. — In bubonic and septicemic plague the bacillus is conveyed from rat to man or from rat to rat or other rodent, by the agency of either the tropical rat flea [Loemopsylla ckeopis) or the temperate zone rat flea (Cerato- phyllas fasciatus) (Fig. 84). Their action is purely mechanical. The plague bacilli produce an intestinal obstruction in the flea, so that an infected flea when attempting to feed regurgi- Fig. 84. — The European rat flea (Ceratophyllus fasciatus): adult female. Greatly enlarged. (Bishopp: Bull. 248. U. S. Dept. of Agriculture.) tates plague bacilli from his stomach into the punctured wound. Bed bugs {Cimex lectularius) may also transmit the bacilli. In pneumonic plague the bacilli are transferred from man to man by direct or indirect contact. 5. Portal of Entrance. — The fleas may introduce the bacilli into the subcutaneous tissues of any part of the body, usually into the lower extremities. In pneumonic infection the bacilli are introduced into the body either through the mouth, nose or conjunctiva. 6. Incubation Period. — Commonly from three to seven days, though sometimes prolonged to eight or even fourteen days. 7. Period of Communicability. — (a) Man: Until convales- cence is well established, period undetermined. LOWER ANIMALS AS SOURCES OF INFECTION FOR MAN 205 (b) Rat: In chronic or latent cases the infectivity may be prolonged, but the period is uncertain. 8. Methods of Control. The Infected Person.— (a) Diagno- sis: Clinical manifestations confirmed by bacteriological ex- amination of blood, glandular exudate or sputum. (b) Isolation: i. Bubonic plague: Hospitalize if possible, place patient in a vermin free, screened room. 2. Pneumonic plague: Rigid isolation must be employed and attendants must exercise great care for their own protection. Masks should be worn. (c) Immunization: Yersin produced a serum by the in- jection of horses at first with a plague vaccine and later com- pleting the immunization by the use of living cultures^ The therapeutic value of the serum is appreciable. Active immu- nization with Haffkine's vaccine apparently confers protection. The Indian experience appears to indicate that the likelihood of subsequent infection after its use is reduced four fifths, while among the proportion who do contract infection, the chances of recovery are much increased. It should be administered to those persons whose activities favor their exposure. (d) Quarantine: Of contacts for seven days. (e) Concurrent Disinfection: Of all discharges and articles soiled therewith. (/) Terminal Disinfection: Thorough cleaning followed by thorough disinfection. General Measures. — (a) Extermination of rats and vermin within the infected area, paying especial attention to the brown or Norway rat by employing : 1. Fumigation with HCN, S0 2 , CO or CS 2 . 2. Trapping. 3. Poisoned bait. (b) Rat exclusion. 1. By rat proofing homes, outhouses, and business buildings (Figs. 86, 87, 88, 89). m m 2. By removing accumulations of refuse in which rats can harbor, and of garbage upon which they can feed. 3. By exterminating rats on ships. 4. By preventing rats on ships from coming ashore, or those on shore from entering ships (Fig. 90). The marine migrations of rats, accomplished by the aid of shipping, have in the last twenty five years distributed plague over the entire world. (c) Flea destruction by fumigation. This should be em- ployed in infected foci. 2o6 PRACTICAL PREVENTIVE MEDICINE Pig. 85. — Generalview of stable and junk house from second floor. Two plague rats were trapped here. On demolition 86 rats were killed. (Public Health Reports.) Fig. 86. — Model showing construction details which permit rat infestation. (Suppl. 27, Public Health Reports, U. S. P. H. S.) LOWER ANIMALS AS SOURCES OF INFECTION FOR MAN 207 (d) Delimitation of an infected area: General rat trapping operations should be carried out all over an infected area. All rats caught and all found dead should be examined for evi- Fig. 87. — Rat-proofing lumber by elevation on concrete pillars. (U. S. P. H. S.) dence of plague infection. The locality where each infected rat is found should be regarded as a focus of infection. Since Fig. 88. — Site of human plague in Puerta de Tierra. Rat proofed by concrete walls and floor. (P. H. Rep., June 6, IQ13O permanent measures of rat exclusion and eradication are ex- pensive and procede slowly, it is not always practicable, in the face of existing plague, to enforce these generally with the hope 208 PRACTICAL PREVENTIVE MEDICINE of eradicating the disease. A more practicable method is to confine the earliest operations, at any rate, to the infected foci Pig. 89. — Site where a plague rat was found, after elevation. Building formerly tight to the ground. {P. H. Rep., June 6, 1913.) Pig. 90. — The rat guards on the hawsers prevent rats entering or leaving the ship by this route. The ship should also be breasted from the wharf. until the disease is brought under control. The method de- veloped by Heiser in Manila for this purpose is as follows: LOWER ANIMALS AS SOURCES OE INFECTION FOR MAN 209 Five radiating equidistant lines are drawn from each point where a plague rat is found. Starting at the center, rat catch- ing operations are carried out along each. The most distant points along each line at which plague rats are found are con- nected by lines. Thus the circumference of the infected area is outlined (See Fig. 90a). As a rule its radius is seldom more than a few blocks from the original focus. Rat catching is then be- gun along the periphery and proceeds toward the center, after Pig. 90a. -Isolated plague-infested center, Manila, P. I. and Public Health, U. S. P. H. S.) (From Heiser; Rat which rat proofing operations are begun at the periphery and proceeds centrally. Thus the rodents in each focus are ex- terminated and the place made uninhabitable for them. This method has not been employed in combatting plague in the United States. (e) In California considerable effort is being made to eradi- cate the ground squirrels in infected rural areas by use of poi- soned grain, trapping, and asphyxiation of the squirrels in their burrows by carbon bisulphide. 14 2IO PRACTICAL PREVENTIVE MEDICINE (/) House to house inspection for the detection of unreported cases may be necessary. All dying during the epidemic should be autopsied. (g) Cremation or burial in quick lime is advisable. ROCKY MOUNTAIN SPOTTED FEVER i. Infective Agent. — Unknown. 2. Source of Infection. — Ground squirrels and other rodents of the western inter-mountain region of the United States. 3. Portal of Exit. — Blood of infected animals abstracted by ticks of the genus Dermacentor. 4. Route oj Transmission. — By bites of ticks (Dermacentor andersonii, or venustus. (See Fig. 91), which have fed on infected ground squirrels. Probably a biological transmission. 5. Portal oj Entrance. — Into the subcutaneous tissues through the bite wound. 6. Incubation Period. — Three to ten days, usually seven days. 6. Incubation Period. — Three to ten days, usually seven days. 7. Period oj Communicability. — Unknown. 8. Methods of Control. The Injected Person. — (a) Diag- nosis: By clinical manifestations in areas where the disease is known to be endemic. (b) Isolation: None. (c) Immunization: None. (d) Concurrent Disinfection: None, but destroy any ticks that may be on the patient. (e) Quarantine: None. (J) Terminal Disinfection: None. General Measures. — (a) The wearing of tick proof clothing by those in endemic areas, and following the practice of search- ing the body each day for ticks. (b) Destroying ticks on limited zones in infected areas by clearing, and burning vegetation in rotation. (c) Grazing sheep on infected areas. The ticks attach themselves to the sheep, become enmeshed in the wool and perish. (d) Dipping of the other domestic animals of infected areas in arsenical solutions. (e) Destruction of ground squirrels, chipmunks and other rodents in infected areas by poisoned grain, by CS2 and by trapping. LOWER ANIMALS AS SOURCES OF INFECTION FOR MAN 211 Fig. 91. — The RockyMountain spotted-fever tick, Dermacentor venustus.^ 1. " Deposited-out " female with eggs. 2. Unengorged larva. 3. " Deposited- out" female, frontal view. 4. Engorged larva. 5. Engorged female, dorsal view. 6. Unengorged female, dorsal view. 7. Male, dorsal view. 8. Male, ventral view. 9. Unengorged female, ventral view. (Hooker, Bishopp and Wood, Bull. 106, Bureau of Entomology, U. S. Dept. of Agriculture.) 212 PRACTICAL PREVENTIVE MEDICINE RABIES i. Infective Agent. — Unknown, a filterable virus. 2. Source o] Infection. — Typical and atypical cases and incu- batory carriers in dogs, and other carnivorous animals. 3. Portal oj Exit.- — In the saliva of infected animals. 4. Route oj Transmission.- — Inoculation with the saliva of infected animals, through wounds or abrasions of the skin and mucosa, almost always by bites or scratches. 5. Portal oj Entrance. — Through the subcutaneous tissue to the terminal nerve fibers. 6. Incubation Period. — Variable, seldom less than four weeks and occassionally six months or longer. 7. Period oj Communicability. — For perhaps two weeks prior to the manifestation of symptoms and throughout the clinical course of the disease. 8. Methods of Control. — (a) Diagnosis (in animals). — Clini- cal manifestations of animals, confirmed by the rinding of Negri bodies in the brain, or by successful animal inoculations with such a brain. (b) Isolation (of Patient). — None, if patient is under adequate medical supervision and the immediate attendants are warned of the possibility of inoculation by human virus. Animals which are suspected of being rabid and which have bitten or exposed a person to infection, should not be killed, inasmuch as the laboratory confirmation of the suspected diag- nosis may be rendered difficult or time consuming. Such ani- mals should be confined in rigid isolation and closely observed. If actually rabid, death will occur within ten days and the diagnosis can be confirmed by the clinical course and labora- tory examination. If the animal is alive at the end of this period the question of rabies is eliminated. This precaution does not endanger the patient through too great delay in be- ginning the Pasteur treatment. (c) Immunization. — The administration of active immuniza- tion (Pasteur treatment) after exposure to infection by inoculation. The Pasteur treatment should be administered under the following circumstances: A. From a diagnosis of rabies in the biting animal based on one or more of the lollowing data: (1) Clinical manifestations, (2) Negri bodies, (3) Inoculation, or, B. On suspicion, where the biting animal is at large but manifested suspicious symptoms. LOWER ANIMALS AS SOURCES OF INFECTION FOR MAN 213 Various methods have been devised for the attenuation of the rabies virus, but those is most general use closely follow the technique developed by Pasteur. The rabic virus derived from carnivorae is attenuated for man by successive passages through rabbits, until its incubation period becomes constant. It is then known as fixed virus, and has an incubation period of six to seven days when inoculated intracerebrally into rabbits. The spinal cord of a rabbit dying of fixed virus infection is asepti- cally removed intact and dessicated in a jar over sticks of caustic soda, producing a further attenuation. From day to day, up to the 8th day of dessication, pieces of dried cord repre- senting about 1 cm. of the fresh cord are removed to glycerine and designated as one, two or three day cord, etc., according to the extent of the dessication to which they have been sub- jected. Under refrigeration, these remain potent about one month. For administration the dried cord is further prepared as follows: A piece of the dried cord is washed in saline to remove the glycerine, and ground in a small mortar until homogenous. Then drop by drop two and five tenths c.c. of saline are added and thoroughly mixed with the cord until a homogenous sus- SCHEMA OF THE PASTEUR TREATMENT Day of treatment Age of dried cord Amount injected I 8-7-6 2-5 2 4-3 2-5 3 5-4 2-5 4 3 2-5 5 3 2-5 6 2 2-5 7 2 2-5 8 1 2-5 9 5 2.5 10 4 3-5 11 4 2-5 12 3 2-5 13 3 2-5 14 2 2-5 IS 2 2-5 16 4 2-5 17 3 2-5 18 2 2.5 19 2 2-5 20 3 2-5 21 2 2.5 For children the doses of the stronger viruses are reduced. 214 PRACTICAL PREVENTIVE MEDICINE pension is secured. This is the material for injection. The site of election is the subcutaneous tissue of the abdominal wall, which is prepared by painting the skin with iodine. With the vaccine distributed bythe U. S. P. H. S., the course of treatment covers twenty five injections given over a period of twenty one days. The schedule followed in the intensive treatment of adults is as given in the preceding table. (d) Quarantine. — Of dogs transported from infected to unin- fected areas for six months. (e) Concurrent Disinfection. — Of patient's saliva and objects contaminated therewith. Pig. 92. — Proper and improper muzzling of dogs. The muzzle on the right hand dog is ineffective, as it may be easily slipped from position. (U. S. P. H. S.) if) Terminal Disinfection. — Thorough cleaning. General Measures. — {a) Muzzling of dogs when on public streets or in places to which the public has access (Fig. 92). (b) Detention and examination of dogs suspected of having rabies. Detention should be maintained ten days. If death occurs search should be made for Negri bodies. (c) Provision for the immediate anti-rabic treatment (active immunization) of persons bitten by dogs or other animals suspected or known to have rabies. The wounds should be cauterized with fuming nitric acid as soon after their infliction as possible. LOWER ANIMALS AS SOURCES OF INFECTION FOR MAN 215 ANTHRAX i. Infective Agent. — Bacillus anthracis. 2. Sources oj Injection. — Cases in cattle, sheep and horses. 3. Portal oj Exit. — In extra vasated blood. 4. Route oj Transmission. — By the hair, hides and feces of infected animals or objects such as soil or dust, contaminated therewith. It must be borne in mind that this is a spore forming organism which can survive the action of sunlight and desiccation for prolonged and indefinite periods, such as months and years. Hence contaminated intermediate objects may serve as fomites. 5. Portal of Entrance. — By inoculation of the spores into the subcutaneous tissues by scratches, wounds or the inhalation of spores in dust. 6. Incubation Period. — Within seven days. 7. Period of Communicability. — During the febrile stage and until the lesions have ceased discharging. Infected hair and hides of infected animals may communicate the disease for many months after the slaughter or skinning of the animals, and even after the curing of the hide or hair, unless previously disinfected. 8. Methods of Control. The Infected Individual. — (a) Di- agnosis: Clinical manifestations confirmed by bacteriological examination. (b) Isolation: Until the lesions have healed. (c) Immunization: No highly effective method for the immunization of man has been developed. The anti-anthrax serum is well worth a trial. Normal beef serum is said to give good results. (d) Quarantine: None. (e) Concurrent Disinfection: Of the discharges from the lesions and of objects soiled therewith. (0 Terminal Disinfection: Thorough cleaning. General Measures. — {a) Animals ill with a disease presum- ably anthrax should be placed immediately in the care of a veterinarian. Proved cases should be promptly killed and the carcass destroyed by cremation. (b) Isolation: Only of suspected cases. (c) Active Immunization: Of exposed animals under govern- mental supervision. The double vaccine, consisting of two separate inoculations with doses of graded virulence, is in most general use. 2l6 PRACTICAL PREVENTIVE MEDICINE (d) Post mortem examinations should be made only by a veterinarian or bacteriologist. (e) Milk from an infected animal should not be used. (/) Control of and the disinfection of sewage effluents and trade wastes from factories and premises where spore infected hides or hair are known to have been worked up into manu- factured articles. (g) A physician should be employed by every company hand- ling raw hides or hair, or else such companies should operate Fig. 93. — Wool sorting. In wool manufacturing centers occupational anthrax is commonly known as "wool-sorters' disease." (Bull. 205, Bur. Lab. Stat.) under the direct supervision of a medical representative of the health department. (k) Every employee handling raw hides, hair or bristles who has an abrasion of the skin should immediately report to a physician. (i) All employees in such establishments should be personally instructed in the necessity for personal cleanliness. (j) Tanneries and woolen mills should be provided with proper ventilating apparatus so that dust can be promptly removed. (k) All hair, wool, and bristles originating in known infected LOWER ANIMALS AS SOURCES OF INFECTION FOR MAN 217 centers should be disinfected before they are cured or sorted (Fig. 93). (/) The sale of hides from animals dying from anthrax should be prohibited. (m) Hides of unknown origin should be disinfected. Means of disinfection that will not interfere with the desirable proper- ties of leather are not available. The following is the least objectionable method: Immerse the hides in i per cent, hydrochloric acid and 8 per cent, sodium chloride for 6 hours at a temperature of 40°C. Then neutralize with sodium carbonate and wash. (n) Workmen should be instructed to avoid touching blood clots on hides or hair. TETANUS i. Infective Agent. — Bacillus tetani. 2. Source of Infection. — Herbivorous animals, particularly horses and mules. 3. Portals of Exit. — The feces of such animals, rarely the dis- charge from infected wounds. 4. Route of Transmission. — Animal manure and objects and soil contaminated with animal manure. The spores of the organisms are very resistant and can survive for indefinite periods outside the body. Hence fomites transmission occurs. 5. Portal of Entrance. — Subcutaneous introduction of spores into wounds, cuts and abrasions, usually through their con- tamination with soil or manure, hair, etc. 6. Incubation Period. — Six to fourteen days, usually nine. 7. Period of Communicability . — The patient is not a source of infection, except in rare cases where the wound discharges are infective. On the other hand, some horses are chronic carriers. 8. Methods of Control. The Infected Individual. — (a) Diag- nosis: Clinical manifestations which may sometimes be con- firmed bacteriologically. (b) Isolation: None. (c) Immunization: Passive protection, secured by the ad- ministration of antitoxin, should be employed. The antitoxin has given the best results as a prophylactic agent. As a result of recent military experience the folllwing rules should be fol- lowed in its administration: 1. Every wounded person should receive at least 500 units 2l8 PRACTICAL PREVENTIVE MEDICINE prophylactically. This dose should be repeated on the 7th and 14th days thereafter. 2. Repeat the doses at more frequent intervals if there is any reason to fear tetanus. 3. Repeat injections forty eight hours prior to any secondary operation. 4. If tetanic manifestations develope, the subcutaneous and intramuscular routes of injection are preferable. Daily doses of at least 10,000 units should be given and continued well into convalescence. The injections should be given at different depths and at several points in the muscle tissue on the injured side, if an operation is contemplated. The importance of early prophylactic doses is indicated by the following results in 65 cases of tetanus: (a) Antitoxin administered within 24 hrs. of wounding: 43 cases, each receiving 500 units; 62.7 per cent, fatal, 37.2 per cent, recovered. (b) Antitoxin administered after 24 hrs. of wounding: 23 cases, each receiving 500 units; 86.9 per cent, fatal, 13. 1 per cent, recovered. (d) Quarantine: None. (e) Concurrent Disinfection: None. (/) Terminal Disinfection: None. General Measures (Especially to Prevent Wound Contamination) . (a) Supervision of the practice of obstetrics, so that proper care is given to the care of the infant's cord (Trismus neonatorum). (b) Educational propaganda, along the lines of the "safety first" campaigns and "Safe and Sane" Fourth of July campaigns. (c) Prophylactic use of tetanus antitoxin when wounds have been acquired in regions where the soil is known to be heavily contaminated with manure, and in all cases whose wounds are ragged and penetrating. (d) Removal of all foreign matter from wounds as early as possible. (e) Governmental supervision of biological products, so that only potent antitoxin is distributed. REFERENCES The Rat and its Relation to Public Health. U.S.P.H.S. Anthrax as an Occupational Disease. Bull. 205, U. S. Bureau of Labor Statistics. LOWER ANIMALS AS SOURCES OF INFECTION FOE MAN 219 Outbreak and Suppression of Plague in Porto Rico. Reprint 130, Public Health Reports. Plague, its Geographic Distribution and Menace to the United States. Reprint 130, Public Health Reports. Rat Proofing the Public Docks of New Orleans. Reprint 259, Public Health Reports. Rat Proofing' and its Practical Application to the Construction and Repair of Dwellings and Other Buildings. Reprint 122, Public Health Reports. Rocky Mountain Spotted Fever: A report of its investigation and of meas- ures undertaken for its eradication during 1914. Reprint 251, Public Health Reports. Facts and Problems of Rabies. Bull. 65, Hygienic Lab. U.S.P.H.S. Investigations of, and Tick Eradication in Rocky Mountain Spotted Fever. Reprint 79, Public Health Reports. The Eradication and Prevention of Bubonic Plague. Reprint 88, Public Health Reports. Technique of the Laboratory Examination of Rats for Plague. Reprint 89, Public Health Reports. Post Mortem Diagnosis of Plague. Reprint 90, Public Health Reports. Rocky Mountain Spotted Fever. Reprint 96, Public Health Reports. A Squirrel Destructor. Reprint 98, Public Health Reports. Bubonic Plague: its eradication and prevention in urban communities. Reprint 209, Public Health Reports. Post-vaccination Tetanus. Reprint 289, Public Health Reports. How to poi-son rats. Public Health Reports, Aug., 191 2. CHAPTER XXIII OTHER ASPECTS OF INFECTIOUS DISEASE i. In the foregoing chapters we have considered a number of the infectious diseases of public health importance in the United States. These for the most part are diseases which are systemic in character and the losses we have considered have been direct losses either from sickness or death. There is another type of damage which these diseases may produce that is fully as important as the losses we have heretofore con- sidered, namely the sequelae. These consist of a permanent injury or impairment of function arising from the illness, as a consequence of which the individual may never be restored to the degree of physical efficiency existing before the illness, and while he may recover from the infection, the permanent damage may either assist in the development of other patho- logical processes which shorten life or reduce the economic efficiency of the individual. We will briefly consider the injuries of this character. But little quantitative data on this point are available, so the presentation will deal necessarily with generalities. In a study of nearly two thousand cases of typhoid fever, Dublin finds that cardiac disease and a lowered resistance to tuberculosis are the most important sequelae manifesting their effect within three years following recovery. He concludes that during this period the mortality is twice that among in- dividuals who have not had typhoid fever. It is usually con- sidered that with typhoid, ten per cent, of the cases have a fatal outcome. He points out that in addition, the sequelae which produce a fatal outcome increase this mortality very nearly by five per cent. The fact that an increased mortality from tuberculosis is observed is very important. Many of the acute infections so undermine the individual's resistance to a more chronic infection such as tuberculosis, to an extent that a heretofore latent infection becomes active or the nephritis appearing as a complication of scarlet fever may fail to clear up with convalescence, and remain as a permanent injury to the individual. Diphtheria toxin may permanently impair the OTHER ASPECTS OF INFECTIOUS DISEASE 221 nervous system, so that the post-diphtheritic paralyses are one of the most dreaded sequelae of any disease. Likewise the great popular horror of poliomyelitis arises from the disabling paral- ysis so common in those who recover. The greatest progress we have made with poliomyelitis in recent years has been in the intelligent orthopedic handling of these cases. The results are so striking and so beneficial that many progressive state health authorities are now following up all poliomyelitis cases and making provision for orthopedic relief. Similar disablement may follow cerebrospinal meningitis, together with deafness. Noticeable mental or nervous impairment may follow typhus fever or whooping cough. Gonorrheal infection of the geni- talia in either male or female is frequently responsible for sub- sequent sterility of the individuals, and where infection is transferred to the eye, permanent blindness may result. After the active infective stages of syphilis are past the individual may suffer great physical disability from the lesions of the tertiary and quaternary stages. It is therefore apparent that the ravages of those diseases are not sufficiently brought out by a study of the mortality or morbidity records alone. Another aspect of this subject is that of the so-called " focal infections" whose importance was first emphasized by Billings and his associates. Chronic infection localized in some ob- scure area of the body may be responsible for the production of acute rheumatism, chronic deforming arthritis, gonorrheal arthritis, malignant endocarditis, myositis, myocarditis, sep- ticemias of several types, certain infectious types of thyroiditis with or without hyperthyroidism, acute and chronic pancreatitis with or without glycosuria, gastric ulcer and cholecystitis. The situations in which the chronic infection is localized are most commonly the dental alveoli, the tonsils, the gall bladder, the appendix or a nasal sinus. From these locations bacterial emboli are thrown off into the circulation, and if the defenses of the body are diminished by overwork, exposure to cold, dissipa- tion, insufficient or improper food, unhygienic surroundings, injuries from former diseases (valvular scars) or trauma, some of the conditions mentioned may develop. The responsible micro-organisms are most commonly those of the pneumococcus- streptococcus group. From a public health standpoint these conditions do not come to the attention of the health authorities except in so far as they participate in mortality production. But from the standpoint of the practising physician they are a field of preventive medicine in which brilliant results may be 2 22 PRACTICAL PREVENTIVE MEDICINE secured by searching for the chronic focus of infection and effecting its removal. Disease prevention by the developement of an active arti- ficial immunization against the infective agent concerned, among all susceptibles in a given population, is our chief weapon in the control of certain infections such as small- pox, and a valuable adjunct in others. The maximum effi- ciency of such measures is only achieved where immunization is made compulsory and where furthermore, the requirement is enforced, so that a large part if not ali the people are pro- tected Unfortunately in civil life, compulsory vaccination has lead to a greater or less amount of opposition among a few bigoted persons who fortify their position by refering to the very small number of accidents and secondary infections fol- lowing the practice, and ignore the achievements in disease reduction that has followed the extensive employment of the method. This opposition in some localities has been so vigo- rous that authorities have been unable to enforce the provisions of laws requiring compulsory vaccination while in others the authorities are forced into a continuous fight to prevent the repeal of the statutory requirements. In many localities the situation is discouraging. Fortunately the situation has a redeeming feature. Those who receive immunization receive protection, while those who do not, either through ignorance, carelessness or opposition run the far greater hazard of the virulent infection. Those who remain unvaccinated through opposition are sufficiently punished if they contact infection. Health authorities can in a large measure protect the individuals of the other groups by education of the public in the advan- tages of vaccination, by the distribution of free vaccine, and by providing for its free administration. Sufficient activity along these lines may very nearly achieve the same results as compulsory methods, without arousing hampering opposition. Practicing physicians can do a great deal in disease prevention by actively immunizing their clientel. REFERENCES Dublin: Typhoid Fever and its Sequelae. American Journal Public Health, V, pp. 20, 1915. Billings: Focal Infection: its broader application in the etiology of general disease. Journal Amer. Medical Association LXIII, 899, 1914. SECTION II DEFICIENCY DISEASES CHAPTER XXIV FOOD REQUIREMENTS: PRODUCTION AND RETAIL i The activities of the cellular tissues of the body require that the necessary material for growth, for renewal of the worn tissues and for energy be supplied. This material constitutes food From it the body liberates the necessary energy and secures new material for replacement purposes. Cellular activity is in different directions and for each type of activity different raw materials must be furnished. The most impor- tant raw materials which the body requires are protein food and certain mineral salts. The importance of protein arises from its nitrogenous content and hence it serves chiefly in repair and new growth, and to a lesser extent as a source of energy. The energy requirements are chiefly met by carbonaceous foods. The mineral salts are required to maintain tonicity of the body fluids, to build up the solid tissues, to form hemoglobin and tor other purposes. . The determination of the value of any given substance as a food is not a simple matter. Several different aspects must be considered. First perhaps, must be considered the percentage chemical composition of the substance. It must be assayed to determine its value in terms of food constituents, such as pro- tein, carbohydrates, fats and inert material. A second test to determine suitability is of a physical character, and enables us to judge the value of the food stuff as a fuel or source of energy. It is usually calculated from the results of the chemical analysis by the employment of the following factors, and is expressed in calories: i gm. of protein will produce 4- 1 calories i gm. of carbohydrate will produce 41 calories 1 gm. of fat will produce 9-3 calories 223 224 PRACTICAL PREVENTIVE MEDICINE However, since different food stuffs are not consumed in the body to the same degree, those factors will not always give an accurate idea of the value of a food as fuel. Next one must consider the food stuff from the body's standpoint. It must be one which is capable of digestion and absorption by the body, and of meeting the body's needs. Different individuals are capable of utilizing different materials to different degrees. In general 92.6 per cent, of protein; 94.4 per cent, of carbohy- drate and 97 per cent, of fat are absorbed. Some few, such as sugar are practically entirely absorbed. A fourth and equally as important guide to judgment is the knowledge whether a given food stuff can be obtained at a reasonable cost. In general the following represents what may be considered a standard in the United States for the proportion in which the different food elements should be represented in the diet of adults each day. Protein 125 gms. X 4 . 1 = 512.5 calories Carbohydrates.... 400 gms. X 4.1 = 1640. calories Fat 125 gms. X 9.3 = 1161.5 calories Some variation in these proportions can be made without in- jury but a certain amount of protein is absolutely necessary, though the exact limit is not known. A further important factor in considering the protein element is whether its content of amino acids is of the one or more types which the body can rebuild into its own protein. If the amino acids are unsuitable, the protein present is useless. Of the food consumed, less than one-sixth furnishes energy for work, the balance being lost as heat. In this respect the body's requirements and use of food are similar to the fuel consumption of an engine. Similarly more work requires more food. An average adult male of 150 pounds weight engaged different activities has approximately the following daily fuel requirements: Resting in bed 2000 calories Resting in a chair 2230 calories Light work 2600 calories Moderate muscular work 3100 calories Severe muscular work 35°o calories The energy for the extra work is chiefly supplied by the car- bonaceous foods. 2. Food is essential to life and because of this requirement, FOOD REQUIREMENTS, PRODUCTION AND RETAIL 225 food production everywhere is a fundamental industry and is the principal basis of agricultural pursuits. From the standpoint of raw materials or source, food stuffs are either animal or vegetable in origin. From a hygienic standpoint, the animal foods are of greater importance than the vegetable, as has been shown in Chapter XIX. With the animal foods we can group meat, fowl, fish, shellfish, crustaceans, insects and their products, eggs, milk and dairy products, animal fats and gelatine. The vegetable foods comprise cereals, vegetables proper, fruits, sugar, gums, vegetable oils and fats. While the production of these food stuffs is the basis of agriculture and fishing pursuits, yet many as produced are not suitable for im- mediate use as food, or if suitable they require treatment to remove bulky, inert, and useless material, or to preserve them suitably for transportation. Around these processes have grown up a host of secondary industries. It is apparent therefore that industries based upon food stuffs are at the foundation of our economic life, as the need for food is at the foundation of our physical life. 3. In connection with the handling of food stuffs, and the development of various technical processes in their treatment, certain practices arose, many of which were fraudulent in char- acter and a few perhaps inimical to health, which the Federal and State governments have endeavored to suppress by means of the so-called Pure Food Legislation. These objectionable practises are commonly known as adulterations and according to most legislation are classified as follows: (a) Mixing the material with foreign substances to reduce or lower, or injuriously affect the quality or strength, as for example the mixing of water with milk. (b) The substitution of one substance for another, either wholly or in part, such as the employment of cotton seed oil for olive oil. (c) The removal of any valuable constituent either wholly or in part, as for example the skimming of cream from milk. (d) The treatment of the food stuff to conceal damage or inferiority, as for example the addition of sulphites to old meat to give it a bright red color. (e) The presence of added deleterious ingredients, injurious to health. The so-called chemical preservatives come under this head, such as borax or formalin. (/) Or the retail of food stuffs that are wholly or in part de- composed, filthy, or putrid. 15 226 PRACTICAL PREVENTIVE MEDICINE It can readily be seen that for the most part the practices grouped here deal practically with the cheating of the purchaser or consumer by unscrupulous dealers, and as such more directly affect the pocket book than it does health. 4. Most food stuffs are as well adapted to the needs of various other forms of life as they are to man's, particularly to micro- organisms. As a consequence of the activity of these, most food stuffs readily spoil or undergo decomposition. One of the greatest forward steps in our economic progress has been the dis- covery and application of means whereby decomposition may be prevented. Thus seasonable and perishable foods may be kept from years of plenty to years of scarcity, perishable foods may be transported to distant markets, and dense concen- trations of population at a great distance from their source of food supply are possible. The great cities of our day have developed progressively with the development of food preservation. The object of food preservation is to preserve the nutritive value of the food stuffs and their palatability for an indefinite period and at least until the next season. Food stuffs designed for preservation should be fresh and wholesome in their raw state. The methods of preservation are all designed to inhibit the activity of the micro-organisms which produce the changes of decomposition. Among these we may mention refrigeration and freezing, drying, salting, smoking, canning by the aid of heat (sterilization), preserving by the use of strong sugar solu- tions, and the use of antiseptic chemicals, such as vinegar and spices. 5. Of equal if not of greater importance with production from a hygienic aspect, are the conditions of retail sale and consump- tion of food stuffs, particularly from the standpoint of the transmission of infective agents. Food stuffs on the retail market are as a rule but a few hours away from their consump- tion, so that if contaminated with infective agents the chances for the survival of the latter and their successful invasion of the consumer are excellent. From an esthetic standpoint, the physical appearance of a retailer's wares influences the purchases a customer will make. The two conditions we have mentioned are affected by the character of the retail establish- ment, its cleanliness, the number and variety of vermin present and whether food stuffs are protected from vermin as well as unnecessary handling by both clerks and prospective customers. And in this connection restaurants are of equal if not greater FOOD REQUIREMENTS, PRODUCTION AND RETAIL 227 importance than retail stores. Clerks, waiters, cooks, dish- washers, etc., may be typhoid carriers or in the active infective stage of venereal disease or other infection; or the knives, forks, spoons, plates, cups, etc. of eating houses may not be adequately cleansed between the services they render to suc- cessive patrons, so that infective agents survive upon them. In this capacity soft drink stands are of great importance. The ordinary methods of washing dishes, glassware and eating utensils employed in restaurants and eating houses are insuffi- cient to destroy infective agents present in the buccal secretions with which they are contaminated after use. Furthermore FlG. 94. — Dish-washing — a simple, efficient method of sterilizing the dishes {Overton and Denno, " The Health Officer.") they serve to distribute these over all other dishes which are being washed at the same time. The use of boiling water is the most practical method for effecting this sterilization. The dishes, etc., are given a preliminary cleaning in hot water sup- plemented with soap, or in soap suds, and then placed in a wire basket, which is dipped into a large kettle of boiling water kept constantly available for this purpose. This method of handling dishes possesses the additional advantage that no subsequent wiping is necessary. Or in the retail stores, food- stuffs many of which are ordinarily eaten without further heating or cooking, are exposed to flies, roaches, rats, mice, 228 PRACTICAL PREVENTIVE MEDICINE dogs, or the fingers of prospective customers. Thus their con- tamination with infective secretions may occur and infective agents upon them stand an excellent chance of reaching a new- host. Employees who have cases of diseases transmitted by contact in their families should be excluded from employment until it is ascertained they are free from infection and that they subsequently remain away from their infected household during its quarantine. CHAPTER XXV DISEASES DUE TO DIETARY DEFICIENCIES RELATION OF FOOD TO HEALTH The quantity of food required to maintain the body in vigor varies with the climate and season, clothing, occupation, work and exercise, the state of individual health, age, sex, and body weight. Modern conditions of food preparation frequently stimulate the appetite so that one consumes food far in excess of the body's requirements. When coupled with insufficient exercise the results are bad. When prolonged it may lead to such diatheses as obesity and gout, and even though these conditions may not be produced, the temporary effects, the congestion of the digestive tract, the intestinal stasis, all exert a reflex action upon the central nervous system with the pro- duction of headache, mental fatigue and lassitude. Conversely the lack of sufficient food is also deleterious. In the complete absence of food life can rarely be sustained over ten days. An insufficient diet has another important effect. Individuals who are poorly nourished have their resistive forces lowered to such an extent that they fall a ready prey to invasions by micro- organisms and the probabilities of a fatal termination are also much greater. This is illustrated by the severe epidemics which have so frequently been associated with famine. Associated with the question of an insufficient diet is the question of an unbalanced diet, by which we mean one in which the proper proportion of protein, carbohydrate and fat are not represented. Economically the parallelism of poverty and want in connection with these is sometimes very close, though we also see an unbalanced diet resulting from a perversion of appetite or inability, from other circumstances, to secure the necessary materials. Thus an anemia may be due to lack of meat, an excess of carbohydrates and fats may produce acne and eczema or an excessive concentration may produce con- stipation. In addition diseases such as pellagra and beriberi appear to owe their origin to an unbalanced dietary. We shall discuss these briefly later. Substances consumed as food may exert directly a toxic or 229 23O PRACTICAL PREVENTIVE MEDICINE injurious action on the body in various ways. Thus ignorant people may undertake to use naturally poisonous substances as food and suffer severely as a consequence, employing for ex- ample, toadstools, certain poisonous fish or plants containing toxic alkaloids. Through accidents in preparation or for commercial reasons, extraneous poisonous substances may be present in toxic amounts, such as the heavy metals, arsenic or formaldehyde. Or the food stuffs, while normally wholesome and harmless, may through some natural change become toxic, as for example the development of solanin in potatoes and of ergot in rye. Some will consume excessive quantities of alcoholic beverages, such as beer, wines or whisky, etc. Or lastly some individuals have iodiosyncrasies toward certain foodstuffs. The manifestations of these idiosyncrasies very much resemble an anaphylactic reaction. Among the food- stuffs for which these reactions have been noted, are straw- berries, certain sea foods, eggs, oatmeal and tomatoes. There are three deficiency diseases whose common character warrants their receiving especial attention, namely scurvy, beri- beri and pellagra. SCURVY, BERIBERI, AND PELLAGRA Definitions. — (a) Scurvy is an acute or chronic disease char- acterized by debility, mental apathy and anemia, with spongi- ness of the gums and ulcerations of the mouth, manifesting a tendency to hemorrhages into the subcutaneous tissues and from the mucous surface. (b) Beriberi is an acute or chronic disease characterized by changes in the nervous system, and particularly by a multiple peripheral neuritis, with an especial tendency to attack the nerves of the limbs, the pneumogastrics and the phrenics, with varying degrees of cardiac disturbances,, oedema, serous effu- sions and gastro-intestinal derangements. (c) Pellagra is an acute or chronic disease characterized by a peculiar erythema and dermatitis on those parts of the body exposed to the sun's rays, by salivation, dyspepsia, and diarr- hoea, and by nervous manifestations which may terminate in mental disturbances and paralysis. Geographic Distribution. — In general one may say that they are world wide, though varying in their relative prevalence, as shown in the following table which indicates their greatest in- cidence. DISEASES DUE TO DIETARY DEFICIENCIES 23I Scurvy Has prevailed in all Euro- pean countries. South- ern Asia, Australia, South Africa and Egypt and the United States Beriberi Common throughout the Orient, especially in China, Japan, the Phili- ippines, India, Africa and South America. Rare in the United States Pellagra Southern Europe, Italy, Spain, Orient, and the Southern United States. Incidence. — They may occur either as sporadic cases or in a wholesale prevalence simulating epidemic or endemic distribu- tion. Such latter instances usually occur among closely cir- cumscribed groups of people, such as soldiers at military posts or on campaigns, laborers at labor camps, exploring parties, sailors on long cruises, inmates of jails, penitentaries, insane hospitals and other similar institutions. Past Ideas of Etiology.— Widely different theories of their etiology have been held until recently and these we shall briefly review before passing to current knowledge. (a) Scurvy has been variously ascribed to : (1) a deficiency of potassium in the blood; (2) a decreased alkalinity of the blood, i.e., an acidosis; (3) to ptomaine poisoning; and (4) to a specific infection. (b) Beriberi has been ascribed to; (1) poisoning by arsenic or by oxalates; (2) to a deficiency of nitrogen, fat or phos- phorous; (3) a specific infection; or (4) as an unknown intoxica- tion. (c) Pellagra has been variously regarded as: (1) an intoxica- tion due to the consumption of spoiled corn; (2) as a specific infection, either transmitted by contact or by the agency of the small black flies of the genus Simulium; or as an intoxication due to colloidal silica. Some few perhaps still adhere to some of the foregoing views, but in general we believe that the majority of scientific men regard these diseases as having the following etiology. Present Views of Etiology.— (a) Scurvy (Hoist and Frohch) is found to be due to a deficiency of some essential constituent from preserved foods but which is present in all kinds of fresh food, both animal and vegetable. (b) Beriberi (Fraser and Stanton, Vedder, et al) is due to the removal in the process of milling and polishing rice or wheat, of certain substances present in the pericarp of the grain, which are necessary to life (Figs. 95, 96, 97, 98). About 1 gm. of 232 PRACTICAL PREVENTIVE MEDICINE this substance is present in one kilogram of rice and it may be extracted from rice millings by alcohol. By its employment dry beriberi and experimental polyneuritis of fowls may be cured. (c) Pellagra (Goldberger and Wheeler) is due to a diet devoid of meats or vegetable fats. It has been produced in 6 of n Fig. 95. Pig. 96. Fig. 97. Fig. 98. FiG. 95. — A highly milled or polished rice stained by Gram's iodine solution. The starch, being completely exposed, stains uniformly a dark blue. This rice will produce beriberi. Fig. 96. — An undermilled rice stained in the same way. The unstained areas show where the adherent pericarp has protected the starch from the action of the iodine. This rice will probably not produce beriberi. Fig. 97. — A sample of undermilled rice that contains still more pericarp. The use of this rice will surely prevent the development of beriberi. Fig. 98. — The unhusked groid or "palay." When the husks are removed by hand pounding, a rice like Fig. 97 or Fig. 96 is produced. {From Vedder, "Beriberi," Wm. Wood and Co., Publishers .) convicts by a five months diet of biscuits, cornbread, collards, grits, rice, fried mush, brown gravy, sweet potatoes, cabbage and cane syrup. Some are inclined to dispute the correctness of the diagnosis of pellagra among the subjects in this experi- ment. DISEASES DUE TO DIETARY DEFICIENCIES 233 Vitamins or Accessory Food Factors. — Based upon the dis- covery of the therapeutic value of rice milling extracts in the cure of beriberi, these diseases have been ascribed to the ab- sence of minute quantities of certain substances from the diet. Recent researches by Funk, McCallum and others have so far resulted in the recognition of two of these substances in food- stuffs, one of which is soluble in water, the other in fats. Their chemical nature is unknown. These are also designated fac- tors B and A respectively. The beriberi vitamin or antineuritic factor is identified with the water soluble factor B. Both of these are experimentally found to be essential for growth and maintenance. From the known relationship of scurvy to preserved foods, a third vitamin, an antiscorbutic factor, is assumed to exist in fresh vegetable food. To fat soluble A are attributed antirachitic properties. Thus in addition to possessing a knowledge of the protein, carbohydrate and fat content of a dietary, it is also necessary to consider its content of vitamines or accessory food factors. The utilization of these substances in the body is not certainly known, but Green con- siders their main functions concern the gross metabolism of food, probably principally in oxidative catabolism. The water soluble B is chiefly secured from grain (germ and pericarp), eggs, yeast and legumes (entire seed). The fat soluble A is chiefly secured in cream, butter, cod liver oil, egg yolk and green legumes. The antiscorbutic factor is chiefly found in cabbage, turnips, lettuce, cresses, tomatoes, oranges and citrus fruits, and to a lesser extent in potatoes and carrots. It is destroyed in any dried food. In general the vitamins are destroyed or lost by cooking, by overheating (milk), by laking out in boiling, by too prolonged desiccation or by discarding the outer covering of grains. The Individual Prevention and Cure of these Diseases. — (a) Scurvy: Among these groups where scurvy has appeared the disease has disappeared following the addition of either: (1) juice of fresh sweet limes or lemons; (2) infusions of malt, (3) sauerkraut, (4) milk or (5) fresh potatoes to the dietary. (b) Beriberi too has disappearaed or has not developed with diets having the following characteristics: reduction of the amount of rice or a substitution of unmilled for polished rice, and the addition of legumes and other vegetables. (c) According to Goldberger by increasing the amount of fresh animal food and legumes in the diet of the inmates of three institutions where pellagra has been prevalent, he has 234 PRACTICAL PREVENTIVE MEDICINE prevented its recurrance during a period of one year, even among those individuals who were pellagrins during previous years. Public Protection. — The problem of dealing with these dis- eases from a public standpoint is more difficult of attack than is the administrative control of communicable diseases, and prob- ably is more dependent upon popular education. (a) Beriberi can probably be publically controlled by placing a prohibitive tax on the sale of polished rice. (b) Pellagra on the other hand, is more difficult. An in- creased consumption of milk, eggs, legumes and fresh vege- tables, together with meats is necessary. To a large extent this requires an improvement in the economic condition of the wage earners to enable them to increase their living standards. Some of this can be accomplished by domestic gardening and chicken raising. ALCOHOLISM Thanks to national prohibition this disease will soon be a matter of historical interest in the United States. The con- sumption of alcoholic beverages for their stimulating effect is a world wide habit of long antiquity. The evils it produces are both directly and indirectly due to its agency, and are both hygienic and economic. The latter is outside our province to discuss. As a contributing factor it is of wide spread impor- tance in commercial prostitution and hence is an important factor in the dissemination of venereal diseases. The elimina- tion of alcohol will go far to reduce commercial prostitution and hence reduce the extent to which venereal diseases are trans- mitted. Directly it is chiefly of importance as a cause of mental disturbances or psychoses. It is the direct cause of Korsakoff's psychosis, alcoholic hallucinations, delerium tremens and alcoholic deterioration. It is a contributory cause to others. This group of psychoses are responsible for about twelve per cent, of all first admissions to hospitals for the insane, and in general are more common in males than females, and in those from cities as compared with rural inhabitants. It is uncer- tain whether alcoholism is a factor in the hereditary trans- mission of mental deficiency. REFERENCES Rosenau: Preventive Medicine and Hygiene, 3rd. Ed., pp. 516-659. Winton: Food Analysis. The Chemical Composition of American Food Materials. Bull. 28, Office of Exp't Stations, U. S. Dept. Agriculture. DISEASES DUE TO DIETARY DEFICIENCIES 235 Some Forms of Food Adulteration and Simple Methods for their Detection, Bull. 100, Bur. Chemistry, U. S. Dept. Agriculture. Care of Food in the Home, Farmer's Bull. 375. The Sanitary Construction and Equipment of Abattoir's and Packing Houses. Circ. 173, Bur. Animal Industry, Dept. Agriculture. Vedder: Beriberi. Marie: Pellagra. The Treatment and Prevention of Pellagra. Reprint 228, Public Health Reports. , „ . , Experimental Pellagra in the Human Subject Brought About by a Retncted Diet. Reprint 311, Public Health Reports. Pellagra: A Report on its Epidemiology. Reprint 120, Public Health Reports. . . Pellagra: The Value of the Dietary Treatment of the Disease. Reprint 353, Public Health Reprints. _ The Prevalence and Geographic Distribution of Pellagra in the United States. Reprint 106, Public Health Reports. Overton and Denno "The Health Officer" Chapter XXXIII. SECTION III OCCUPATIONAL DISEASES CHAPTER XXVI HAZARDS OF OCCUPATION In the pursuit of a livelihood wage earners are exposed to varying risks and hazards, some of which are peculiar to their occupation while others arise as a result of their own or some one else's carelessness. We shall consider briefly the more important of these. i. From the standpoint of the number and gravity of the hazards encountered the principal occupations of mankind may be grouped as follows: Occupational class Manufacturing and Mechanical Industries C. D. Transportation (railroad men and sailors). Construction Work. Mining and the extraction of minerals. Character cf hazards (a) Unsanitary home environment. (b) Employment in unhygienic sur- roundings. (c) Inadequate lighting and ventilation. (d) Inadequate toilet facilities. (e) Infection. (/) Dust, fumes and poisons. (g Unguarded, carelessy operated, or defective machinery, (/z) Fire hazards, increased air pressure. (a) (a) Same as above. Same as above. a) Unsanitary home environment. (b) Premature explosions. (c) Fire damp, fires and dust. d) Unguarded and defective machinery. (e) Fall of roof. (/) Poisons. (g) Underground work, excessive heat or moisture. 236 HAZARDS OF OCCUPATION 237 E. Agriculture, forestry and animal husbandry. (a) Unsanitary home environment. (b) Accidents from machinery and timber. (c) Infection from livestock. (a) Defective hygienic conditions. F. Mercantile and Clerical Pursuits. (b) Inactivity, fatigue. G. Individual service, public, pro- fessional and domestic (a) Xo distinctive hazards. From the foregoing it can be seen that different occupations vary in the number and variety of hazards encountered, some are common to many, others are peculiar tc a group. We shall next consider the principal individual hazards, their danger and the means of their amelioration. 2. Unsanitary Home Environment. — The development of manufacturing industries, mines, or construction enterprises is frequently in situations inconveniently distant from previously existing cities or towns, or the number of workmen required for the enterprise is far greater than the number of vacant homes available. For this reason large companies have frequently built residence towns or additions to existing towns to accom- modate their employees. Many of these towns and the dwell- ings which comprise them have been constructed with very little thought to the welfare of those who must occupy them. The houses may be illy lighted or ventilated, water supply and excreta disposal are inadequate, mosquito breeding is permitted and gross overcrowding may prevail. On the other hand many enlightened corporations have constructed towns of model dwellings. Some rural or agricultural homes are fully as bad or even worse than those in the slum districts of large cities. 3. Inadequate Ventilation. — Many industrial processes give rise to dust and fumes, some of which are poisonous. In the vicinity of furnaces and open flames the oxygen content of the air is frequently much below normal, and the air may also be very smoky. Under these conditions the air is certain to be very hot, or under other conditions may be excessively humid as well. For this condition exhaust ventilation is the best remedy, with the exhaust intakes placed close to the situations where dust or fumes are produced. 4. Inadequate Lighting. — Natural illumination is frequently insufficient. Artificial illumination is likewise frequently in- 238 PRACTICAL PREVENTIVE MEDICINE sufficient or improperly employed, so that the work is poorly illuminated or the light shines in the workmen's eyes. Where a blinding illumination must be tolerated goggles are necessary. 5. Excessive Heat. — The bad effects of excessive heat may be counterbalanced by the use of goggles, body shields, air blasts, fans and water sprays. The workmen exposed to excessive heat should have a short work day, and shower baths should be avail- able for their use when leaving work. 6. Fatigue and Inactivity. — Fatigue is the chief cause of accidents from carelessness and furthermore decreases produc- tion. It arises from laborious work, long hours, piece work, speeding up practices, monotony, constant standing or a con- stant strained position, the use of chairs or stools without backs, faulty postures, jarring operations, the pressing or hold- ing of objects against the body, eyestrain, loud noises, irregular hours of sleep and the absence of work variation or periods of relaxation. Similarly the inactivity of the sedentary worker induces fatigue. It is one of the most important problems in industrial hygiene. 7. Extremes of Humidity. — Sedentary work should not be done in a humid atmosphere. If the air be excessively dry, provision should be made for its humidification. 8. Dust affects the lungs, the skin, the eyes and the external auditory canal. Protection from it may be secured by the use of goggles, respirators, wet processes, exhaust ventilation and the avoidance of dry sweeping. Of the different dusts en- countered in industries, soil dust is the least harmful, then in order of increasing danger come flour and starch, soapstone and talc, wood dust, bran dust, coal dust, clay dust, shell dust, ore dust, mineral dust and stone dust. These dusts may be either poisonous or irritating. The latter have an important rela- tionship to industrial tuberculosis. The problem of dust will be considered later in more detail. 9. Poisons are encountered in industry as either fumes, gases, solutions, pastes or solids. The list includes lead, benzine, benzol, turpentine, brass or zinc fumes, acids, alkalies, wood alcohol, anilin oil, carbon bisulphid, antimony, illuminating and fuel gas, hydrogen sulphide, arsenic, phosphorous, mercury and cyanide. Industrial poisonings usually occur because the amount of risk is not appreciated either by the employees or the employer. In combating their danger it is frequently necessary to overcome the following handicaps: (1) an employer's policy of keeping the employees in ignorance of the poisons used; HAZARDS OF OCCUPATION 239 (2) misbranding of poisonous substances; (3) lack of instruc- tions or, (4) disregard of instructions; (5) absence of mechanical health appliances, such as adequate ventilation; (6) permitting employees to eat while at work or in the work rooms; (7) lack of personal cleanliness among employees; (8) lack of sufficient washing facilities; (9) absence of gloves and respirators; and (10) no change of clothing on leaving work. Each poison presents a different problem. These also will later receive more detailed consideration. Fig. 99. — Rotary shears before and after protecting. Notice — "Stop this machine when oiling, wiping or repairing." Tennessee Coal, Iron and Railroad Company. (Bull. 4, U. S. Steel Corp.) 10. Infections. — Infections may be contracted either from other workmen by the agencies of contact, or from the mate- rial handled. Wounds received while at work and improperly cared for may become seriously infected. Contact transmission is favored by overcrowding, by the use of common towels and drinking cups, absence of cuspidors and consequent spitting on the floors, by sweeping during working hours, and by mouth- ing objects handled by another. Agriculturists may become infected from sick livestock, while workers in hair and wool may become infected with anthrax from this material. A cer- tain degree of protection is afforded by first aid training, but 240 PRACTICAL PREVENTIVE MEDICINE still better in a manufacturing plant is a surgical emergency room with a trained nurse in charge, and a' supervising surgeon. ii. Unguarded or Defective Machinery. — This is one of the most potent sources of danger. The following moving parts of machinery should be protected by suitable guards so that hair, clothing, or the ringers may not be caught or the person crushed or mangled, viz.: gears, rolls (Fig. 99), belting, rope or chain drives, all horizontal belts or shafting less than seven feet from the floor, beltshifts or loose pulleys, clutches, shaft guards and set screws. Fly wheels and emery wheels should also be guarded, and the latter should be suitably connected -Mil r' a- -** n^— • • l"% V* ■'■-■ *v Pig. 100. — Concentrating plant Oliver Iron Mining Co. 32,000 feet of pipe for hand and guard rails were used in connection with platforms at this plant, giving safe access to all machinery. Guarded platforms. {Bull. 4, U. S. Steel Corp.) to an exhaust vent. Additional points for safety in factories are the following: (i) Glass panels on swinging doors in passage- ways, (2) ladders should have sharp points on their feet, (3) elevated platforms around machinery should be railed (Fig. 100), (4) saws of different types and planes should have suitable guards. Convenient provision should be made for the rapid shutting off of power in the event someone is caught. Similarly power of any sort should not be turned on, or machinery set in motion, unless it is known that no one is in a position to be injured. 12. Transportation Hazards. — Employees suffer from these more than passengers, while trespassers suffer the most. Acci- HAZARDS OF OCCUPATION 241 dents upon the railroad are mainly due to the following: Care- lessness,, lack of discipline, overwork, and the lack of safety devices. Passengers mainly suffer from derailment and collis- ions while employees suffer from accidents arising in coupling and uncoupling cars, and by falling from cars or engines. 13. Mining and quarrying have types of peculiar hazards such as fall of roof and explosions. The former can largely be elimi- nated by proper timbering. Explosions are due to different causes. Float dust containing 10 per cent, or more of volatile matter is very explosive when brought in contact with a naked flame. It should either be wet down or covered with stone dust. Fire damp (CH 4 and O) explodes either from a naked flame or Fig. ioi. — Rescuing fellow-workman. Miners equipped with breathing ap- paratus. (Bull. 4, U. S. Steel Corp.) a shot. Danger from CO in old workings can be readily de- tected by the use of canary birds (Fig. 102). Many explosions of dust or fire damp are due to the flame produced by explosives. Accordingly the so-called permissible explosive only should be employed. These do not produce a big flame. Miners should not tamp down charges of explosives with metal rods, due to the danger of premature explosions. Charges should be fired from a central switch after all men are checked out from the mine. Fire danger can largely be eliminated by the use of safety lamps and the protection of the shaft (Fig. 101). Addi- tional dangers encountered are from collisions between cars and lack of clearance between the cars and the wall, and also of electrocution from low overhead trolley wires. 16 242 PRACTICAL PREVENTIVE MEDICINE 14. Air Pressure. — Increased air pressure is only encountered by the "mud hogs" in caissons, in whom rapid decompression may produce the condition known as the "bends." This can be avoided by their gradual decompression in the air locks. (Fig. 103). 15. Fire hazards are numerous and varied. They are affected by the inflammability of the building or of raw mate- rials stored therein. Fire escapes should be adequate for the number of individuals in the building. In this connection we may call attention to the fact that the stair escapes permit more rapid escape from a building than the ladder type. They should preferably be built along a blank wall and connected to Ml " ~ Pig. 102. — The canary is to the mine rescue crew what a thermometer is to the physician. The bird is more susceptible to gas than human beings and when it topples from the perch in its little cage the rescue men know they have gas to reckon with. (G. H. Taylor: The Survey.) windows by platforms. Regular fire drills at unexpected moments will do much to permit an orderly exit when danger threatens. Lack of judgment in the location of the stair wells and elevator shafts frequently does much to spread a fire and prevent the escape of the inmates. If exit doors open outward their jamming by a panic stricken crowd will be largely pre- vented. Fire risk from inflammable or explosive gases will be much lowered by adequate ventilation. Automatic sprink- lers will usually keep blazes from spreading, and extinguish them in their incipiency. 16. Electrical Accidents. — Electric installations offer many opportunities for accidents of a serious character. Danger HAZARDS OF OCCUPATION 243 signs should be freely employed and dangerous parts of equip- ment should be painted red. Only experienced and competent Fig 103. — Air-lock on top of caisson. In sinking foundations for sky scrap- ing buildings men go down beneath the water level and work in compressed-air chambers or caissons. The air pressure is frequently more than three times the normal fifteen pounds per square inch. Workers, if released gradually during decompression in the air-lock avoid the "bends" or compressed-air illness. (Industrial Dis. Am. Labor Leg. Rev., 1912.) men should be allowed in rooms where dangerous apparatus or wires are installed, and no man should be left alone with a high tension current. Floors that are in dangerous proximity 244 PRACTICAL PREVENTIVE MEDICINE to wires at high tension should be covered with insulating mats. No repairs of mains or wires, or examinations or altera- tions should be permitted while they are under a high tension current. Switches should be provided with tell tale lamps, and when a switch is thrown open it should be tagged, and the switch kept open until the completion of the necessary work has been reported. Workmen should take the same precautions with dead apparatus that they do with live apparatus. Rubber gloves should be worn and the sleeves kept down. When working on the primary side of transformers, switchboards etc., only one hand should be used. Plenty of free room should be maintained about the switch boards and their backs should be enclosed. All motors, generators, transformers, etc., should be guarded and also provided with insulated platforms. Termi- nals, brushes and connections should be so situated that they will not be accidentally touched. 17. The most important factors in the production of indus- trial accidents are the following: (a) Carelessness. (b) Poor light. (c) Unsuitable clothing. (d) Cluttered up factories. (e) Lack of safeguards. (/) Fatigue, and I) Overcrowding of the workmen in the shop. CHAPTER XXVII OCCUPATIONAL INTOXICATIONS AND DISEASES Little definite data can be presented concerning the preva- lence of occupational diseases, since little attention has been paid them until recent years, and but four states require their reporting. Their frequency as well will be proportional to the prevailing type of economic development. The experience in Ohio will give us perhaps our best guide to their prevalence. Thus recently during a period of seventeen months, there were reported a total of 1204 cases of occupational diseases. The following were the most numerous: Benzene and benzol poisoning 33 cases Brass poisoning 124 cases Lead poisoning 544 cases Pneumonokoniosis 15 cases 1. Thus we see lead poisoning is by far the most important. Its importance is emphasized if we briefly survey the many occupations in which lead is handled and among whose workers lead poisoning may arise. This is presented in the following table, which represents the cases reported above. TABLE IX. — Industiues in which Lead Poisoning May Occur Industry Trade process No. of cases Painting and bronzing 4 Automobiles and parts Babbiting metals and solder Bicycles and sewing machines. . . . Brass and bronze products Carriages, wagons and parts Cars and repairs (R. R.) Carpentering on primed work, painting and sanding (Fig. 106) Melting 79 1 Painting and varnishing Founding and soldering Painting and sanding Painting, soldering, varnishing. . Painting and varnishing 2 3 42 3 Cars and repairs (not R. R.) 6 2 Chemicals Lead burning, ore crushing 6 '45 246 PRACTICAL PREVENTIVE MEDICINE TABLE IX. — {Continued) Industry Trade process No. of cases Coffins, vaults, etc. Copper, tin. etc Cutlery and tools. . . Electrical apparatus. Enameling and japanning Files Flags, regalia, etc Foundry and machine shop products Furniture and cabinets. Glass manufacture Scientific instruments Tin and sheet rolling mills Lead bar, pipes, sheets, etc Lead oxides and carbonates Oil refining Paint and varnish manufacture. . . Painting and varnishing (non mfg.) Porcelain enameled iron ware . . . Pottery Printing and publishing Rubber goods Safes and vaults Scales and balances Ship building. Signs and adv. novelties. . Smelting and refining. . . . Stereo and electroplating. Stoves and furnaces Wire (works and mills) . . . Miscellaneous Brass and lead founding, paint- ing, varnishing, buffing and soldering Machine shopping, soldering. . . . Tempering Lead burning, storage batteries, soldering Enameling File cutting and tempering Painting Die casting, founding, painting, soldering Painting and varnishing Lead putty working, mixing in- gredients Metal grinding, soldering Tinning Various processes Various processes Handling lead pipes Grinding, mixing, filing con- tainers, soldering, labelling. . . House painting Enameling Glazing processes, etc Linotyping (Fig. 104), type set- ting, etc Compounding, mixing, etc Painting and sanding Painting Soldering Painting Metal refining Casting Soldering , Galvanizing, painting, etc 13 3 7 107 3 3 36 25 4 61 5 43 6 7 1 1 4 1 3 3 From the foregoing it can be seen that the industries in which lead products are employed are varied, and that men engaged OCCUPATIONAL INTOXICATIONS AND DISEASES 247 in considerably different occupations may suffer from lead poisoning. Painters and those who sandpaper (Figs. 105, 106) painted work, workers in storage batteries, workers in rubber manufacture, printers (Fig. 104) and workers in lead products are the heaviest sufferers. The possibility of lead poisoning must always be borne in mind in the clinical examination of an industrial patient. 2. Channels by which Lead Gains Entrance into the Body. — In most manufacturing processes lead as a poison is encountered Fig. 104. — Showing installation of exhaust system for linotype machines. Each machine has a molten pot of type metal (lead alloy) from which lead fumes arise. (Bull. 209, Bur. Labor Stat.) in the form of dust, as well as in lead smelting and the manufac- tures of lead carbonate. Absorption by the lungs appears to be slight, the greater amount of dust gaining entrance by the alimentary canal. Most dust is caught in the nasopharynx and swallowed with the mucous secretions. The dust on enter- ing the stomach reacts with the hydrochloric acid and soluble chlorids are formed which are absorbed. When it reaches the blood it is believed to form a rather insoluble albuminate. If food is eaten at the same time less lead will be converted to 248 PRACTICAL PREVENTIVE MEDICINE Fig. 105. — Dry sandpapering. Dry sanding of paint is a frequent cause of lead poisoning. The operation fills the air with tiny particles of lead dust. {Industrial Dis., Am. Labor Legislation Review, 1912.) Fig. 106. — Wet sanding with pumice stone. Dust is avoided when sanding is done with wet pumice stone. (Industrial Dis., Am. Labor Legislation Review, 1912.) OCCUPATIONAL INTOXICATIONS AND DISEASES 249 the chlorid. Lead which is not changed to the chlorid passes out into the feces as the sulphid. Lead carbonate is more solu- ble in the gastric juices than the sulphate. In intoxication from lead fumes absorption is by the way of the lungs. It is a less common route than the alimentary, the principle occupations affected by this route being lead smelters and linotype operators. (Fig. 104). 3. Symptomatology of Lead Poisoning. — Females and young persons are predisposed to lead poisoning. The onset is very variable, usually manifesting itself in two to four weeks, rarely longer. The onset is more certain and the symptoms more severe when small doses are absorbed over long periods. A gradually developing pallor (anemia) with basophilic stippling of the red cells, a blue line on the gums close to the dental margin, colic and constipation with headache are usually observed. The patient may have convulsions, disturbances of vision or paralysis. Pregnant women always miscarry. 4. Remedies. — Efficient exhaust ventilation is essential for the removal of both dust and fumes. The amount of dust produced can frequently be reduced by slight alterations in methods. Provision should be made so that a little food can be kept in the stomach during working hours. Workmen should be instructed to expectorate saliva instead of swallowing it. Adequate washing facilities will assist in removing dust, as will also the requirement that the clothing be changed upon leaving work. In the painting trades much will be accom- plished by the substitution where possible of zinc paints for lead paints. 5. Arsenic. — Arsenic is chiefly encountered as a dust. Workers in the manufacture of Scheele's Green ( a pigment), wall paper, glazed colored paper, artificial flowers, the packing of white arsenic and at works where the ore is reduced, are affected. It acts as an irritant to the skin and mucous surfaces. (Fig. 107, 108). 6. Mercury. — A variety of different mercury salts and the metal itself may produce intoxication from the action of either dust or fumes. Thus we find that cinnibar roasters, workers in the extraction of gold and silver, the users of mercury air pumps, barometer or thermometer manufactures, water gilders and felt hat and fur dressers may become intoxicated. Its prevention chiefly requires improvement in ventilating facilities. 7. Benzin and Benzol. — These are chiefly used as solvents for quick drying paints and varnishes, for cements and blacking. 25° PRACTICAL PREVENTIVE MEDICINE Fig. 107. — Arsenic poisoning. Putting Paris green into a bolter. An old and dangerous method. (Industrial Dis, Am. Labor Leg. Rev., 1912) Fig. 108. — Arsenic poisoning. A comparatively dustless bolter. Respira- tors worn as an additional protection. (Industrial Dis., Am. Labor Leg. Rev., 1912.) OCCUPATIONAL INTOXICATIONS AND DISEASES 251 Fig. 109. — Room at boot and shoe factory. Women and girls are exposed to the fumes of naphtha from open bowls of cement. (Bull. 127, Bur. Labor Stat.) Fig. 1 10. — Casting yellow brass. When the molten metal is poured into the molds, fumes of zinc arise and are precipitated by the cool air of the room into fine gray powdered flakes. In the room shown these are unavoidably inhaled by the workmen, who are thus exposed to the disease known as brass founders' ague. (Bull. 127, Bur. Labor Stat.) 252 PRACTICAL PREVENTIVE MEDICINE Those exposed are chiefly cementers in the rubber and boot and shoe industries, as well as dry cleaners and painters. They produce faintness and stupor. Adequate ventilation is re- quired for prevention. (Fig. 109). 8. Zinc Poisoning f Brass Founders Ague). — Brass is an alloy of zinc and copper in varying proportions. When brass is melted a considerable volume of zinc oxide is given off as fumes. (See Fig. no). Thus brass moulders are chiefly exposed, though brass polishers suffer to a lesser extent. The attacks are acute and come on several hours after exposure. The workmen suffer from rigors followed by a fever, the whole lasting several hours. Chronically it may also produce asthmatic and bronchial symptoms. Efficient exhaust ventila- tion is required as a remedy. 9. Pneumonokoniosis. — Pneumonokoniosis is a chronic inter- stitial pneumonia accompanied by a deposit of pigment and usually due to dust encountered under conditions of employ- ment. The physical character of the dust is an important factor in the development of the condition. It affects workers in coal and stone, clay, iron, wool, flour, tobacco, iron oxide, ultramarine blue, hair, cotton, shell, leather and wool. Dust enters the lungs both by inhalation and the alimentary tract. Inhalation is probably the most important route. The inhaled particles pass to the alveoli despite the obstacles presented by the ciliated epithelium and the minute subdivi- sions of the bronchioles. They are ingested by the phagocytic epithelial cells which carry them to the connective tissue frame work of the lungs or to the lymphatics, and are later deposited in the bronchial glands. Those which settle in the mouth are enmeshed in the pharyngeal mucus and swallowed. Phagocytes carry them through the intestinal walls to the lymphatics, by which route they are carried to the lungs. An important related point is the fact that about seventy per cent, of these persons develop pulmonary tuberculosis, doubtless due to the irritation developed. Tuberculosis mortality is about four times as great among workers in dusty trades as in the population as a whole. The harder and sharper the dust the more likely is the condition to develop. It is relatively rare among workers in organic dust, in whom the dust usually sets up a chronic catarrhal condition which only rarely leads to structural changes. Various terms are used to designate this condition when produced by different dusts. Thus in: OCCUPATIONAL INTOXICATIONS AND DISEASES 253 (a) Coal miners (especially in hard coal) it is known as Anthracosis. (b) Quartz miners (gold) it is known as Silicosis. (c) Stone grinders it is known as Silicosis or Chalcicosis. (d) Pottery workers it is known as Aluminosis. (e) Iron or steel grinders it is known as Siderosis. if) Tobacco workers it is known as Tobaccosis and (g) Cotton workers it is known as Byssinosis. The degree to which it developes among workers exposed to hard dust is very high. Ganister disease is a form of silicosis. Fig. hi. — Grinding iron castings on emery wheels. The dust-removal sys- tem shown is effective and protects the workmen to a great extent from flying dust. (Bull. 127, Bur. Labor Stal.) The men are engaged in making the brick lining for smelters and retorts. Thus per one thousand men in the ganister trade, 42.3 miners, 179.8 grinders and 22.2 brickmakers die of silicosis. In the zinc mines of Joplin Mo. 66 per cent, of all miners have evidence of pulmonary disease. The available remedies are based upon dust removal and reduction. Thus exhaust ventilation should be employed where possible and the workmen required to use respirators. Wetting down of the abrasive work and wet processes should be used where ever possible. (Fig. in). 254 PRACTICAL PREVENTIVE MEDICINE REFERENCES Rosenau: Preventive Medicine and Hygiene. 3rd Ed., pp. 1035-1075. Kober and Hanson: Diseases of Occupation and Vocational Hygiene. Hayhurst: Industrial Health Hazards and Occupational Diseases in Ohio. Ohio State Board of Health. Van Schaack : Safeguards. The Aetna Life Insurance Company. List of Industrial Poisons. Bull. 100. Bureau of Labor. Department of Commerce and Labor. Dangers to Workers from Dust and Fumes and Methods of Protection Bull. 127, Bureau of Labor Statistics, Dept. of Labor. Various publications of the Bureau of Labor Statistics, Dept. of Labor; The Bureau of Mines, Dept. of the Interior; and The Bureau of Public Health Service, Treasury Dept. Lists can be secured upon request. SECTION IV CHAPTER XXVIII DISEASES ARISING FROM THE PUERPERAL STATE In the registration area of the United States, there occurred in 1916, 11,642 deaths during the puerperal state, equivalent to a rate per 100,000 of 16.3. These deaths are classified as follows: Accidents of pregnancy 985 Puerperal hemorrhage 1118 Other accidents of labor 1212 Puerperal septicemia 4786 Puerperal albuminuria and convulsions . . . .3087 Puerperal phlegmasia, alba dolens, embolus or sudden death . . 415 Following childbirth (not otherwise defined) ... 34 Puerperal diseases of the breast 5 During the period from 1901 to 1905 the annual average of the death rate from this group of causes was 14.2 per 100,000, in the next five year period it was 15.5 and during 1913, 15.8; 1914, 15.9; 1915, 15-2. In general it has shown an upward trend. Few classes of death seem more tragic or pitiful than these. We find here the young mother, looking forward with joy to the arrival of her first baby, or the mother of a family of several children," leaving orphans, broken homes, widowed fathers. Probably few deaths leave as great a load of sorrow as do these. It is interesting to compare the losses from these causes with those from some of the other preventable diseases; In 1916 typhoid fever caused 9,510 deaths; measles 7,946, and diphtheria 10,367. If these rates were calculated upon the basis of 100,000 women they would approximately be doubled, and be still higher if calculated in proportion to the women of childbearing age. A still more accurate idea may be secured from the number of maternal deaths per a given number of births. Data on this point can only be given for 1916 and for the birth registration area. The death rate per 1000 live births 255 256 PRACTICAL PREVENTIVE MEDICINE from all diseases caused by pregnancy and confinement is 6.5, from puerperal septicemia 2.9, and from all other causes 3.6 (Fig. 112). Of these deaths the most numerous are from puerperal sep- ticemia. This is important, for of the above causes puerperal septicemia is the least excusable as its preventable character was recognized prior to the bacteriologic era. Holmes first MATERNAL MORTALITY THERMOMETER AVERAGE DEATH RATE PER 100,000 POPULATION FROM CONDITIONS RELATED TO PREGNANCY AND CHILDBIRTH, 1900-1910 22_ SWITZERLAND BOGIUM' 1 - AUSTRAUA- JAPAN- JTCW ZEALAND- FTALY- N0RWAY- SWEDEN 3 — ^UNITED STATES SCOTLAND EN6LAND & W4LES PRUSSIA The United States lost over 16000 women in 1916 from childbirth. We have a higher maternal death rate than ary other of the principal countries except Spain or Switzerlancl CHILDREN'S BUREAU, U. S. DEPARTMENT OF LABOR. Pig. 112. — (Bur. Pub. 61.) pointed out in 1843 that this fever was similar to wound infec- tions and was chiefly due to the carrying of infectious material on the hands of attendants from one case to another. In 1847 Semmelweiss advanced similar ideas. Previous to this time the mortality from puerperal fever in maternity hospitals was appalling. Subsequent to the introduction of antiseptic treatment the mortality immediately fell until now in hospital practice maternal deaths are negligible as shown in the table: DISEASES ARISING FROM THE PUERPERAL STATE 257 TABLE X Year Hospital Place Confinements Deaths I9°7 1907 (14 years previous) 1907-8 Baudelocque Paris Basle Rotunda 1 Dublin 3,°34 6,000 2,060 I.O o.oS 3-o Yet despite the demonstration that the disease is unnecessary it is still with us and shows no apparent diminution. In hos- pital practice in the United States it is as rare as indicated by the foreign experiences, but among home confinements it is still apparently undiminished. While puerperal septicemia is undoubtedly the most clearly preventable disease of this group, yet a large proportion of the other deaths must be regarded as due to preventable causes. Nearly 80 years ago Holmes showed that childbed fever was transmitted from patient to patient by the hands of the atten- dants. It is undoubtedly true that obstetric asepsis is drilled into medical students the country over. Why then these deaths? A formidable proportion of confinements in some localities, a major proportion in others, are not attended by physicians but by mid wives. The degree to which the assist- ance of midwives is relied upon is largely proportional to the extent of the foreign born population. Thus during 1916 in the borough of Manhattan, 11,266 mothers were confined in hospitals and institutions and 47,384 in their homes. Of the latter, 19,524 or 41.4 per cent, were attended by midwives. These people regard the service of a physician at this time as an unnecessary expense. The majority of midwives have no special qualifications for their task in so far as training is con- cerned. Most can handle normal confinements but if complica- tions ensue, call in a physician. They have no idea of asepsis or antisepsis, make unnecessary and frequent vaginal examina- tions and introduce unsterilized instruments as well as unclean hands into the parturient canal. The knowledge they possess of obstetrics is extremely rudimentary and is largely acquired in a haphazard manner, never from competent instruction. Is it any wonder that puerperal sepsis is still with us? It probably will be a long time before the midwives disappear. If they are to be tolerated, the welfare of women demands that they acquire a reasonable competence in their profession. Some provision should be made for their formal instruction in 258 PRACTICAL PREVENTIVE MEDICINE obstetrics and none should be permitted to practice without a license from the state. Death certificates for women who die in the puerperal state should record the name of the attendant during the confinement and those who show a disregard for asepsis, as manifested by the development of cases of septice- mia, should be barred from practice. Physicians cannot ignore the fact themselves that the instruc- tion that medical students receive in obstetrics and obstetrical asepsis is inadequate. We cannot belabor the mid-wife and gloss over the defects in our own practice and teaching. The women themselves need instruction in the necessity for good care at the time of confinement and prior thereto. Husbands must learn that money spent to safeguard the life of their wives and children at this critical time is spent wisely and for a stern necessity. Such service is worth a respectable fee, a consideration which prevents many from employing the services of a competent physician and nurse. Their meager circumstances only permit them to secure the uncertain assist- ance of a mid-wife. This is largely a problem of urban popula- tions. The best solution appears to be through the agency of prenatal and maternity clinics. Prenatal and maternity clinics are designed for the welfare of both the mother and child who without assistance would not receive adequate care prior to, during, or subsequent to con- finement. They are of equal value in the elimination of infant mortality. They are variously maintained, either by hospitals, philanthropic organizations or health authorities. By educa- tional propaganda efforts should be made to inform women of the assistance available and they must be encouraged to present themselves to the clinic some time prior to confinement for careful examination. If serious conditions are found arrange- ments for continuous observation and care must be made. In any event the prospective mother receives instructions in the proper physical care of herself and in making suitable arrange- ments for her anticipated child. Satisfactory results from attendance during the prenatal period are only secured where arrangements permit judicious home visiting to ascertain that the advice given has been understood and is being acted upon. Advice upon diet, clothing, exercise and care of the breasts is especially needed. At the time of confinement arrangements are made for the medical care of the mother if she is unable to provide for it herself, or if the presence of complications necessi- tates hospital care, to provide admission to the maternity wards. The prenatal work of the clinics very largely relates to the DISEASES ARISING FROM THE PUERPERAL STATE 259 proper care of the infant, and as such will be considered under infant hygiene. Co-ordinated cooperation with other chari- table agencies is frequently necessary to enable an indigent mother to receive proper food. Another group of women in entirely different circumstances usually fail to receive adequate care at this period. Usually the difficulty is not a question of good or bad obstetric care or inability to provide for a physicians services, but rather the inaccessibility of any assistance at all during this time. This is the condition which many women in rural districts must face, particularly in the extreme north and west where pioneer conditions prevail. Many children are born with no other attendant than the husband, a relative or neighbor. The nearest physician may be located many miles away and a hospital many miles further. With inadequate roads and means of communication it is not possible to notify the physician in time. Under these circumstances the cost of a physicians services may seem unnecessarily great and is frequently fore- gone. The problem of these women is difficult, but a solution seems available. It probably can satisfactorily be accom- plished along these lines; (a) The establishment of a rural nursing service centering at the county seat, with nurses especially trained to discern the danger signs of pregnancy. (b) An accessable county center for maternal and infant welfare at which mothers may obtain simple information as to the proper care of themselves during pregnancy as well as of their babies. (c) A county hospital with provision for maternity cases, for the proper care of abnormal cases and of normal cases when it is convenient for the women to leave their homes for confinement. (d) Skilled attendants at confinement available to each woman. REFERENCES O. W. Holmes: Puerperal Fever, The Contagiousness of, Reprinted in Carmac's " Epoch Making Contributions to Medicine," pp. 399. Maternal Mortality from all conditions connected with Childbirth in the United States and Certain Other Countries. Bull. 6, Misc. series, Children's Bureau, Dept. of Labor. Maternity Care and the Welfare of Young Children in a Homesteading County in Montana. Rural Child Welfare Series, Bull. 3, Children's Bureau, Dept. of Labor. The Supervision of Midwives in New York City. Mo. Bull. Dept. of Health, pp. 117, May, 1919. SECTION V CHAPTER XXIX DISEASES TRANSMITTED FROM PARENT TO OFFSPRING Two dissimilar groups of diseases are here considered. The first includes those diseases due to infective agents in which it is possible for an invasion of the germ cells, or intrauterine infection of the foetus, to occur. Such is known to be possible in the care of syphilis, tuberculosis and small-pox. However with all of these such means of transmission is unusual, and is not the means by which the infection is perpetuated in the population as a whole. Such transmission is of greater im- portance in syphilitic disease than in the other two, either by reason of a fatal outcome to the fetus, or a permanent injury to those which do happen to be born at term. These infections from a public health standpoint have however, already been adequately considered. The second group comprises the true examples of hereditary transmission from parent to offspring. By heredity we mean the transmission from parent to offspring through the germ cells of properties inherent or characteristics of the parent or of the parental stock. By disease in this connection we have reference to any departure from the normal, regarding the normal not as any fixed point, but as the limits between which any particular characteristics of the majority of individuals will fall. The hereditary diseases in the strict sense may be divided into groups depending upon whether or not their transmission conforms with the Mendelian principles. We shall first con- sider those which conform to these laws. DISEASES TRANSMITTED ACCORDING TO THE MENDELIAN INHERI- TANCE Before considering these diseases it may be well to briefly review the more salient principles of mendelian inheritance. 260 DISEASES TRANSMITTED FROM PARENT TO OFFSPRING 26 1 Its principles have been found to hold true for all forms of life and we can perhaps illustrate it most conveniently by reference to the vegetable kingdom. If the pollen of red flowered peas (male) is employed in fertilizing the ovaries (female) of a white flowered pea, the mature plants which develop from the seeds of this fertiliza- tion (hybrids) are all red flowering like their male parent. The red flowering characteristic is stronger in leaving its influence upon its offspring than the white flowering charac- teristic of the mother. The red characteristic is therefore said to be dominant and the white character recessive. The recessive character is not lost in the first generation of hybrids, but is only latent, as we shall find when those hybrids are crossed with each other. The offspring of those hybrids when brought to flower will not all be found similar to their parents, but will be arranged in groups according to very definite rules. In the first place three fourths of their number will be red flow- ered, i.e., present the dominant characteristic, while one- fourth will be white flowered, that is, present the recessive character. The two groups are in a ratio of 3 : 1, sometimes called the Mendelian ratio. If now then like individuals of the third generation be crossed with each other, it will be found that among the progeny of the white flowers, only white flowered offsprings will occur in the fourth generation. On the other hand, of the progeny of the red flowers, one fourth will be as red as the original male parent, while one half will be less clearly red and show clearly that they are hybrids, and one-fourth will be white. Thus of the fourth generation, one-fourth will present only the dominant characteristic, one- fourth the recessive character and the remaining half, though appearing like the dominant, possess the properties of hybrids. (Fig. 113). One may designate by the term determiner the unknown substance in the germ cells which determines in some way the different characteristics of an individual, such as the color of the skin, the kind of hair, mental traits, etc. If each of two parents possess a given character and each one transmits the determiner for that character to their offspring, then the offspring will possess two determiners for a given character, one from each parent. Then, unless there is some- thing to prevent it, this offspring will in turn transmit two determiners to its progeny. If the other parent of this genera- tion also contributes two determiners the third generation 262 PRACTICAL PREVENTIVE MEDICINE will possess four determiners for each character and so the num- bers of determiners would multiply. This however is prevented by the division of the chromosomes in the germ cell before maturity is reached, in which it is assumed the determiners reside. Thus only one half of the determiners pass into each vM "4, RR=. DR= t dd4 »*-3 ( r r J rr r DR J DP nv&Rj OR i ^ D j D D ■ and so on amond the hybrids 1 H n i? One half normal All normal R=Recesstve trait P=Dominant" trait 5Rl| Duplex, pure pfc Simplex., Hybrid Fig. 113. — Mendelian inheritance. mature germ cell and there is actually no increase. Therefore in the union of hybrid germ cells each containing one deter- miner for a given character, the determiners unite and depend- ing upon whether they are similar or dissimilar, dominant or recessive, the offspring will according to our example, be either like the dominant male plant, the recessive female plant, or DISEASES TRANSMITTED FROM PARENT TO OFFSPRING 263 the hybrids, which possess both the dominant and recessive determiners alone. The former we can designate as a duplex, the latter (the hybrids) as simplex combinations of deter- miners. Now when an individual who appears normal but has the dominant determiner in duplex is united with a hybrid, two kinds of offspring may result. One half will have the dominant character in simplex and one half in duplex but all will appear as normal. On the other hand if an individual with a recessive determiner in duplex, is united with a hybrid with one dominant and one recessive determiner, two kinds of offspring are likewise possible. One half will have one domi- nant and one recessive character each (simplex) but appear like the normal who has the dominant character in duplex and one half will have the recessive character in duplex and will not appear true to the normal type. (Fig. 113). Certain diseases appear to be transmitted from parent to offspring by either dominant or recessive characteristics of the germ plasm. Their characteristics are briefly presented. (a) Huntington's chorea is a condition in which there are marked involuntary, irregular contractions of the muscles leading to a more or less constant movement of the limbs. There is also dementia. It begins in middle life, affects both sexes about equally and is usually transmitted whenever present in either parent. It is therefore a dominant trait. Many of the cases in this country are traceable to several families belonging to an old New England colony. (b) Albinism refers to a condition in which there is an absence of pigment from the skin, hair and eyes, a condition seen in white mice or rabbits. It is rare in man. It is undesirable since the lack of pigment makes the skin and eyes very sensitive to light. It is a typically recessive condition. (c) Deaf-Mutism refers to a kind of deafness which begins early in life before the power of speech has been acquired, hence these individuals can neither hear nor speak. Fay has exten- sively studied this inheritance. Of 335 matings of congenitally deaf parents, 25 per cent, yielded deaf offspring. A total of 779 children were born of whom 26 per cent, were deaf. That all children of such marriages are not deaf is doubtless due to the fact that the parents are not deaf in the same way and one parent brings into the combination something which the other lacks. (d) Insanity may result from various causes. Some cases are the result of organic brain disease. Such are not inheritable. 264 PRACTICAL PREVENTIVE MEDICINE On the other hand with functional insanity without well defined lesions, some evidence of heredity is available. It is the tendency to insanity or the neuropathic trait which is inherited. It follows the laws of heredity governing recessive characters. (e) Feeble Mindedness like insanity in many instances is a recessive trait. It is not always easy to determine who is and who is not a feeble minded individual. At one end of the scale we have those who are exceptionally able. In a general way we may say that a child is feeble minded who for no obvious reason at the age of ten is no further advanced in his school work than are other children at the age of six or seven. Within normal variations we may have children one or two years behind or in advance of the average. Mendel's law is also exemplified by what are known as sex- limited diseases, examples of which are color blindness and hemophilia. These are diseases that appear almost only in the male line, but are transmitted only through the female line. Thus if a given man be affected, his sons will not have the disease nor will they transmit it to their offspring, nor will his daughters have the disease, but they will transmit it to their sons. The explanation of this is associated with the deter- miner from the male chromosome. Striking examples of this type of heredity are observed with multiple sclerosis, atrophy of the optic nerve, color blindness, myopia, ichthyosis, muscular atrophy and hemophilia. DISEASES NOT CONFORMING TO MENDEL'S LAW (a) Friedreich's ataxia begins in childhood and usually occurs in a family having other members similarly affected There are curious forms of incoordination, loss of knee-jerk, early talipes equinus, scoliosis/ nystagmus and scanning speech. Since it has usually been observed as a family disease it is assumed to be transmitted hereditarily. (b) Reversionary inheritance does not appear to follow the Mendelian laws. It represents a return of the offspring to a lower type, a development which is incomplete and corresponds to a stage characteristic of an earlier period in the development of the species, whether affecting the body as a whole, or only some particular portion, such as the nervous system. The typical degenerate is of poor bodily development, the brain is smaller than normal, with convolutions less abundant and less fully formed, possesses a degraded physiognomy, little capacity DISEASES TRANSMITTED FROM PARENT TO OFFSPRING 265 for sustained attention or prolonged thought, is cunning rather than intelligent, is deficient in a moral sense; in all these characteristics resembling the lower, less developed types of our own species. Thus this type of inheritance is the reasser- tion of properties which have remained latent. NATURAL IMMUNITY Immunity is either natural or acquired. The former is inherited through successive generations in a species or race. Acquired immunity does not appear to be a transmissible characteristic, at least to such an extent that changes are rapidly observable in the span of a few generations. EUGENICS Eugenics is the science of the improvement of the human race by better breeding. The success of a marriage from the standpoint of eugenics is measured by the number of normal, cultivable offspring that arise. It has to deal with traits that reside in the germ plasm. The superstition of pre-natal in- fluence and the effects of venereal disease lie outside the scope of eugenics. In the foregoing paragraphs we have only sketched the hereditary transmission of certain undesirable qualities. If space permitted, a similar sketch of the hereditary transmission of desirable qualities could be presented. It is these eugenics desires to augment and to eliminate the undesirable. The science is in its infancy at present and our knowledge is but fragmentary. Some progress can be made among those of intelligence by propaganda explaining the known facts. Un- fortunately among those possessing many undesirable charac- teristics such means of propaganda is impossible. Appeals cannot be made to the degenerate, to the criminal, to the feeble minded. The elimination of the hereditary traits of this char- acter require the united action of society to stop the procreation of those who are unfit by reason of defective germ plasm. No real progress has been made in this direction but in some places a creditable start has been made. Prohibition of the marriage of those possessing socially undesirable characteristics will not prevent the illegitimate procreation of such individuals. Such laws are manifestly inadequate. A solution that has been legally adopted in some 266 PRACTICAL PREVENTIVE MEDICINE states is that of sterilization, but its enforcement has been limited. There is no question but that such a procedure applied to all the feeble minded, the epileptic, insane or criminal persons in the country would produce an enormous reduction in the institutional population in the course of a generation. The greatest difficulty lies in the satisfactory definition or accurate recognition of those whose procreative abilities should be sacri- ficed to the social welfare. An alternative solutionis the segre- gation in institutions of such persons until the reproductive period has passed. We could expect the same results. On the other hand, there is the group composed of those having defects not inimical to society. Some of those traits may involve the possession of severe handicaps, and it is per- haps better that such traits should become extinct. More satisfactory results in this direction can perhaps be accom- plished through the persuasive powers of the family physician in whom the afflicted individual has confidence. The necessity or desirability for celibacy can be judged from the type of undesirable trait presented and a knowledge of the type of Mendelian inheritance followed. REFERENCES Davenport: Heredity in Relation to Eugenics. Rosenau: Preventive Medicine and Hygiene, 3rd. ed. pp. 470-515. Mental Hygiene, Reprint 164, Public Health Reports. Overton and Denno. "The Health Officer." Chapter XXX. SECTION VI SPECIAL ASPECTS OF HYGIENE AND SANITATION CHAPTER XXX HYGIENE OF INFANCY The age period of infancy includes all those under the age of one year. This undoubtedly is the most critical period of life, during which the newly born is adapting itself to a new en- vironment. It is not surprising that many have a great deal of difficulty in meeting the changed conditions encountered after birth and die. The deaths during the first year of life are higher than at any subsequent age period (Fig. 113a). In 1 9 10 they amounted to 20 per cent, of all the deaths in the registration area. Ten per cent, of all deaths during the first year occur in the first day of life and 25 per cent, during the first month. Roughly 8 per cent, of infants born die during the first month of life. The proportion of all born which die during the first year of life varies from 10 to 35 per cent. From birth there is a steady decline in the mortality throughout the first year and when the second year is reached the mortality is only one-fifth of what it was in the preceding year. In recent years the deaths during this age period have been steadily falling. One or two hundred years ago they were simply appalling, even in the highest society. The appalling character of this mortality is heavily emphasized when we consider that a larger proportion, probably the majority of these deaths are preventable (Fig. 114). THE CAUSES OF INFANT MORTALITY MAY BE ROUGHLY PLACED IN SIX GROUPS The first of these includes the deaths due to prematurity, congenital defects and debility, and to accidents at birth. They are responsible for about 25 per cent, of the deaths. These are 267 268 PRACTICAL PREVENTIVE MEDICINE largely due to parental influences, to diseases of the parents, such as syphilis and gonorrhea, alcoholism, overwork of the mother during the latter portion of the pregnancy, eclampsia, pelvic deformities and the maladministrations of incompetent mid-wives. Many of these are associated with the death of the mother. While the majority of the deaths in this group are not directly due to preventable causes, yet a considerable por- INFANT MORTALITY THERMOMETER DEATHS UNDER 1 YEAR OF AGE PER 1,000 BIRTHS HUNSARY- CHILE- GEMUN EMPIRE- JAPAN SERBIA ITALY- FRANCE- ™ys SWEDE N NORWAY NEW ZEALAND — ^ (7^ 300- 2Z£ 25SE 22£. 3£z E5r )C0 Z —BULGARIA IGIUM UNITED STATES Within the first year after birth, the United States loses linlO of all babies born. It ranks eleventh among the principal countries of the world. New Zealand loses fewer babies than an/ other country Rates are for latest available years up to 1916. "^ CHILDREN'S BUREAU, U. S. DEPARTMENT OF LABOR. Pig. 113, a. — (Bur. Pub. 61.) tion must be regarded as due to causes which are indirectly preventable. The second group comprises the nutritional disturbances and the acute gastro-intestinal diseases. These are responsible for about 35 per cent, of the mortality. These must be regarded as primarily due to bad feeding. This fact is emphasized by rinding that 85 per cent, of infantile deaths are among the bottle fed and further that 90 per cent, of the deaths from HYGIENE OF INFANCY 269 diarrheal diseases are among those fed from the bottle. Bad feeding of infants is largely a question of artificial feeding, so as a consequence we must regard all deaths in this group as preventable. Closely associated with bad feeding is the in- fluence of hot summer temperatures, which not only exercises a directly injurious influence on the baby, but also on the keeping qualities of his food. The third group includes the acute respiratory infections, bronchitis, bronchopneumonia and lobar pneumonia. These (B» ess 1900 1905 190 £00 ISO 66 rn a/ £ ml v'r ISO fr an ce 170 160 -« p j •^ i v nY V .. 150 ' \\ 1 4 >\ , ~- ' \ R: fi \ •40 V 1 >. \i 1 s\ ** ^ 1^ !30 D a? na rA — — \ \ ,- . \ 120 \ 1 no \ s / \ too \ & iVt 'd. m &O A 0/f >3 Ws 'cu **■ eo 70 ftl Fig. 114. — Infantile mortality (deaths of infants under 1 year of age per IOOO births per annum exclusive of stillbirths). German Empire, France, England and Wales, Denmark, Sweden, and New Zealand — 1892 to ioir. (Trask: Suppl. 12. P. H. Rep.) produce about 20 per cent, of the deaths. They largely arise as a result of overcrowding or bad ventilation. The fourth group includes the acute infectious diseases. These at this age period are of lesser importance, causing only about 3 per cent, of the deaths. Whooping cough is the prin- cipal member of this group as far as infants are concerned. Fifty-seven per cent, of the deaths from whooping cough occur during the first year and 23 per cent, during the second year. An infant is susceptible from birth to whooping cough. To- 270 PRACTICAL PREVENTIVE MEDICINE ward many of the other acute infections an infant presents a considerable immunity which persists for several months. Tuberculosis, chiefly meningeal in type, causes about 2 per cent, of the deaths. Infants should not come in contact with adults having open lesions of tuberculosis, nor be fed upon the milk of tuberculous cows. Syphilis causes only about 1 per cent, of the deaths. It operates chiefly as a cause of prematurity and miscarriages. Nearly everywhere infant mortality is greatest in the most unsanitary and crowded areas. As a consequence the extent of infant mortality is a good index of sanitary conditions. THE INSTITUTIONAL CARE OF INFANTS The infant that is doomed to institutional care has very poor prospects in life. The majority are illegitimates and hence are unwelcome. While the mortality in institutions is high even with the best of care and the employment of wet nurses, while without wet nurses it may reach 100 per cent. The following factors are principally responsible for this appalling mortality: (1) The institutions are usually over- crowded, so that respiratory infections run like wild fire; (2) There is a lack of sufficient fresh air ; (3) Respiratory infections, whose dissemination is favored by overcrowding and defective ventilation, and lastly, (4) The lack of mothering. Babies thrive best, other things being equal, where they receive a great deal of individual, personal attention. They seem to require encouragement and coaxing over the period of their adaption to extra-uterine life. The following conditions will largely reduce the mortality among this class of infants. Every effort should be made to induce the mother to keep her child. Its chances of survival are enormously improved, even though it is later placed in an institution. Institutions for the care of infants are usually privately conducted and commonly known as "Baby Farms" or boarding houses. These should be placed under the control and supervision of health authorities, so that abuses in their conduct may be eliminated. For this purpose their licensure is necessary. A practice that is preferable to the employment of boarding houses is that of boarding the babies in private families with wet nursing. This enables the infant to receive the necessary individual attention. Infant hospitals should be only for those acutely sick and should not partake of the HYGIENE OF INFANCY 27 1 character of boarding houses. As soon as possible the child should be returned home. Every hospital which cares for infants should be provided with wet nurses. Wassermann. tests should be made on both infant and nurse to prevent the transfer of luetic virus in either direction. BREAST FEEDING Breast feeding is essential to the really proper welfare of an infant. Its value is seen from the fact that breast fed infants seldom suffer from intestinal troubles. The extent to which breast feeding is practiced varies in different countries, districts of cities and with different races and customs. Thus in 191 1 in Boston, only 68 per cent, of the infants were breast fed. It is possible to increase this proportion. Various causes, some justifiable, are responsible for the failure of some mothers to breast feed their offspring. Some are deliberately unwilling and regard it as an annoyance, while others do not appreciate its importance from the standpoint of their child's welfare. Others have to work away from home under conditions that do not permit them to take their child. Some are physically unable to nurse because of lack of milk. The glittering ad- vertisements of proprietary foods lead others astray. These obstacles can largely be overcome. Pregnant and nursing women must be educated in the importance of breast feeding. Certain classes of mothers, especially those whose children most require assistance, can be reached through pre- natal clinics and child welfare conferences. Employers of married women should make provision for mothers to bring their babies to work. Indigent mothers who are unable to secure sufficient food for themselves, let alone a baby in addi- tion, require charitable assistance. ARTIFICIAL FEEDING If artificial feeding is properly carried out most babies will thrive upon it. The difficulty lies in the fact that it is fre- quently, if not usually, improperly carried out. Difncuties arise from the fact that a poor grade of cows milk may be the only milk available, improper modifications may be employed, the milk may be inadequately kept or is spoiled and the bottles and nipples may be neglected. Proper artificial feeding requires the following conditions. 272 PRACTICAL PREVENTIVE MEDICINE An adequate supply of either pure raw cows milk of certified grade or pasteurized milk must be available. Charitable organizations should make provisions either for its free distri- bution or its distribution at a reduced price to indigent mothers. Similarly ice supplies for its proper keeping in the home should also be available. In the absence of regular refrigerators, sim- ple devices can be employed for the refrigeration of the milk. Attention has been called to these in the section on milk. Mothers should be instructed in the proper care of the milk and of nursing bottles. Proper modification of the milk is essen- tial. Many physicians are not familiar with proper procedures for the adaption of cows milk to infant feeding. Proper education of physicians in these procedures in order that they may in turn properly instruct their patrons is necessary. Parents may also be instructed in milk modification at pre- natal clinics and child welfare centers. CHARITIES AND CLINICS We have already called attention to the value of prenatal clinics in the education of expectant mothers. These organiza- FiG. 115. — Everything prepared for a demonstration of baby care (Stamford, Conn.). Such demonstrations are of great value in educating mothers in infant care. (Children's Bureau Pub. 15.) tions are scarcely of less benefit in the education and supervis- ion of mothers after the birth of the baby than they were before HYGIENE OF INFANCY 273 the event. Advice and assistance on all subjects relating to the child's welfare is given. Child welfare centers offer similar assistance and instruction (Fig. 115). Many notable milk charities have been organized. These provide satisfactory modified milk at a cheap price or free of charge. Of inestimable value in the education of mothers and in the reduction of infant mortality are the services of visiting nurses. These women serve either under the auspices of some local philanthropic organization or the local health authorities. Their principal work is in the infant's home. It is in this con- nection that the prompt registration of births is of great value in the control of infant mortality. These nurses visit all homes from which births are reported within a week or ten days. They ascertain if the mother needs advice or assistance. This if required is given, or if financial assistance is necessary they direct the mother to the proper source of the needed help. Regular follow up visits are made to see if the mother is properly carrying out the advice. Women for successful work in this field must possess a great deal of tact and diplomacy. The results of this work are exceedingly beneficial. HEAT The extreme heat of the summer months makes this period very trying for infants. This is especially true where the effects of the heat are exaggerated by overcrowding, by reflected and absorbed heat from buildings and pavings, and where ventilation is inadequate. It exercises a directly depressing effect on a child's vitality. The heat also prompts the growth of putrefactive bacteria in the child's milk, which tends to increase the frequency of digestive disturbances. An abun- dance of flies and the absence of fly protection assist in the spread of diarrhea and dysentery. Great care should be given the child's food, it should be kept as cool as possible and pro- tected from flies. Furthermore many mothers constantly overclothe their babies during the summer. INFECTIONS We may call attention again to several communicable diseases of especial importance to infants. First, the severity of whooping-cough. Second, that ophthalmia neonatorum which 274 PRACTICAL PREVENTIVE MEDICINE causes about one-fourth of all blindness, can be effectively avoided by the employment of Crede's method of prevention with silver nitrate. And lastly small-pox vaccination is best given for the first time in the first year before the second sum- mer. It may be safely given when the child is one month old with less discomfort than an adult experiences. REFERENCES Birth Registration: an aid in protecting the lives and rights of children. Monograph i, Children's Bureau, Dept. of Labor. Handbook of Federal Statistics of Children. Pub. 5, Children's Bureau. Dept. of Labor. A Tabular Statement of Infant -Welfare Work by Public and Private Agen- cies in the United States. Pub. 16, Children's Bureau, Dept. of Labor. Infant Care. Pub. 8, Children's Bureau, Dept. of Labor. Child's Welfare Exhibits. Pub. 14, Children's Bureau, Dept. of Labor. Baby-week Campaigns. Pub. 15, Children's Bureau, Dept. of Labor. Baby Saving Campaigns. Pub. 3, Children's Bureau, Dept. of Labor. Summer Care of Infants. Supplement 16, Public Health Reports. Heat and Infant Mortality. Reprint 155, Public Health Reports. Also various studies of infant mortality in Waterbury, Conn., Johnstown, Pa., Manchester, N. H., Montclair, N. J., and Brockton. Mass., published separately by the Children's Bureau. CHAPTER XXXI HYGIENE OF CHILDHOOD By the term childhood we refer to the age period from infancy to puberty. As measured by the death rate, this is the most hardy period of life, being less than at any other age period. The hygienic development of the child during this period is indirectly of great importance as it will profoundly influence the physical welfare of the individual as an adolescent and adult. We will briefly consider the more salient of the hygienic hazards which confront the child: COMMUNICABLE DISEASES During the months immediately following birth there is a temporary immunity toward measles, scarlet fever and diph- theria. This disappears during infancy, so that by the time childhood is reached the individual is susceptible to nearly all of the acute infections. Thus we find that certain diseases have their greatest age incidence at this period of life, namely, measles, german measles, mumps, chicken pox, diphtheria, scarlet fever, poliomyelitis, meningococcic meningitis, etc. This peculiar maximum may perhaps be due to either or both of the following factors, namely (i) to the susceptibility of the children, or (2) to the greater opportunities which exist among children for the transfer of infective secretions by the agencies of contact. On the other hand, infection with Mycobacterium tuberculosis, whose presence is most commonly manifested by clinical tuberculosis during adolescence and early adult life, is received during childhood. ORTHOPEDIC DEFECTS These are deformities arising from faulty posture, and the types we shall consider are functional in character. They chiefly arise as a result of prolonged periods of seating, such as a child is forced to maintain at school. (a) The most common of these is the so-called "Round Back." It is manifested by a prominent abdomen, a back- 275 276 PRACTICAL PREVENTIVE MEDICINE ward convexity of the spine, a contracted chest and a ptosis of the viscera. The foot is usually everted outwards. It gives the individual the appearance of leaning backwards. Its contributing causes include poor nutrition, hard physical work and poor postures. Its development is assisted by poor cloth- ing such as the continuous drag which elastic garters exert when suspended from the shoulders. It may be remedied by properly suspended clothing, by proper seats and the inaugura- tion of relaxation periods which include setting up exercises. (b) The second group includes the functional lateral devia- tions or scoliosis. All functional scolioses are single curva- tures of the spine. The most common type is where the con- vexity of the spine is to the left. These produce an elevation of the right crest of the ileum, a waist line indented more on the concavity (right side) of the curve, the opposite (left) shoulder is higher and rotated forward, the right (concave) side is seen to be higher or more prominent. With deviation to the right, which includes only about 10 per cent, of the cases, the above conditions are reversed. All of the above conditions must be observed for a diagnosis. It is correctable by proper gymnastic exercises, but if uncorrected may lead to structural changes. OCULAR HYGIENE The ocular conditions of greatest importance during child- hood include the acute infections and eye strain. Among the former, various forms of acute conjunctivitis and trachoma are of importance. School and household epidemics of these are not unusual, due to the exchange of infective secretions by contact. While acute conjunctivitis may lead to a permanent impairment of vision, trachoma is of far greater importance and less easy to control. Eyestrain or defective vision may be due to either hypertropia or myopia, astigmatism or muscular insufficiency and strabis- mus. These should be properly corrected by refraction measures or surgical procedures. When uncorrected they hinder a child's progress inasmuch as it is impossible for him to follow the work of his class intelligently. AURAL HYGIENE The conditions of the ear of greatest importance are discharg- ing ears and defective hearing. Discharging ears should receive suitable medical treatment, while those having defective hearing should receive preferential seating in class rooms. HYGIENE OF CHILDHOOD 277 HYGIENE OF THE NOSE AND THROAT A remarkable and close correlation exists between the condi- tion of a child's nose and throat and the degree of intelligence it manifests. The reasons for this correlation are not apparent. One would expect to find such a correlation to exist with hearing and vision but such is not the case in our experience. The conditions of greatest importance and most common occurrence are sore throat, hypertrophied tonsils, adenoids and nasal ob- structions. These require suitable medical or surgical treat- ment for alleviation. DENTAL HYGIENE Faulty conditions of the nose and throat may profoundly influence the dentition. Thus adenoids will interfere with the development of the jaw and produce irregularities of the teeth. Decay or caries of both the first and second dentition is com- mon and very important. The fermentation of carbohydrate materials in food particles lodged between the teeth results in the production of lactic acid, which is a solvent for dentine and enamel. Soft carbohydrate foods rather than hard tend to lodge in these situations. Their lodgment is favored by the buccal mucous. The vigorous mastication of hard carbohy- drate foods will overcome a great deal of this difficulty. Pyorrhea is an important dental defect whose cause and prevention is unknown. Pus pockets about the roots of decaying teeth are of greater importance than their small size and localization would at first indicate. They are one of the most common seats of focal infection and a situation from which infective emboli gain access to the circulation and produce disorders elsewhere. Their recognition and elimination is of great importance. It is advisable to make inexpensive repairs to the early teeth, as their premature disappearance may unfavorably affect the second dentition. The use of the tooth brush should be made a regular habit. NUTRITIONAL DEFICIENCIES Children whose state of nutrition is subnormal show a dis- tinct lack of subcutaneous fat, they are under weight, thin, pale and have pinched faces. The condition may be due to a lack of good food, or to insufficient or improper food, to indiges- 78 PRACTICAL PREVENTIVE MEDICINE tion or improper mastication. Or it may also be due to a lack of fresh air associated with overcrowding, a lack of rest or overwork, tuberculosis or diseases of the liver and kidney. Each of these possibilities will demand investigation and special treatment if detected. Where due to insufficient m or improper food the economic status of the parents is usually the important factor. Some means of charitable relief is temporarily required. One solution employed is to provide simple lunches at a low price at school. SCHOOL SANITATION This question is important, inasmuch as the schools concern all children. Furthermore the close association between susceptible children at school makes the school an important Pig. 116. — School with insufficient windows. The windows are not large enough to provide sufficient light. They should be more numerous and the window panes larger. (Public Health Reports, Sept. n, 1914.) clearing house for communicable diseases. The many import- ant features in school sanitation can only be lightly touched. (a) Lighting. — A general and safe rule is that lighting space should be provided in each room in the proportion of one square HYGIENE OF CHILDHOOD 279 foot of window space for each five feet of floor space. In locating the seats it is important that the lighting come from the left and that none be permitted to shine directly into the eyes when the individual is properly located in his seat (Fig. 116, 118). (b) Heating and Ventilation. — The maintenance of the proper mental and physical efficiency in the children requires that the teachers maintain proper conditions of temperature Pig. 117. — A dangerous school privy. Cover to seat of privy and door to entrance are lacking, thus allowing access to flies and animals. Excreta are deposited upon the ground, thus bringing about soil pollution. Thirty-eight out of forty children in this school were found to be infected with hookworm. The percentage of hookworm infection in the county in which this school is located was 82.6. (Public Health Reports, Sept. 11, 1914.) and humidity in the class rooms. This can be accomplished by careful supervision, but is frequently ignored. (c) Blackboards selected for recitation or demonstration purposes should be so situated that no light is reflected from their surface into the eyes of the pupils. These should have a dull black surface. (d) A hygienically satisfactory supply of individual drinking 280 PRACTICAL PREVENTIVE MEDICINE cups should be available or drinking fountains should be used. Common drinking cups should not be tolerated. (e) Adequate toilet facilities with separate toilets for the sexes are necessary. These should be maintained in a state of proper cleanliness and working order. Washing facilities and indi- vidual towels are also necessary. Teachers should require their use by children who come to school with dirty faces and hands (Fig. 117). (/) Proper seating of the children with regard to their stature and the seats available is necessary. This is important from the standpoint of orthopedic development. Pig. 118. — Front of classroom, Cross Roads school. Note the relation of the seating and black boards to the illumination. (Bureau Education, Bull. 12, 1914, Plate 22.) (g) The method employed for cleaning class rooms should avoid unnecessary dust production and should preferably be done at the close of the school day. Common books and pencils tend to favor the distribution of infective agents and are undesirable. (h) Provision should be made for one or more periods of physical relaxation during the school day. These may be devoted to drills, games, deep breathing exercises or a recess. In the arrangement of the curriculum the analytical courses should receive first place, so that they are taken while the mind is fresh. HYGIENE OF CHILDHOOD 28l SCHOOL INSPECTION The medical inspection of school children is variously under either the Board of Education or the Board of Health, or in some places is accomplished jointly. As a method it was especially introduced for the purpose of controlling communi- cable diseases by the regular and frequent inspection of the children to detect mild cases, carriers and convalescents, and to secure their exclusion from school until no longer infective. The results secured in this direction are very satisfactory. It permits the rapid checking of an epidemic without serious loss of time or the disorganization of the school work. The dis- missal or closure of the schools for an indefinite period as a measure of disease control has little to commend itself. A more recent development of school inspection is the exten- sion of its scope to include the physical defects of the children and make available provision for their correction. The scope of the examination made is most commonly limited to the ears, eyes, nose and throat, teeth, deformities, nutrition and men- tality. As a rule the methods of examination employed are necessarily not as detailed as those in ordinary clinical work, due to the lack of time and assistance. Their purpose is to call to the attention of the parents the existence of defects and to emphasize the need for their correction. The examina- tions should be made by a competent medical man and follow up work at the children's homes is best accomplished by nurses. They endeavor to enlist the cooperation of parents so that the suggestions offered by the examiner are carried out. REFERENCES Rosenau: Preventive Medicine and Hygiene. 3d, Ed., pp. 1077-1098. Cornell: Health and Medical Inspection of School Children. Gulick and Ayers: Medical Inspection of Schools. The Health of School Children. Bull. 4, 1915 and Bull. 50, 1915, Bureau of Education. Rural School Houses and Grounds. Bull. 12, 1914, Bureau of Education. Organized Health Work in Schools. Bull. 44, 1913, Bureau of Education. Schoolhouse Sanitation. Bull 21, 1915, Bureau of Education. Rural School Sanitation. Public Health Bull. 77, Public Health Service. CHAPTER XXXII AIR: HEATING AND VENTILATION i. Air is man's immediate environment and in relation to health serves two important functions. The oxygen supply which it furnishes may justify us in regarding air as a food, while it also serves an important function in the regulation of the body's temperature. It varies in the following directions: (a) Chemical Composition. — This is very constant out of doors all over the world. Variations in outdoor air are slight and are only found over small areas. On the other hand, the composition of indoor air is very variable, due to the constant admixture with expired air. It is a simple physical mixture, the approximate proportions being shown in the following table, ignoring rare and unusual constituents. Outdoor air per cent, by vol. Expired air, per cent, by vol. Oxygen Nitrogen Carbon dioxide 20.81 79-15 0.03 16.03 79-55 4-38 (b) Temperature and pressure show seasonal and altitudinal variations. (c) The possible moisture content varies directly with the temperature and pressure. (d) Odors are variable , being more numerous and concentrated in indoor air. (e) Air is subject to rapid movement, and to rapid changes in its temperature, pressure and moisture content. Air must be regarded as a most necessary and essential food. In this respect the nitrogen serves as a harmless diluent for the active oxygen, the essential constituent. The oxygen effects the combustion of the food eaten and stimulates digestion and metabolism. 2. By good air is meant air that is free from dust, smoke and odors, of moderate coolness and humidity, free from accumula- 282 air: heating and ventilation 283 tions of respiratory products and body excretions. It is usually outside air, the air of rural, residential or unsettled areas. 3. By bad or injurious air is meant air that produces discom- fort, which is chiefly caused by heat and humidity, and odors in the air of inclosed spaces. Odors are the chief cause of dis- comfort and their intensity is increased by heat and humidity. Ordinarily these conditions are due to the self pollution of air about a sedentary person, the aerial blanket about the individual being saturated with his excrement. Odors are of two types, extraneous and intrinsic. Extraneous odors include those due to gas works, bone boiling plants, rendering plants, slaughter houses, stables and meat markets. Intrinsic odors arise from the sudoriferous glands, from bad teeth, bad breath, gases from the stomach and rectum, or urine decomposing on the clothing. These are not detectable on chemical analysis. The necessary temperature and humidity to accentuate odors may be produced by the body, the heat being furnished by direct radiation and the humidity from the expired air and perspiration. 4. In addition air may contain certain various undesirable or injurious substances not due to respiration. Thus there may be present dust from various sources (metals, stone, wood, soil, manure, cotton, wool, etc.) soot and smoke. The latter are products of combustion and add sulphurous acid and carbon dioxide. The air of industrial establishments may be contami- nated by dust and fumes of varying kinds. These have already been considered. 5. Effect of Temperature and Humidity. — The human body is readily adaptable to temperatures from o degrees F. to 80. degrees F. Temperatures above or below these limits produce discomfort. Discomfort from both of these factors arises from the disturbances they produce in the heat regulating devices of the body. The bodily activities produce an excess of heat which must be lost or heatstroke will result. Heat is lost by (1) heat transfer which is affected by radiation, conduction, and convection, and by (2) evaporation (perspiration) whose amount diminishes as the surrounding humidity and tem- perature rise. Without free perspiration the temperature of the body rises if the external temperature goes above 70 degrees F. As long as free evaporation persists the heat production and heat loss are balanced. When humidity is high evapora- tion is lessened and the balance is maintained by an increased flow of blood to the skin and consequently an increase in the loss of heat by transfer. Humidity affects the heat output 284 PRACTICAL PREVENTIVE MEDICINE by (1) increasing the conductivity of the atmosphere for neat ^thus cold moist air is chilling) and (2) interferes with the evaporation of perspiration (thus warm moist air is ennerva- ting). Around a temperature of 68 degrees F. humidity exer- cises a minimum influence. Humidity should not exceed 70 degrees F. as measured on a wet bulb thermometer. Tempera- ture and humidity are perhaps the most important factors in ventilation. Warm moist air is not directly injurious. Chilling on leaving such an atmosphere may occur. When air about 80 degrees F. becomes saturated, evaporation no longer com- pensates for the decreased radiation and heat stroke may follow the rise in body temperature which follows. The effect of this temperature is diminished by light clothing. Cold damp air is injurious to poorly clad, improperly fed persons either in infancy or old age, or to those having kidney disease, rheumatism, disorders of metabolism or affections of the respiratory passages. Its effect is diminished by proper cloth- ing, exercise and an increased diet. Warm dry air produces the most comfortable sensations and is stimulating. Hot dry air causes an excessive loss of moisture and favors irritation and infection of the respiratory mucosa. 6. The relation of man to air varies in different climates. Thus in the tropics he needs no fire for warmth, no clothing except for modesty and no work to keep warm. The heating and ventilation of the home is of little consequence, since there is little home life. On the other hand in the arctics fires are needed for warmth, while fuel is scarce, and heavy clothing is required to conserve the body heat. As a consequence both heating and ventilation of the home is required. The temperate climate furnishes both of the above extremes during its seasonal variations. 7. Carbon Dioxid. — Carbon dioxid was formerly considered injurious and also an index of the wholesomeness of air. It is not irritating or poisonous. Its percentage cannot be taken as a guide to the fitness of air for breathing, and we can only employ its determination as a guide to the amount of rebreath- ing (vitiation) which has taken place, while it cannot be substituted for the more important determinations of tempera- ture, humidity, and motion. Ordinarily it never accumulates in quantities sufficient to cause injury. It is tolerated in quantities up to .10 to .13 per cent.; from 2 to 3 per cent, prod- uce increased respiration, from 7 to 8 per cent, produce air: heating and ventilation 285 distressing dyspnoea and 10 to 11 per cent, produce headache, nausea and chilliness. Suffocation will occur in an atmosphere of 30 per cent. 8. Heating. — The body must be regarded as a furnace, a radiator, a thermostat and a humidifier. It not infrequently produces more heat than is needed, whereupon no external heat is required. Less artificial heat is required by young persons, women, and by all persons when exercising. In sedentary life and old age the heat loss is in excess of heat production and then one needs to surround the body with an air blanket of a temperature that in winter will supply heat to the body. The young and active require an air blanket that will absorb heat. Thus a study should be kept warm and a gymnasium cool. Next to the body is a partial blanket of air enmeshed in the hair and clothing, which serves as an insulator. This is present except when a person is exposed to winds. Thinly clad persons, or persons who are poorly nourished, tend to overheat their dwellings, due to insufficient bodily heat production. Artificial heating as a practice antedates ventilation. At present, especially in large buildings, the two are frequently combined but it is a difficult master to secure satisfactory results. Artificial heating is usually with dry air. The capacity of win- ter air for moisture is greatly increased after heating, for when cold, even if saturated, it contains relatively little moisture. Artificial humidification is therefore required. Artificially heat is supplied by various means; (1) by open fire places, (2) by stoves, (3) by hot air furnaces, (4) by the enclosed circulation of steam and hot water, (5) by gas and oil stoves and braziers and (6) by electrical heaters. The first two of these methods usually improve the ventilation of the heated spaces, since the source of the heat is an open flame within the room, which requires a current of air for its active burning, and in order to avoid the smoke the gases are conveyed outside. These currents result in fresh air being drawn into the room from out of doors, Gas and oil stoves vitiate the air, since their gases of combustion are discharged into the room. If maintained in a small room actual danger may arise, due to high concentrations of carbon monoxid accumulating near the floor. 9. Ventilation. — The purpose of ventilation is to maintain the air of enclosed spaces in a condition that will result in the comfort of those using it. It does not necessarily imply the 286 PRACTICAL PREVENTIVE MEDICINE displacement of air, but should provide for its motion. It is impossible to make estimates of the proper allowance or condi- tion of air by any cubic foot per capita allowance. If the air in an enclosed space is maintained at not over 68 degrees F., without excess humidity and in slight motion a person will be confortable and the air can be rebreathed many times without discomfort. In a consideration of the air in enclosed spaces attention should be called to both the breathing zone and the breathing- cone. The breathing zone in a room includes the air lying within those limits from which a person draws air while either sitting or standing. If the air is stagnant and contains much smoke its limits will be visibly defined. The breathing cone consists of a more or less conical zone of rebreathed air surround- ing a sedentary person, whose apex is at his nostrils. The circulation of the air of an enclosed space breaks up these local concentrations of respired air. Ventilation is either natural or artificial. Natural ventilation is due to either: (a) gravity and diffusion, or (b) perflation and aspiration. The former represents the diffusion of air into a room through porous walls and the spaces around doors and windows. The warm air escapes and is replaced by cool air. It is important in the ventilation of small rooms. Perfla- tion is the ventilation secured by the removal of obstacles to wind pressure, such as that accomplished by the opening of windows. The effect of aspiration is shown by the air currents in flues and chimneys. It is assisted by the provision of movable chimney cowls which turn the vent away from the wind. Mechanical ventilation is the propulsion or extraction of air by means of fans or blowers whose operation is continuous. It is of two types: (a) the plenum system and (b) the vacuum system. In the first the air is forced in by a blower, having an intake at the ground level. In the second the air is withdrawn by an exhaust fan and the intake is secured by the seepage of air through walls and around windows. It gives rise to drafts. The plenum system is used in connection with heating systems and automatic thermo-regulation. As a rule it does not work satisfactorily if influenced by factors of natural ventilation. The air at the intake is washed to remove dust and also to humid- ify it, warmed by passage over steam coils and distributed through ducts. The best diffusion is secured where the discharge of warm air is near the ceiling, and the outlet is on the same wall air: heating and ventilation 287 near the floor. Both systems so far are only practicable for large buildings. 10. The Management of Halls and Large Rooms. — It is possible to so manage these enclosures during winter months that a large audience will be comfortable and alert during the period of their congregation. Good results will be secured if the hall is filled with fresh air at about 60 degrees before the audience congregates. The intakes are then closed. The audience should be watched closely and if a slight general coughing starts or if a scattering of women clear their throats, a little heat should be turned on. In hot weather every endeavor to secure the beneficial effects of perflation by removing all obstacles to wind pressure should be made. In enclosed halls and theatres where such is not possible the installation of artificial cooling systems based upon the circulation of cold brine, is of material value. REFERENCES Rosenau: Preventive Medicine and Hygiene. 3rd. Ed., pp. 661-776. Report of the Chicago Commission on Ventilation. 1914. Barometers and the measurement of atmospheric pressure. Circ. F. Instrument Division U. S. Weather Bureau. Psychrometric Tables for Obtaining the Vapor Pressure, Relative Humidity and Temperature of the dew point. U. S. Weather Bureau. CHAPTER XXXIII CERTAIN ASPECTS OF PERSONAL HYGIENE Many references to the care of the body in order to promote its proper functioning have already been made on previous pages in connection with some phase of preventive medicine. Here we shall briefly consider topics not heretofore mentioned. EXERCISE By exercise we mean the functional activity of the body, particularly muscular activity. The individual is in relation to the outer world in two respects, (i) by the sensations re- ceived, and (2) by muscular efforts which produce environ- mental changes. The muscular tissues make up most of the body bulk and are the seat of most of the metabolism. The body is so constructed as to be adapted to muscular exertion which is necessary for the maintenance of the body in normal condition. INFLUENCE OF EXERCISE (a) On Metabolism. — Exercise burns up carbonaceous ma- terial but does not increase the nitrogen consumption. The chief carbonaceous fuel is dextrose, which is stored up as a reserve fuel in the liver in the form of glycogen. During exercise the dextrose is oxidized to lactic acid, and if sufficient oxygen is present, to carbon dioxid. Not only does exercise bring into activity the muscular tissues, but all the other organs of the body as well. These activities involve both anabolism and kata- bolism. If exercise is so great that anabolism cannot build up what katabolism destroys, the individual loses weight. (b) On the Flow of Blood and Lymph. — This is at a maximum during work, due to an automatic dilation of the bloodvessels in the muscles. This is assisted by the pumping effect which the rhythmic heart action has on the veins. (c) On the Heart. — The heart readily adapts itself to exer- cise. This is accomplished by the metabolites, and by cerebral impulses to the skeletal muscles which inhibit the vagus tone. CERTAIN ASPECTS OF PERSONAL HYGIENE 289 (d) On the Arterial Pressure. — This is increased, due to a constriction of the splanchnic vessels to compensate for the dilation of the cutaneous and mucular vessels, thus increasing the pressure. The amount of the pressure varies with the exercise. Its function is probably to supply a head of pressure, so that if there is a demand on one part of the body the blood may flow there without leaving the rest unsupplied. A blood pressure of about 90 mm. of mercury will produce a decreased muscular efficiency. In a healthy person exercise will im- mediately cause the pressure to rise, it then soon falls some- what to a constant level which is maintained during the period of exercise, then falls below normal with rest and gradually is restored. (e) On Respiration. — The carbon dioxid produced causes a deepening and quickening of respiration. (/) On Heat Production and Regulation. — The increased fuel consumption of exercise results in the production of con- siderable heat. This requires the action of the heat regulating mechanism, so that the body temperature will not ascend too high. Exercise may cause a rise of as much as four degrees Fahrenheit above normal. (g) On Perspiration. — The stimulation of the sweat glands causes an increase in the amount of perspiration. By this means water and salts, chiefly the former, are eliminated. (h) On Digestive Processes. — Digestion and absorption go on equally well with rest and muscular exercise. On the other hand, exercise increases the appetite and decreases constipation by stimulating the activity of the colon. (i) On Slumber. — This is promoted by the development of a healthy fatigue. (j) On Muscular Tissues. — Those tissues not involved in exercise undergo an atrophy. On the other hand, exercise increases the size of muscle fibers but not their number. If the muscular fibers are overworked, permanent shortening results and the individual is said to be "muscle bound." EFFECTS OF EXERCISE Exercise produces the following effects which may be regarded as favorable, namely, an increase in the size of the exercised muscles, increased anabolism and a healthy fatigue. The following conditions that can result from exercise may be considered injurious, namely, pain from muscle soreness, muscle 19 290 PRACTICAL PREVENTIVE MEDICINE binding, production of inguinal and femoral hernias, and probably it also serves as a factor in the production of arterio- sclerosis. Exercise should never be excessive or potentially injurious. Of this the individual is the best judge. It should be avoided in conditions of great fatigue and in cardiac, vascular and pul- monary disease it should be employed with great caution. Interest in exercise is desirable. It is for this reason that locomotory games are hygienically valuable. FATIGUE This is the weariness resulting from muscular or functional activity. The vegetative activities of the body, such as the nutritive functions, reproductive activity, smooth muscle action, glandular activity, etc., are not subject to will power. These activities set their own pace and therefore are not subject to fatigue. On the other hand, the animal activities, including work and locomotion, are subject to the will and stimu- lation and may thus be set to limits beyond the individual's own welfare. The receptors, neurones and muscles are the sites of fatigue. (a) Receptor fatigue is fatigue of the end organs. We may particularly distinguish fatigue of the olfactory, auditory and optic end organs. Some odors affect the ability to distinguish similar or other odors, which must be considered a manifesta- tion of fatigue. Auditory fatigue only affects the ability to hear sounds in higher register. Optic fatigue is manifested by a reduced visional acuity. (b) Neuron fatigue occurs centrally, the axone being con- sidered indefatigueable. Morphologic changes in the nerve cells and nucleus with a chromatolysis are observable, and physiologic changes, as shown by a rise in the threshold value between neurons, are seen in the spinal reflexes. (c) Muscle fatigue may reside in the end plate or muscle fiber. The end plate may be fatigued while the muscle is still capable of contracting. The muscle contraction varies with constant or variable loads. With a constant load the con- tractions will finally cease, while with a variable load they will go on indefinitely. The rate at which they contract is as im- portant as the load in the production of fatigue. The fatigued muscle is less irritable to stimulation, but increased stimulation will produce an increase in the height of contraction. The CERTAIN ASPECTS OF PERSONAL HYGIENE 291 reaction of the muscular protoplasm changes to acid from neu- tral or alkaline, due to the formation of sarcolactic acid and monopotassium phosphate. The acid is dissipated by outward diffusion, or oxidation to carbon dioxid. As a consequence lactates and lactic acid may appear in the blood and urine following fatigue. Muscular fatigue is due to the accumulation of these waste products in either the muscles or the blood. If in the muscle their accumulation may be due to the failure of the blood stream to remove them. The massage of a fatigued muscle assists in the removal of the fatigue products by the circulation. Recovery is also hastened by oxygen. The ac- cumulation of fatigue products in the blood affects muscles other than the ones involved in the exercise, thus local fatigue becomes general. Fatigue is temporarily overcome by excitement. In both laziness and fatigue work is done with a sense of effort, probably due to a rise in the threshold value, and to the accumulated waste products. When the threshold value of the neuro-mus- cular junction rises as fatigue progresses, the innervation spreads to other groups of muscles in order that the work may be accomplished. This brings more nerves and muscles into play and increases the amount of metabolites in the circulation and hence produces a greater sense of fatigue. As fatigue appears the movements of the muscles become less exact and their co-ordination is less perfect. This has a bearing upon industrial accidents as shown in the following figures. TABLE XI Industrial Accidents in the German Empire, 1887 Morning Evening Hours No. of accidents Hours No. of accidents 6-7 445 1 2- 1 587 7-8 794 1-2 745 8- 9 8i5 2-3 i,o53 9-10 1,069 3-4 1,243 io-ii i,594 4-5 1,178 11— 12 1,59° 5-6 1,306 Fatigue also reduces the rapidity and accuracy of action and also diminishes the extent of mental control. There is also an increase in irritability and irascibility. Garrulity and 292 PRACTICAL PREVENTIVE MEDICINE uncontrollable laughter may appear to an extent which is almost hysterical. Normally fatigue is a protective sensation indi- cating the need of rest. It reduces the general sensibility of the body. Nervous fatigue, on the other hand, involves the activities of the central nervous system itself. It is of importance be- cause the changing racial habits of our times require constant alertness, necessitating quick adjustments rather than much muscular work. REST OR RELAXATION Rest permits the accumulations of waste to be excreted and the destroyed material to be replaced. The greatest rest is achieved during sleep. Sleep is favored by warmth and quiet, especially toward the senses of sight and sound, "com- fortableness," and complete relaxation. It is also aided by a neutral bath or any dull monotonous sound. Brain workers need less sleep than laborers. Eight hours is the average duration of sleep normally. A change of work also permits of rest, especially with mental work. Long periods of mental work are unfavorable to mus- cular work and vice versa. If either are in excess one had better rest than change from one to the other. BATHING The sebaceous and perspiratory secretions of the skin require more or less frequent removal. This is best accomplished by bathing or washing the body in water. Those localities where the sweat is most likely to be poured out should be bathed daily in order to prevent accumulations which produce un- pleasant odors. Furthermore a clean skin is less likely to be diseased than a dirty one. Bathing reduces the likelihood that body vermin might be able to establish a foothold. Too strongly alkaline a soap should not be used or ,the skin will become dry. The oil removed should be replaced by inunctions with lanolin or cocoa butter. Lastly the bathing of the hands and face, especially before eating and the avoidance of intro- ducing the fingers into the mouth until after they have been washed, is an important safeguard against the introduction of infective agents by contact. The 250,000 cold spots and the 300,000 warm spots are stimulated by temperatures differing from that of the body. CERTAIN ASPECTS OF PERSONAL HYGIENE 293 Thus in bathing the skin is stimulated by thousands of afferent stimuli. Baths are designated according to their temperature as follows: Cold 65 degrees F. Cool 65-80 degrees F. Tepid 80-90 degrees F. Warm 90-98 degrees F. Hot 98 or over. Cold baths stimulate and are employed for that purpose. A reaction is induced by an exposure to cold of from ten to thirty seconds duration. The immediate effect consists in the dilation of the internal blood-vessels, a contraction of the cutaneous vessels, "goose flesh," cutaneous pallor, a sensation of cold, shivering, an increased heart rate which soon decreases, with a decreased respiration. The secondary effect is known as the reaction. It is manifested by a slow and deep respiration, a reddening of the skin as the blood returns to the surface, accompanied by a feeling of warmth, perspiration and a sense of exhilaration. A warm body and skin before the bath tends to favor the reaction. The temperature of the bath should be as cold as may be tolerated. Cold baths should not be em- ployed in infancy, old age, exhaustion, or fatigue. Hot baths are better for purposes of cleanliness after muscular work resulting in soreness. They are useful when the irritabil- ity of the person is increased or when one has insomnia. Very hot baths of ioo degrees F. produce a reflex resembling the effect of cold baths. The enervating effect is manifested by a lower irritability or indisposition for muscular work. It may be overcome by a cold dash. A bath at the body temperature produces very slight effect. It has a calming effect and is used in the treatment of the insane. It is best for weak individuals or where cleanliness is the object of the bath. Prolonged bathing may produce the following ill effects, namely, nausea, faintness, giddiness, weakness, dyspnoea, and a subnormal temperature. CLOTHING Clothing is worn both for purposes of modesty and to main- tain a constant body temperature. In this connection it must be borne in mind that the skin is the most important organ in temperature regulation. Clothing aids in protection from the effects of a lowered temperature by holding warm air enmeshed 2Q4 PRACTICAL PREVENTIVE MEDICINE (insulation), so that the body lives in a temperate climate, and also by influencing conduction, convection and evaporation. Heat losses by conduction are favored by clothing made of plant fibers, since these conduct heat outwards better, although heat losses by this means are relatively slight. Furthermore the extent of the loss is reduced by the air enmeshed in the fabric, which factor is however greater in fabrics made from animal fibers, since their elasticity is less affected by laundering. Heat losses by conduction are favored by anything which permits the warm air close to the body to be blown away. The degree to which this occurs is influenced by the porosity of the clothing. Of fabrics, flannel is the most porous and silk the least. Leather, paper and rubber prevent heat losses by this means. If the spaces in the fabric be filled with water, the losses by evaporation as well as by conduction are increased. Thus wet clothes may chill the skin, and the cessation of exercise while the clothing is wet may be dangerous. Wool has the greatest hygroscopic power of all fabrics, so that water evaporates slowly from it. An ideal fabric would permit sweat to evapo- rate when poured out and would not stay wet when sweating ceases, or do away with the enmeshed air when wet. The fabrics which make the most suitable clothing to be worn next to the skin in summer and warm climates are cotton or close meshed linen. For cold climates and for individuals who get little exercise wool is best. There are differences of opinion concerning those best adapted to individuals likely to get wet. Some advocate wool, for it absorbs sweat and still enmeshes air. Others object to it as it does not permit quick heat losses and dries slowly. Others favor cotton, especially coarse meshed fabrics, for permitting a quick heat loss. Objections raised to it are the fact that it wets through rapidly and no air spaces are left, while the heat losses maybe too rapid. Outer clothing in the summer is worn chiefly for appearances. It should be as permeable as possible and for this purpose cotton or linen are best. In winter woolen is the fabric of choice. If one is in the wind, impermeable goods should be selected. If a person lives mainly indoors in the winter the outer clothing need be the only change of adaptation. If one exercises in the cold do not make any change except to leave off the outer clothing while exercising. The color of clothing has no effect on the radiation of the heat. Those colors which reflect the most heat absorb the least. CHAPTER XXXIV DOMESTIC SANITATION The sanitation of the home does not present any features that distinguish it from other problems of sanitation. ^ Rather it is the application of principles we have discussed in detail elsewhere in their particular relationship to the home. Therefore we cannot expect to find that very much new material will be presented at this time. LOCATION Other things being equal, an elevated well drained situation is preferable for the location of a dwelling. The importance of this factor is probably not so great as was considered at one time, but nevertheless should not be ignored. Poorly drained loca- tions will permit accumulations of water close to dwellings and hence result in mosquito breeding, the contamination of wells is made more likely and in an effort to fill or raise the ground level, poor filling material is apt to be used, so that rat harbour- age on the premises is favored. CONSTRUCTION The various materials from which dwellings are constructed are about equally valuable from a hygienic standpoint. _ In other words it is possible to construct dwellings of equal hygienic value from wood, brick, stone, concrete, or any other material. An important point in construction, regardless of the materials used, is to make the dwelling rodent proof. This is largely a matter of neat and careful workmenship, especially in the case of frame dwellings in which special precautions must be ob- served. The building must fit its foundation closely and all spaces between the floors and walls sealed tightly with brick or cement through which rodents cannot gnaw. This can t>e done by filling the spaces between the studdings above the sills for a distance of six or eight inches with mortar or bricks. Like- wise the openings in the basement floors, and walls, as well as the basement ceilings through which pass conduits, drain pipes, 295 296 PRACTICAL PREVENTIVE MEDICINE water, and gas pipes etc., should be tightly sealed with cement or flashed with tin. Knot holes should be tightly sealed with sheet tin. The provision of smooth, tight floors is likewise an important matter in promoting the future cleanliness of the dwelling, since less labor i& required in keeping such floors clean than those which are rough and have large cracks. LIGHTING Every dwelling should be so situated that at some time of the day each of the sides will receive the sun's rays. Little can be said in favor of the type of dwelling construction common in large cities, where for blocks dwellings or tenements occupy the entire lot space, only presenting free wall space at the front and rear. The interior rooms of such dwellings receive very little natural illumination. The type of construction we earlier recommended is best, for first it permits full advantage to be taken of the brightly diffused sunlight for the illumination of the dwelling's interior during the day, and second, each room for some period of the day will have a greater or less amount of direct sunlight gaining entrance, and thus be benefited by its germicidal activity. Furthermore as we shall presently see, such construction enables the fullest advantage to be taken of natural ventilation. Narrow streets and high dwellings, particularly those of the apartment or tenement variety, restrict the amount of sunlight available to adjacent buildings as well as to the street. Accord- ingly provision should be made to regulate the heighth of build- ings in proportion to the width of the street they face. No interior rooms should be occupied as living, sleeping or working rooms, which do not have outside windows. Large windows permitting the introduction of the maximum of sunlight and fresh air are desirable. Attention should be paid to the location of the windows on opposite sides of the dwelling, as well as the location of intermediate doors and win- dows, so that free passage of air across the house can be secured when the windows are open. Artificial illumination is of course necessary for nights and dark days. Various methods are now available, from the candle, kerosene, gasoline, or acetylene lamps to gas and electricity. Electricity is probably the best when available, since the fire danger is the least, it does not consume oxygen from the air and the most brilliant illumination is possible. DOMESTIC SANITATION 297 The recent introduction of indirect illumination by means of light rays reflected upon the ceiling from concealed globes is undoubtedly the best means of artificial illumination. The room is lighted by a diffused glow, more nearly imitating natural illumination than any other means. Eye strain is avoided if those seated in the room so place themselves, or the lights are so situated, that the direct rays do not fall on the face. Those reading or doing work which requires close inspection should preferably seat themselves so that if right handed, the light falls over the left shoulder. Delicate work should be brightly illuminated by shaded lamps, in addition to those shedding a diffuse light over the apartment as a whole. HEATING AND VENTILATION These questions have already been discussed in detail. We shall only refer here to the attention which should be paid to the sleeping quarters when in use. Otherwise the stagnation of air in the breathing cone and the breathing zone will become very marked. Every provision should be made to permit the freest entrance of fresh air. The open air sleeping porches possess a distinct hygienic value. If asleep in a room the air of which is stagnant or sluggish, the concentration of the expired air in the breathing cone and the breathing zone reaches a maximum, due to the fact that an individuals relative position changes but slightly while at rest. The greater the motion of the air the less will be the stagnation of the air in these zones. Outdoor sleeping is of a distinct advantage in the prevention and treatment of tuberculosis. One may safely enjoy it at a tem- perature considerably below zero by providing sufficient bed covers and a hood. OVERCROWDING Hygienically there is little in the tenement or apartment house that is fundamentally sound. The ideal dwelling is a separate and distinct structure for the housing of each familial unit. The former are only economically justified by the high price of building land. Too often we find that expense in this connection leads to a reduction in the floor space of the apart- ment designed for only one family to the point where the occu- pants are constantly in each others society. Where rents are high this objectionable factor is intensified by the question of sub-leasing rooms to other individuals or families, as a conse- 298 PRACTICAL PREVENTIVE MEDICINE quence of which the overcrowding is intensified. Thus it is not uncommon to find a single family with perhaps three or four children occupying only a single room or perhaps renting a por- tion of their altogether inadequate space to another individual or family. Under these conditions of over crowding, all ages and sexes must lead a life of the greatest intimacy; privacy is im- possible and immoral acts or sexual precocity are stimulated. Adequate ventilation does not usually exist, opportunities for the transfer of human secretions and excretions reach a maxi- mum and consequently contact transfer is always favored. A safe rule is to consider that each space occupied as a dwelling should provide at least one room for each member of the family, and not less than one room for each two individuals. EXCRETA DISPOSAL We will not consider this question from the standpoint con- sidered previously. The prompt and regular elimination of the feces and urine bears an important relationship to health. Irregularity in these habits promotes constipation, and also the absorption of toxins from the fecal residue that impair health and mental efficiency. Consequently the education of an individual in the regular evacuation of the bowels, with most persons at least once daily, is of great importance. This is facilitated by providing a place for the evacuation of the bowels and bladder kept suitably clean and inoffensive, and where an individual is not exposed to extremes of temperature or incle- ment weather. The indoor closet must be regarded as a great improvement in domestic sanitation and one which has well nigh reached perfection. Any of the types of water flush closets on the market at present may be regarded as satisfactory. While the operation of these is dependent upon an abundant supply of running water, yet those whose homes are without running water can avail themselves of the convenience of indoor facilities for the discharge of the excreta. One of the best means for this purpose are the so-called chemical closets, in which the excreta are received in a pail or tank of caustic solu- tion, which effects their disintegration and disinfection. These however are not automatic and require attention. If neither of these means are available, the pit privy suitably located with regard to the water supply, must be regarded as the next best substitute. It should have a water tight pit or vault, and be of fly proof construction. Various types of DOMESTIC SANITATION 299 privies have been designed and have given varying degrees of satisfactory service. All that are water tight and fly tight will probably give satisfactory and safe service if properly attended, though some require frequent attention, especially the changing of the receptacles for the receipt of the excreta. Since such details are apt to be neglected and hence interfere with the satisfactory operation of the privy, the types recommended above are best as they require the least attention. Isolated rural dwellings that, have a supply of running water may enjoy the advantages of an indoor closet. The sewage may be received into a leaching cesspool or septic tank, preferably the latter, the overflow from which is disposed of by sub-surface irrigation. Such disposal methods must be care- fully located with regard to the domestic water supply. SCREENING All doors and windows at least should be covered with a suitable screen. For this purpose brass, copper or galvanized wire netting, of at least 18 meshes to' the inch, is preferable owing to its longer life. These should be carefully fitted and kept in repair. Fire places and chimneys must be scrutinized since it may be necessary to screen these. It is preferable to screen entire porches and galleries rather than the windows and doors opening out upon them. Before a house can be con- sidered fly or mosquito tight it must be ascertained that no cracks or holes exist in the floors, walls or ceilings through which these insects can enter. PERSONAL HYGIENE Personal cleanliness bears a very close- relationship to health as we have already seen. Facilities for its promotion should therefore be found in every home. It is perhaps made the easiest by means of running water and the large porcelain bath tubs and wash bowels now available. Lack of these facilities should however not deter one from frequent cleansing of the body, although the process is made less convenient by their absence. THE KITCHEN Two aspects of the kitchen demand our attention. The first of these is the care devoted to the temporary preservation of perishable food, either before or after cooking. Cold is the 300 PRACTICAL PREVENTIVE MEDICINE means universally employed for this purpose. Where not employed bacterial decomposition may make certain food stuffs unsafe for consumption, especially milk for infant feeding. The employment of ice in insulated boxes or cabinets commonly known as refrigerators is very common. In the absence of ice, such food is sometimes suspended in wells, thereby jeopardiz- ing both the food and the well, or similarly suspended in pits dug especially for this purpose. Such means will temporarily retard bacterial decomposition until the food is consumed. It must be borne in mind that the coldest situation in a refriger- ator is below the ice. In the absence of these facilities, some advantage may be secured by placing the vessel obtaining the perishable food in another vessel which in turn is placed in a vessel containing water. Coarse cloths are placed over the inner vessel extending down into the water. The whole is then set in a position where air currents will cause the rapid evapora- tion of the water in the cloth, which rises by capillarity. A second point is the disposal of the kitchen refuse or gar- bage. This should be carefully drained to free it from all water, and then wrapped in a paper before being placed in the garbage can. Or if a collecting service is not available, it may be burned in a coal or wood stove, buried, or fed to chickens or swine. It should never be deposited upon the surface of the ground close to the house, as it attracts flies and rats and the sour odor which develops during decomposition is very annoy- ing. Toilet and washing facilities should be conveniently situated to the kitchen, especially where servants are employed. REFERENCES Overton and Denno: "The Health Officer," Chapter XXXVII. SECTION VII DEMOGRAPHY CHAPTER XXXV STATISTICS OF POPULATION i. Demography may be defined as the application of statis- tical methods to the study of populations. As such its scope is as broad as the activities of mankind. Our interest in it is exceedingly narrow, only relating to those statistics which indicate the changes and fluctuations of a population, as well as the degree of its health. This narrow field of demography is commonly designated as vital statistics. The subject of statistics may be defined as the numerical statement of facts for study and comparison, and the collection of data and its abstraction for generalization. 2. All studies in vital statistics are based upon the population of the area under consideration, and are necessarily expressed in terms of population. Statistics of population for the pur- poses of vital statistics must show the number of inhabitants of an area, classified by age, sex, nativity, race and occupation. More detailed information would be desirable but the labor of making more detailed analyses is commonly too great for the available funds. This fundamental information regarding a population is obtained by a census enumeration. The standard census in the United States is conducted by the Federal Government. These have been taken every 10 years since 1790. In addition many states take decennial censuses at intervals mid-way between the years of the Federal census. In order to avoid omissions and errors it is desirable to take the censuses at a time of the year when the maximum number of individuals will be at their homes. The spring is considered the best time of the year for this purpose. Actually the census canvas requires several months for its accomplishment, yet for simplicity sake it can be, and is referred to a given date. Thus the 1910 census was referred to April 15th. 301 302 PRACTICAL PREVENTIVE MEDICINE Of errors in census enumerations, the most important are the following: (i) Overlooked persons. It is not possible to require that the entire activities of a nation be suspended while the great inventory is being taken. Some individuals, espe- cially those who are traveling are bound to be overlooked, others may be counted twice and unscrupulous enumerators or officials in charge of areas where a great civic pride in rapid population increases exists, all contribute their quota of error. On the o50 a K n u 3 30 2 20 n n n r V \l n LIU T. II *■ V in AGE DISTRIBUTION IN MASSACHUSETTS FROM 1905 STATE CENSl VOLUME 1, POPULATIOt AND SOCIAL STATISTICS, P - F JS i 555 U L j^ ^ K 10 20 30 40 Ag& in Years .50 60 70 80+ Fig. 119. — Age distribution in Massachusetts. (Whipple, "Vital Statistics," John Wiley and Sons.) whole however, the Federal enumerations probably represent the most accurate enumeration possible, and the actual error is but a small fraction of one per cent. These censuses should always be taken as the standard. (2) A second common error results from misstatements regarding age. These are of two types. The 'age recorded should be the age of the individual at the last birthday. In the case of children up to five it is very common to find the stated age is really the age at the next STATISTICS OF POPULATION 303 birthday. On the other hand adults show a tendency to express their age in round numbers, thus a person of 59 will give 60 as their age, or 60 for 62. As a consequence when the population is plotted according to age we find a great increase in the num- ber of persons at each of these decennial ages over and above those at intermediate ages (Fig. 119). 1,200,000 100,000 1820" 1830 1840 1850 1860 1870 1880 1890 1900 1910 1920 Pig. 120. — Immigration to the United States, 1820-1917. (Whipple, "Vital Statistics," John Wiley and Sons.) Populations are never stable, continuous fluctuations is the rule either increasing or diminishing (Fig. 123). The most important as well as the most variable factor in these fluctua- tions are migrations, . either a moving out (emigration) or a moving into an area (immigration) (Fig. 120). Migratory populations show a large relative proportion of adult males. As a result of these changes we may find that the entire charac- 304 PRACTICAL PREVENTIVE MEDICINE ter of a population has changed, or its distribution within an area has been altered. Immigration is an important factor in territory under-going industrial development, while emigration is more commonly observed from areas of industrial stagnation or where competition is keen and sharp. The other constant factors in population fluctuations are the increases resulting from births and the losses arising from deaths. Where the effect of migrations are not felt, a gradual increase is usually observable, the increments from births being usually in excess of the death losses (Fig. 121). On the other hand, in IS75 I8S0 t885 1990 »95 BOO f9 X 810 £8 / ft / n ^1 5 , £4 22 J \ s K i s £0 / \ / \ L ;e \ / s / r 18 1 \ 1 — / 16 A 12 JO 8 6 A 2 Fig. 121. — Births and deaths (exclusive of stillbirths) per 1,000 population per annum — Massachusetts — 1871 to 1911. (Trask: Suppl. 12, P. H. Rep.) some countries, such as France, the death rate may nearly coincide with, or at times exceed the birth rate (Fig. 122). 3. The great expense of census enumeration, as well as the time necessary for the analysis of the vast bulk of data secured prevent the performance of annual enumerations. Conse- quently where a population basis is required for the data of the intercensal years, estimates must be employed. For this two methods are available, the arithmetical and the geometrical. (a) Arithmetical estimation: This method infers that a constant yearly increase in the number of the inhabitants has STATISTICS OF POPULATION 3°5 taken place between the censal years and that the same increase will occur for some years following the last census. For employ- ment, divide the difference between the population returns of the censuses by the number of years between them. Multiply the quotient by the number of desired years following the census and add the result to the proper census population. Thus supposing the population of an area was 64,410 in 1890 and 82,624 m 1900 and we desire to estimate the population in 1898 and 1904. Thus Pop. 1900 Pop. 1890 82,624 64,410 1885 1990 1895 000 1905 1910 26 24 & in. hi 22 \ \^*^ L >ec th 5 % / / 1 /* \ y^ > 30 A , | $ £0 V nf ps i\ »JS 10 M c #. s<> Fig. 123. — Population of the United States, in millions, 1810 to 1910; and of Massachusetts, in hundred thousands, 1765 to 1910. (Trask, Suppl. 12, P. H. Rep.) 0.1549 divided by 10 equals 0.01549, the log. of 1.036 or (1 plus r) of our formula. 0.01549 times 4 equals 0.062. log. 0.062 plus log. 4.8451 equals 4.9071, which is the log of 80,750, the 1904 population. Each of these methods is best adapted to populations pre- senting certain characteristics. The geometrical is best adapted to populations whose increase is due to the excess of births over deaths, while the arithmetical is best adapted to areas where growth is largely due to immigration. The latter is considered STATISTICS OF POPULATION 307 best adapted for use in the United States. It is to be noted with these two methods, that in intercensal years the geometrical method will give results less than the arithmetical, but for postcensal years its results will be greater. Where long time estimates are required, such as are required for planning the scope of public improvement for a long term of years, neither of these are reliable. It is better to compare the area with the development of other similar areas but of larger population, subsequent to the time when their popula- tions were the same as that of the area under investigation. I I Less than 50 per cent Mai ITH1 50.0 to 51.9 g%% 52.0 •• 53.9 ^^ 54.0 •• 55.9 1 I 56.0 •• 57.9 gll 58.0 •• 59.9 £SH1 At least 60 per cent Male Fig. 124. — Per cent, male in total population for states and territories, 1900 (Bull. 14. Bur. Census.) These methods are not always applicable, as for example, where a population shows stationary indications or has even declined at the last census. Less accurate methods of estima- tion only are available and these unfortunately are of no value in vital statistics. Thus we may estimate the population from the ratio of persons per dwelling, if the number of the latter are known. For the United States as a whole this is 5.2. A dwelling is defined as any building or set of rooms housing a family. Or the number of school children or trolley passengers may furnish a rough guide. 4. The commonest data tabulated from census returns rela- tive to the composition of the population relates to sex, age, race 3 o8 PRACTICAL PREVENTIVE MEDICINE (Fig. 125) nationality and conjugal condition. Of these age, sex and race are the most important for use in vital statistics. Male births are in excess of female in proportion of 21:20, but male deaths are in excess of female deaths. The greater migra- tory habits of males leads to a diminution in the relative pro- portion of the sexes in older communities, so that females are in excess. Conversely in newly settled areas males will predom- inate (Fig. 124). 5. Another population distinction of importance from our standpoint relates to the distinction between urban and rural 1 1 Les9 than 1 per cent. v.*>;a 1 to 5 per cent. E5553 S to 12 j per cent. ESS 12J to 26 per cent. km 25 to 37 J per cent. Effl 37} to 50 per cent. IB 50 per cent and over. The heavy lines (■») show geographic divisions. Pig. 125. — Percentage negro in total population by states, 1910. Bur. Census.) (Bull. 129. populations. Distinction is upon a purely arbitrary basis. Thus in the 1870 census towns of 8000 population or less were considered rural, in 1880, 4000 or less and in 19 10, 2500 or less. Thus it can be seen that these distinctions have not been made on a constant basis. In the 1870 census 32.90 per cent, of the country's population was urban and in the 1880 census 37.3 per cent. 6. Another important point is the determination of the density of population, that is, the number of individuals per unit of surface area. Most commonly for larger areas such as states and countries the population is divided by the total area in miles or acres (Fig. 126). For comparative studies in an STATISTICS OF POPULATION 3°9 urban population it is perhaps better to analyze data according to ward populations rather than by density per acre. In considering population fluctuations within civil areas in successive years it is important to ascertain if any changes have been made in the geographical boundaries of the area under con- 310 PRACTICAL PREVENTIVE MEDICINE sideration. Large increases may be due to the annexation of territory with a considerable population, and sudden increases thus appear. 6. Value of Vital Statistics. — In any consideration of various facts concerning a large body of individuals, such as the popula- tion of a city, a state or a nation as regards births, deaths or individuals, it is impossible to consider the individual by him- self, but rather all must be considered in the aggregate if any clear conception is to be gained of the influence of economic or morbific factors. Considered as individuals we would lose sight of the mass. As a consequence, it is necessary to employ statistical methods to avoid confusion and to enable the trend of events to be clearly discerned. In any employment of statistical methods it is of course necessary to express facts by figures, and as expressed by Whip- ple: "When figures are used to express facts, and when logical processes are applied to figures, divorced in the mind from the facts for which they stand, it is easy for fallacies to creep in without being recognized; it is easy to compare things that ought not be compared; to generalize from inadequate data and so commit all sorts of illogical errors. Thus the unscrupu- lous may fool the unwary and the innocent fool themselves. Hence to use statistics properly one must be able not only to visualize the facts but to think logically." Quoting Whipple further: "Vital statistics are useful for many purposes. To the his- torian they show the nation's growth and mark the flood and ebb of physical life; to the economist they indicate the number and distribution of the producers and the consumers of wealth; to the sanitarian they measure the people's health and reflect the hygienic conditions of their environment; to the sociologist they show many things relating to human beings in their rela- tions one with another." "Vital statistics are not to be collected and used as mere records of past events; an even more important use is that of prophesying the future. The health officer should study them as soon as received and not wait until some convenient day when other work is slack and then merely tabulate them and make averages for formal reports and permanent records. Vital statistics, especially those of morbidity, should be studied in the making and just as the meteorologist reads his instruments daily in order to forecast the weather and give warnings of the coming hurricane, so the efficient health officer will daily study STATISTICS OF POPULATION 311 the reports of new cases of disease in order that he may be fore- warned of an impending epidemic and take measures to check its ravages." REFERENCES The Story of Census, 1790-1916. Bureau of the Census. Federal Estimates of Population and Federal Supervision of Local Censuses. Bureau of the Census. CHAPTER XXXVI STATISTICS OF BIRTHS AND DEATHS BIRTH STATISTICS Birth records are secured by registration in those civil divi- sions that secure sufficiently complete records to be of value. Legal responsibility is placed upon physicians and mid- wives to make reasonably prompt returns in accordance with prescribed rules and upon special forms (Fig. 127), to designated officials. The securing of reasonably complete birth records is a difficult matter and at least in the United States is probably nowhere 100 per cent, complete. Birth records are of value to individuals whose births are recorded from the standpoints of giving legal proof of citizen- ship, age and parentage, all of which are sometimes necessary to secure passports, residence, to secure employment, to prove legitimacy, to inherit property and in numerous other ways to enable an individual to enjoy the rights of citizenship. From a public health standpoint birth registration is of importance as it enables health authorities to intelligently combat infant mortality by means we have already considered. All children who breathe after birth should be registered as births, while still births should not be recorded in either the groups of births or deaths, but placed in an independent group. A rough check on the completeness of registration may be secured by comparing the total number of births registered by the number of children under 1 year of age enumerated in any census year. The births in a given population may be expressed for com- parative purposes in the following ways: (a) The rate or number per 1000 of the entire population. (b) The rate per 1000 women of child bearing age (15-45). (c) The legitimate birth rate per 1000 married women of 15-45- (d) The illegitimate birth rate per 1000 unmarried women of 15-45- The first of these methods of expression is known as the crude birth rate, and is subject to the same objections when employed for comparative purposes that are raised to the crude death 312 STATISTICS OF BIRTHS AND DEATHS 313 rate. These will be considered later. These rates are com- puted in the same manner as the death rates, as shown later. United States Standard Certificate of Birth. *• u « » « 1 e t- s I 5 - I z 5 3 r q Z E Z Z u e » I 5 « I 1 . « u. = « ? S u J « : 1 > - ■•: s u * =1 -e C s 3 e =•0*5- Ms! 3 a. .; I I! 1 5,! * PLACE OF BIRTH County of ..... .... Township of 1 Village of ■— FULL NAME OF CHILD STANDARD CERTIFICATE OF BIRTH, Registered No. — .- ....Ward) [f-ciltd tioot ;tt D*a«j, E*k« iappiemtsUMi Terpen, uiirecteA Sex of Child 1 T>b,tripM, 1 v other! 1 of ffctl CERTIFICATE OF ATTENDING PHYSICIAN OR MIDWIFE* I hereby certify that I attended the birth of this child, who * the data above stated. (Signature) . . should maJce this re e of life aftr, (I-tjtician cr Midwife) no added from a supplemental Address— 2 II SUPPLEMENTAL (Thii r (SI Place of birth « (Ee^irtra Hon dtatr.rt) SEX OF CHILD' Twin." triplet, H Nraber" rfffirtt (D.7) (T«M] ! FULL* FATHER ' NAME FULL' MAIDEN MOTHER ■ * wwrcl tj l <-"-**"**" IS "'° 8 °" U "*'° m ' ) nude ikr. original) Registered, Number * .... I HEREBY CERTIFY that the child described herein has Fig. 127. — (Trask, Suppl. 12. P. H. Rep.) The second method of expression gives a better idea of the fecundity of a population, while the third and fourth methods 314 PRACTICAL PREVENTIVE MEDICINE when used together give a still better idea. These should be employed when it is desired to compare the births in one com- munity with those of another. The frequency of births varies widely with different races and nationalities, in different parts of a country, state or even a city. The crude rate may vary in the extreme from 22 to 39 per thousand. The following factors influence the birth rate: (a) the age distribution of the population; (b) the propor- tion of the two sexes; (c) the number of first marriages; id) the age at marriage; (e) the economic condition of the country, and (/) social and hygienic conditions. MORTALITY STATISTICS Death records are likewise secured by registration. On the other hand, it is fairly easy to secure complete returns if a death certificate is required before a burial permit is issued. The death certificate (Fig. 128), a portion of which dealing with the cause of the death is filled out by the attending physician, is filed with the proper authorities by the undertaker. Errors are not uncommon on these certificates and the authorities should require their correction before certificates are accepted. The original data may be incorrect, due to mis- statements by members of the decedent's family. The state- ment of the cause of death given by the physician may be inaccurate due to an erroneous diagnosis or a desire to shield the feelings of the decedent's family. One of the most important aspects of the physician's obliga- tions in connection with mortality reporting is the statement concerning the cause or causes of death. Two grave errors are possible which seriously interfere with the accuracy of mortality returns. The first of these possible errors relates to mistakes in the diagnosis of the condition actually responsible for death. Any physician who has followed a considerable series of cases to postmortem is familiar with the fact that post- mortem examinations not infrequently fail to corroborate the antemortem diagnosis, even when the patient had been under the care of extremely competent physicians. Where the post- mortem examination serves as a check these errors are usually revealed, but where postmortem examinations are not made, and relatively few bodies are examined postmortem, these errors remain concealed. Another source of error is the em- ployment by physicians of vague or inaccurate terms in stating STATISTICS OF BIRTHS AND DEATHS 3*5 the cause of death, so that it is difficult to associate the stated cause with any definite pathological condition. The first of these possible errors can only be reduced by greater refinements in the art of diagnosis and of greater efficiency on the part of the medical profession in their application. The second can be reduced by care. The Census Bureau is endeavoring to secure an improvement in the last direction by familiarizing physicians with the standard International Lists of Causes of 132 S - i of »;■'._— CM fimril nxhire of lednttry, Z • * • iH. SHI ;RE BY C e RT l F" V, That I attended deceased from lat 1 last 5 nd that de CONTRIBUTORY- 18 V 10NAMEOFFATHER £ j 5 I 12 MAJDEN NAME OF MQTHER Did an operation precede death 7 Was there an autopsy? What test confirmed diagnosis ? . (81 gned) , 19 (AdoVe*) 12 BIRTHPLACE 0FM0THER(dt7 or toirn). HoioasAi- (Sm r e side for additional space.) ACODXBT1L, BU lTTTur , or 19 PLACE OF BURIAL, CREMATION, OR REMOVAL DATE OF BURIAL 20 UNDERTAKER Fig. 128. Death, and also the indefinite, objectionable terms whose use should be avoided. The Bureau publishes a very convenient Docket list of the proper terms. Death records serve the following purposes; (a) they aid in the detection of crime, making the concealment of murders very difficult; (6) assist in the transfer of inherited property; (c) facilitate the settlement of life insurance, and lastly (d) in- dicate the extent and changes in population produced by death. From a public health standpoint they have some value in the 316 PRACTICAL PREVENTIVE MEDICINE control of disease, especially where morbidity reporting does not exist. Their greatest drawback in this connection is due to the fact that the information they give is tardy and also' incomplete from the standpoint of revealing all disease in- cidence. A greater value they possess in this connection is in permitting a certain check to be made on the completeness of morbidity reports. STATISTICS OF BIRTHS AND DEATHS 517 Deaths among a given population are expressed in rates fundamentally similar to those employed in expressing births. The most common rate employed is the general or crude death rate. This may be defined as the ratio of the number of deaths within a given time to the number of people alive at the middle of the period, referred to some round number (1000, 10,000 100,- GENERAL DEATH RATES OF THE UNITED STATES (REGISTRATION AREA) AND CERTAIN FOREIGN COUNTRIES FOR EACH OF THE YEARS FROM 1900 TO 1914. 912 1913 1914 Fig. 130. — {Mortality Statistics, IQI5> Bur. Census.) 000) as a basis for comparison. The period commonly chosen is one year. In estimating populations for this purpose it is necessary to estimate the mid-year population, making suitable corrections with the census figures for the dates to which they have been referred. Their precision depends upon the accuracy of the population and death figures. 3i8 PRACTICAL PREVENTIVE MEDICINE They are computed as follows: A population of 60,000 has in one year 900 deaths. What is the crude death rate per 1000? Method A. 900 Method B. 60,000 900 X 1000 = 15 60,000 1000 = i5 240 220 200 180 160 140 £120 100 80 60 40 20 SPECIFIC DEATH RATES OF MALES AND FEMALES IN ORIGINAL REGISTRATION STATES 1910 FROM U.S. LIFE TABLES PREPARED BY PROF. JAMES. W. GLOVER, FOR THE BUREAU OF THE CENSUS, 1916 / f r 1 1 $ 1 9 f ? 4 /» li r* // 1 1 y6 I * .*. w^- 3^ 1 2 ] '6 J 4 5 6 J 7 & 3 9 100 Age in Years Fig. 131. — Specific death rates of males and females. (Whipple, "Vital Statis- tics," John Wiley and Sons.) Their most common use is in a comparison of the mortality in the same community in different years, or between two com- STATISTICS OF BIRTHS AND DEATHS 319 munities having similar populations. If the crude rate is em- ployed in making comparisons between two communities having similar populations, falacious conclusions will almost certainly be drawn. For this purpose special rates should be employed of which we will shortly speak (Fig. 130.) It is sometimes desirable to compute the death rates for short periods, such as weeks, months or quarters. When so com- puted these are expressed in terms of annual rates, i.e. as what the annual rate would be providing the deaths occurred through- out the year with the same frequency as during the week or month under consideration. Another type of death rates frequently computed are the so-called specific rates. These are the rates for specific or limited groups of the population, such as those of age, sex, social condition, occupation, etc. They are stated as the proportion of the number of deaths per annum in the sub-group per 1000 of the mean annual number of the population in that sub- group. The groupings of age and occupation are most com- monly employed (Fig. 131). The expression of births according to women of child bearing age may be considered a specific birth rate. They are the computations which should be em- ployed for purposes of comparison or to secure a true insight into the prevalence or incidence of different diseases. Their computation can be readily understood from the following example. Divide the number of deaths of persons whose ages lie within the age groups employed, by the number of thou- sands of persons alive in the same groups at the mid-year. Thus: TABLE XII Boston Deaths by Age Periods for 1912 Age groups Number of deaths Estimated population in each age group Specific death rate (iooo) Under 1 . . . . 1-19 20-39 40-S9 60 and over Total. . . . 2,186- i,39i- 2,017- 2,771- 3,274- 14,550 234,100 273,400 154,000 47,4oo 150 5 7 17 68 11,639 (total deaths) 724,175 (total popu- lation) 16.17 (crude) 3 2 ° PRACTICAL PREVENTIVE MEDICINE A still better method to employ for comparative purposes is the standardized or corrected death rate. This is based upon a standard or stable population, not affected appreciably by migratory factors. The Swedish census of 1890 which had 5 age groups, or the standard million of England and Wales of 1 901 with eleven age groups further subdivided according to sex, are most commonly used as a base. The standard Swed- ish population is divided per 1000 as follows: Under 1 25 •5 1-19 398 20-39 269.6 4o-59 192 3 60 and over 114 .6 The method is employed as follows: Compute the specific death rates of the several age groups of the population whose standardized death rate it is desired to obtain (Table XII). Then take the corresponding age groups in the standard popula- tion and compute the number of deaths that would have occurred in each age group at the specific death rate found to exist in the population for which the standard death rate is being computed. Add the number of deaths which it is thus found would have occurred in the age groups of the standard population. This gives the standardized rate per 1,000,000. The rate per 1,000 is secured by dividing this by 1 ,000. We may exemplify this by continuing the employment of the Boston data already given. TABLE XIII Application of Corrected Death-rate, Boston, 191 2 Age group Specific death rate Standard age distribution (Swedish) Corrected death rate Under i.. . . I-I9 20-39 40-S9 60 and over 150 5 7 17 5 X 93 X 35 X 95 X 8 X 25.54-1,000 3- 398.04-1,000 2. 269. 6-5- 1,000 1 . 192 .34-1,000 3- 114.64-1,000 7- Corrected death rate : 19.45 STATISTICS OF BIRTHS AND DEATHS 321 This is seen to be considerably higher than the crude death rate of 16.17 °f our previous computation. Their value for comparative purposes is further shown in the following table: Cambridge, Mass. Chicago Crude death rate 15.2 14-5 14-5 16.4 Standardized death rate With the employment of only the crude rate erroneous im- pressions might be drawn. Death rates are influenced by the following factors: (a) Statistical methods employed in their computation, (b) The age, sex and social composition of the population, (c) The number and size of hospitals and institutions for the care of the sick and aged within the area, (d) Migration, (e) Hygienic and sanitary conditions. (/) The birth-rate. INFANT MORTALITY The expression of infant deaths is a difficult matter. Three methods are employed and each has disadvantages. They are as follows: (a) As a ratio between the number of deaths under 1 year of age in 1 year, and the number of births within the same year, thus -p. , It is known as "Infant Mortality." Its inac- curacy lies in incomplete birth returns. (b) As a ratio between the number of deaths in the calendar year under 1 year of age and the number of children under 1 year on July 1st of the calendar year. It is really the specific death rate, thus^— ; — 7— : — . Its inaccuracy is likewise Infant population due to incomplete birth returns. (c) As a ratio between the number of deaths under 1 year and the total deaths at all ages. This ratio is subject to fluctua- tions not related to infant mortality. REFERENCES Rosenau: Preventive Medicine and Hygiene, 3rd ed., pp. 101 7-1033. Physician's Pocket Reference to the International List of Causes of Death. Bureau of the Census. 21 322 PEACTICAL PREVENTIVE MEDICINE Birth Registration: Monograph, Children's Bureau. The Federal Registration Service of the United States. Bureau of the Census. Whipple: Vital Statistics. Vital Statistics: Supplement 12, Public Health Reports. Standard Certificate of Birth and Correctionary Supplement. Standard Certificate of Death. Annual Reports on Mortality Statistics and Birth Statistics of the Census Bureau, 1900. The Accuracy of Certified Causes of Death. Reprints, 363, 440, Public Health Reports. CHAPTER XXXVII STATISTICS OF SICKNESS i. From the standpoint of public health, statistics of sickness or morbidity statistics are the vital statistics of greatest im- portance. These show the occurrence of disease and its rela- tive prevalence in different localities and at different times. This information is primarily secured by a system of report- ing cases of illness known as notification. The responsibility for making these reports is primarily placed on the practicing phy- sicians, and to a lesser extent on the householder or family head in the absence of an attending physician. Laws or regula- tions requiring these reports should specify that all real or suspected cases or carriers should be reported within 24 hours of their recognition or suspicion. Reports may be either by phone or mail, but the former method should always be confirmed in writing. As previously brought out, modern methods of disease control are based upon a prompt knowledge of how, when and where cases of preventable diseases are occurring. Consequently physicians in submitting their reports to health authorities are rendering a very important service in disease control In this country the so-called model morbidity law now furnishes the basis for most reporting of this character. While adequate penalties should be provided for failure to make the necessary reports, yet health authorities will find it advantage- ous to make reporting as easy as possible for busy practitioners. One very helpful aid in this connection is the printing of re- port blanks on post cards and keeping the physicians adequately supplied with these (Fig. 132). The communicable diseases were the first group whose reporting was generally required, and in addition we frequently find the occupational diseases in these lists and sometimes cancer and pellagra. The follow- ing considerations should govern health authorities in selecting diseases to be placed upon the reportable list: 1. The disease should be one of public health importance either from the standpoint of causing death or disability. 2. It should be a disease whose means of prevention are fully understood and which may be effectively combatted, or 323 324 PRACTICAL PREVENTIVE MEDICINE 3. One for which highly effectively prophylactic or thera- peutic agents exist. Thus cases of dog bites should be reported not because rabies spreads from man to man, but because prompt immunization will protect the person bitten from possible rabies in the biting animal. 4. If the disease is of itself trivial or unimportant, it may be indirectly of importance. Such as for example the confusion of chicken-pox with mild small-pox or German measles with scarlet fFaceofCardri ,191... (Date.) ■Dlsease.or suspected disease . .,..#..-.... iPatient's name ,age , sex.... . , color. „ Patient's_address ...... occupation . School attended or place of employment _ .. 'Number in household: Adults * * , children Probable source of infection or origin of disease ^ If disease is smallpox, type „ , number of time3 successfully vaccinated and approximate dates - If typhoid fever, scarlet fever, diphtheria, or septic sore throat, was patient, or is any member of household engaged in the production or handling of milk Address of reporting'j>hysician : '. Signature of physician 'Tot use of local health department. © o -4 ■ [Reverse of card.] g I as I Fig. 132 aj 3 s. t) B 5 Health Department, (City) (State) -Standard morbidity report. (Trask, Suppl. 12. P. II. Rep.) fever. These should therefore be reported so that a differential diagnosis may be made by experienced observers. 5. If an exotic disease, it should be one that could gain a permanent foothold if introduced. Thus yellow fever should be reportable in the gulf states where stegomyia mosquitoes abound, but no purpose is gained by placing yellow fever on the list of reportable diseases in Montana, where stegomyia is not found. Notification in order to be of maximum value must be as STATISTICS OF SICKNESS 325 complete as possible. We have already called attention to un- recognized sources of infection which must be sought out by the initiative of the health authorities. Various checks are em- ployed to indicate the degree with which physicians are dis- charging their notification duties. Thus all death certificates in which the ascribed cause is one of the reportable diseases should be compared with the morbidity report files to ascertain that the death was previously reported as a case. If not so previously reported, investigation will usually reveal that some one has been negligent. Case mortality ratios may also be used as a check. Thus from every death of typhoid reported, the morbidity files should reveal approximately ten reported cases of the disease. The reporting of the recognized cases by the physicians permits the health authorities to investigate the contacts for missed cases and carriers, and thus detect infected persons who would otherwise pass unrecognized and uncontrolled. The data secured by these reports should be immediately classified and tabulated by the health authorities so that the maximum information will be revealed. They first of all should be classified according to disease. Each case reported should be located upon a spot map of the area. Summaries of the total cases of each disease reported by days, weeks or months should be kept constantly up to date, making the necessary ad- ditions to these tables each day. Thus the health authorities can constantly keep their fingers upon the pulse of disease preva- lence and instantly recognize any epidemic in its incipiency and in addition deal effectively with endemic disease. Many health authorities in addition to the daily summaries above noted, also daily post the cases of diseases which may be milk- borne against the dealer from whom their milk was secured, and thus they can learn immediately of a milk-borne outbreak. If these reports are only used to prepare tables of figures to show past history of disease prevalence, very little actual service will result from reporting. In general we may say that the morbidity information will be put to the following uses: (a) It shows the geographical location of sources or foci of infection. . (b) Enables the health authorities, by the investigation of the cases reported, to secure epidemiological information of occur- rence, distribution and prevalence of disease ; ascertain missed cases and carriers and prevent the further spread of disease. ^ (c) Enables proper treatment to be provided for those finan- cially unable to secure it. 326 PRACTICAL PREVENTIVE MEDICINE (d) Indicates the necessary preventive measures. (e) Gives the history of a given disease for a series of years, from which the endemic index may be computed. (/) In the case of occupational diseases, it shows the location of conditions causing disease or injury. For purposes of comparison morbidity information is ex- pressed by several rates, as follows: (a) The crude morbidity rate. This is the number of cases of a given disease occurring during a year per iooo or 10,000 of the total population. This is open to the same disadvantages as crude rates in general. 1385 1890 1895 1900 1905 1910 s 6 7 / / 6 / \ / \ £ / \ 1 4 3 Z Pig. 133. — Diphtheria. Number of cases notified per annum for each death registered — Michigan — 1884 to 1910 (Trask, Suppl. 12., P. H. Rep.). (b) The specific morbidity rate. These are of a value similar to specific death rates. Diseases whose incidence is limited to certain age groups should also be expressed in rates of the number of cases per iooo persons in the population of that age or class. (c) Fatality rates. These may be expressed as the number of deaths per ioo cases or as the number of cases to each death. They are the same as the case mortality ratios previously noted. Owing to failures to report all cases they are usually too high (Figs. 133, 134) For areas of small size with small or moderate populations, STATISTICS OF SICKNESS 327 small charts will enable the health authorities to keep in touch with the daily or weekly incidence of communicable diseases and detect epidemics in their incipiency. On the other hand, where a large number of geographical units must be supervised a more rapid method of ascertaining fluctuations of disease prevalence from the normal or endemic prevalence is afforded by comparison of the monthly summaries with the so-called endemic index of a disease for the area under consideration. This is the average monthly incidence of the reported cases of the disease in a given geographical unit, exclusive of cases rising 1885 1890 1895 1900 190S 1910 ) fc So " / - / / / 15 1 - 10 . — 1 -. •f , Fig. 134. — Diphtheria — Fatality rate (number of deaths registered per annum) per- 100 notified cases) — Michigan — 1884 to 1910 (Trask, Suppl. 12., P. H. Rep.). in epidemics. Such standards of course require occasional revision. By their employment the beginning of an epidemic can be promptly noted. REFERENCES Public Health Administration: Its Dependence Upon Reports of Cases of Sickness. Reprint 109, Public Health Reports. A Model State Law for Morbidity Reports. Reprint 133, Public Health Reports. Morbidity Reports: Their Importance to the Local Health Officer and His Work. Reprint 153, Public Health Reports. The Massachusetts Endemic Index. Reprint 442, Public Health Reports. Industrial Morbidity Statistics. Reprint 484, Public Health Reports. SECTION VIII PUBLIC HEALTH CHAPTER XXXVIII PUBLIC HEALTH ADMINISTRATION Public health administration in the United States is a func- tion of the federal, state and local governments. THE FEDERAL AGENCIES IN PUBLIC HEALTH WORK The principal agency in this field is the Bureau of the Public Health Service of the Treasury Department, which has developed out of the old Marine Hospital Service. Other bureaus whose activities are related to public health are the following : (a) Census Bureau, Department of Commerce. The Cen- sus; Statistics of Births and Deaths. (b) Children's Bureau, Department of Labor. Child Hygi- ene and Maternal Hygiene. (c) Bureau of Animal Industry, Department of Agriculture. Federal Meat Inspection. (d) Bureau of Chemistry, Department of Agriculture. Food Inspection. (e) Bureau of Biological Survey, Department of Agriculture. Coyote eradication (rabies). (/) Department of Labor. Industrial Hygiene. (g) Bureau of Mines, Department of Interior. Industrial Hygiene in the mining industries. (h) Bureau of Education, Department of the Interior. School hygiene and sanitation. The activities of the Public Health Service are more diverse, including control over interstate and international quarantine, supervision of the manufacture of biological products for hu- man use, and inspection of immigrants. It also co-operates with States and Local Governments in epidemic control upon the invitation of the latter, and undertakes demonstrations of 328 PUBLIC HEALTH ADMINISTRATION 329 practical sanitation, and conducts field and laboratory inves- tigation into the public health problems of the United States. It can thus be seen that there has been no systematic or co- ordinated plan in the development of our federal public health work. Effective work is being done, but there is much over- lapping; departmental rivalry cannot stimulate economical or efficient work. There is great need for a co-ordination of all existing federal agencies, which probably can best be accom- plished by their segregation into a single Public Health Department. Lack of more definite federal control is due to FlG- 135- — A muster of steerage passengers. The boarding launch standing by ready for orders. (Cofer, U. S. P. H. S.) the fact that all authority that the federal government possesses has been delegated by the individual states. The present trend of national policies seems to be towards a stronger central government. Where this will end, or what public health ac- complishments will results cannot be accurately forecasted. Before going further it might be well to briefly speak of the administration of maritime quarantine. All vessels either domestic or foreign which contemplate touching at an American port from abroad, are required to secure from the American Consul a document known as a bill of health. This is a state- ment of the health conditions aboard ship during her stay in 330 PRACTICAL PREVENTIVE MEDICINE foreign ports, the number of passengers discharged, embarked, etc. Upon her arrival at an American port, the vessel first drops anchor at the quarantine station, where the boarding officer of the public health service receives the Bill of Health and examines the passengers, crew and vessel (Fig. 135). If no quarantinable diseases are found on board and the vessel has not come from a plague or yellow fever port, the boarding officer discharges the vessel from quarantine by the issuance of a certificate known as pratique. She is then free to proceed to her designated wharf or moorings. On the other hand, if any of the quarantinable diseases (cholera, yellow fever, plague, typhus, small-pox or leprosy) are found the passengers and crew are detained in quarantine for the period designated in the regu- lations, while their baggage and effects are fumigated. If the vessel comes from a plague or yellow fever port, the vessel is fumigated with sulphur dioxide or hydrocyanic acid to kill mosquitoes or rats. After these requirements are met pratique is granted. STATE PUBLIC HEALTH ADMINISTRATION Efficiency of organization and administration varies in differ- ent states, depending on their degree of progressiveness, freedom from political interference and the appropriations available. In Massachusetts, New York, Minnesota and a few others the organizations are highly efficient and developed along modern lines. In a few the state organizations practically exist on paper. The organizations in the remainder are manifestly inadequate. In these the state organization has evidently been particularly designed to exercise a loose supervision over, or an advisory capacity toward the local authorities, without possess- ing organization, staff, authority or appropriation enough to make the work efficient. The different states really possess broad authority in matters pertaining to the public health under their constitutional police powers. A great impediment to the application of modern health methods is the fact that existing legislation is fre- quently based upon antiquated and erroneous ideas of pre- ventable diseases and hence is of little value. The administration of existing statutes in the different states is accomplished through the agency of State Boards or Depart- ments of Health. In the former authority is centered in the Board and affairs move slowly. In the latter the head of the PUBLIC HEALTH ADMINISTRATION 33 1 department possesses the executive authority and prompt action is possible. An unfortunate phase of this situation is the fact that many of the appointments to these executive positions are not based upon training, experience, or other qualifications for public health work, but are given as rewards for political service. There is much opportunity for improvement in state health administration over the United States. LOCAL HEALTH ADMINISTRATION The units of local administration vary in different states, from counties to townships, cities and towns, the latter opera- ting upon their charter authorizations. Authority is usually vested in a board of health, whose composition may be either of laymen or physicians, either elected or appointed. Their authority is delegated from the state. In operation it is usual to find that the administration of these local units is inefficient as well as inadequate. Consequently definite policies for the improvement of the public health or local sanitation based upon actual local needs are not formulated, and little or nothing is done to eradicate or reduce the preventable diseases of local importance. This difficulty is usually due to a popular apathy arising through ignorance of the importance of health matters and what may be done to remedy the evils. Consequently the local health administration is frequently in the hands of incom- petent laymen or part time physicians, whose only qualifications are based upon proper political affiliations. At present, de- fective local health organization and administration is the weakest spot in public health protection. The following may be suggested as remedies for this state of affairs : (a) Popular education, i.e., public health propaganda. Despite such efforts the public conscience can sometimes only be stimulated to the point where improvement is demanded as a result of a disastrous epidemic. (b) Whole time public health officials with special pro- fessional or technical qualifications for the work. Success in this field requires the possession of an abundance of tact and diplomacy. Properly qualified whole time men should receive adequate remuneration. (c) Adequate ordinance or regulations wisely and effectively enforced. 332 PRACTICAL PREVENTIVE MEDICINE HEALTH OFFICERS Health officers are usually the executive officers of the local board of health, whose duty it is to enforce the existing , local regulations. Most commonly we find they have been recruited from the ranks of the local medical profession and give part time service. Their tenure of office is usually brief and their remuneration likewise slender. Public health work is now a distinct field, requiring special professional training. Medical training is of distinct value for public health work, probably more than that of any other profession if considered alone, but we must recognize that in itself it does not adequately qualify an individual for this field of work. An appreciation of the importance of public health work is is rapidly spreading in the United States to-day-. As a conse- quence we shall rapidly see the old order of incompetency we have sketched pass away. The new order will demand im- provement and require trained men to direct the work. Un- usual opportunities now present themselves to trained men in this field. HEALTH LAWS AND REGULATIONS Drafts of proposed health legislation had best be carefully scanned by competent lawyers before enactment. Only laws that are capable of enforcement and whose constitutionality is above attack are of value. They must not exceed in their scope the authority delegated by the state to local administra- tive units. It must also be recognized that ability to secure their successful enforcement, particularly in those cases which require jury trials, depends upon the existence of a popular sentiment appreciating their necessity. Proper enacting and penalizing clauses should not be overlooked. NUISANCES Nuisances are what the name implies, both to the laymen and the health officer. Most conditions belonging to this category are not of public health importance, but a health officer may be bothered and annoyed by questions properly referable to police and peace officers for solution or abatement. From a public health standpoint the chief nuisances are grouped as follows: conditions favoring mosquito breeding (ponds, ditches, swamps, etc.,) rat harbourage (dumps, dilapidated buildings); fly breeding (manure piles, garbage); and excreta disposal PUBLIC HEALTH ADMINISTRATION 333 (dilapidated privies, full vaults etc.) From the standpoint of the public anything which is offensive to the senses constitutes a nuisance and many are the basis of legislation. A better definition is "The use of one's property in such a way as to injure the rights of others or to inflict damages." The abate- ment of nuisances may be accomplished through four different lines of procedure: (a) by criminal action, (b) by injunction, (c) by suits for damages (private suit) and (d) by abatement under statutory powers. PHYSICIAN'S DUTIES IN PUBLIC HEALTH WORK ^ A physician's responsibilities in public health work are of two kinds, his professional obligations which include the relationship between himself and his patients, and second, his legal obliga- tions through responsibilities conferred by law. ^ The first group particularly includes the following responsi- bilities : (a) Prompt and accurate diagnosis. (b) Efficient treatment. (c) Education of the patient and his family in simple hygiene and sanitation, and the enlistment of their co-operation in the cheerful and careful discharge of measures to prevent the further spread of a disease. (d) Co-operation with the legal heaith authorities. His legal obligations include: (a) Birth registration. (b) Signing death certificates. (c) Morbidity reporting. PUBLIC HEALTH EDUCATION Statutory enactments in the field of public health are not a panacea. Their purpose should be to secure uniformity of procedure, to provide means of coercing those who persist in trespassing on the rights of others and to centralize and define authority. Popular support is only given as the people see the necessity for protection and feel that the results desired can be secured. Much more can be accomplished by the education of the public in matters of hygiene and sanitation, which will render compulsory enforcement unnecessary. It is a slow process and must be carefully developed. Avenues of instruction available 334 PRACTICAL PREVENTIVE MEDICINE are through the press, the movies, pamphlets and circulars, lectures, special conferences and exhibits, and instruction in secondary schools. All information imparted should be funda- mentally sound and one should avoid making dogmatic state- ments about debated points or unsettled questions. It is better to proceed slowly and safely than to later find it neces- sary to retract statements. Of the printed channels of com- munication the press is probably the best, since a large audience is reached. Articles for this purpose should be brief, to the point and written in simple language. Effective publicity work is quite an art and should receive considerable care and attention. In the past the field of public health has been chiefly charac- terized by the growth and developement of the principles of sanitation, i.e., of the care and attention that must be expended upon the environment of the human race. The greatest achievements have been realized in the control of the excreta and insect borne infective agents in those communities where their application has been undertaken. One is probably not greatly in error in declaring that in those communities the culti- vation of this field has very nearly yielded its maximum fruitage. By this we do not intimate that a decline in the rated value or esteem of sanitation is to be expected, but that the diseases which may be considered at present to be a more or less un- solved problem in preventive medicine will be conquered by achievements in the field of personal hygiene. Needless to say the cultivation of this field may not be expected to yield as early a harvest as has sanitation. An enlightened policy on the part of public health officials, together with administration by trained sanitarians, in other words the activities of a few individuals, can secure all the benefits arHng from adequate sanitation to a community, without the very active co-opera- tion of the individual citizen. On the other hand, personal hygiene can only be effectively promoted through the aroused interest and education of each individual in the entire popula- tion concerned. This stage will arrive slowly and it may require the span of one or two generations before hygiene attains the position occupied by sanitation at the present time. PHILANTHROPIC AGENCIES An account of public health administration would not be complete without calling attention to the assistance given by private munificence. One of the most notable examples is that PUBLIC HEALTH ADMINISTRATION 335 offered by the Rockerfeller Foundation through the Inter- national Health Board. This organization is made possible by the income from funds provided by John D. Rockefeller and its work was originally directed at the world wide control of hookworm disease. This has later been extended to yellow fever and will probably later include malaria. This organiza- tion has not entered the field independently. Thus in the Southern United States it has co-operated with the different state boards of health, furnishing competent directors and a quota of the funds. The results that are following this work are of inestimable value. Another philanthropy working along somewhat different lines is the Russell Sage Foundation. PUBLIC HEALTH NURSING Successful work in disease control and prevention largely depends upon the degree of attention paid the individual human units of an area. The realization of this responsibility pri- marily arose in the out-clinic departments of some of the larger eastern hopitals. It was long realized that many patients ceased attendance at the clinics before being fully benefited by their treatment, or that bed patients following their discharge in a condition of distinct improvement, returned to home sur- roundings so unfavorable that the improvement laboriously achieved by the hospital was soon lost. Efforts were made to improve these conditions through the frequent visitation of patients in their homes, by urging the continuation of their clinic attendance, by instructing the responsible members of the family in their proper feeding and care, by providing the assistance of charitable agencies where such assistance was required. As a consequence the benefits of the hospitals have been greatly extended and their accomplishments afforded a greater degree of permanency. This type of service has been adopted by various health departments, for the most part se- curing the services of graduate nurses for this purpose. We have previously called attention to public health nursing in connection with maternity and child welfare clinics. A similar service can be rendered in the control of communicable diseases, through proper follow up care of patients discharged from isola- tion. Another variation of this type of service is afforded by the so-called visiting nurse, who makes periodical visits to the homes of those unable to provide hospital facilities or trained nursing, or where free hospital beds are not available, re- gardless of the character of the patient's illness. Instruction 336 PRACTICAL PREVENTIVE MEDICINE is given the responsible members of the household in the proper feeding and care of the patient and in the execution of the physician's directions. The daily visits are continued as long as necessary to insure a continuation of the lessons given and to give further instruction. Thus in the public health nurse there has developed a distinct type in the social worker. REFERENCES Maritime Quarantine. Public Health Bulletin 34, U.S.P.H.S. Chapin: A report on State Public Health Work based on a Survey of State Boards of Health. American Medical Association. Interstate Quarantine Regulations of the United States. U.S.P.H.S. What Social Workers Should Know About Their Own Communities. Pub. 7, Russel Sage Foundation. Hemenway: Legal Aspects of Public Administration. Gardner: Public Health Nursing. State and Insular Health Authorities, 1918. Reprint 488, Public Health Reports. Public Health Administration in Minnesota. Reprint 233, Public Health Reports. Cooperative Public Health Administraton. Reprint 222, Public Health Reports. Federal Public Health Administration. Reprint 112, Public Health Reports. The Practicing Physician: His Relation to Public Health Administration. Reprint 280 Public Health Reports. Directory of City Health Officers, 191 7. Reprint 416, Public Health Reports. Public Health Laboratory Specimens, their preparation and shipment. Reprint 438, Public Health Reports. Overton and Denno: "The Health Officer." Chapters, I, II, III, IV, VI, VII, VIII, IX, XI, XII, XXXVI. INDEX Accessory food factors, 233 Accidents, industrial, factors in pro- duction, 244 Activation treatment of sewage, 112 Acute gastro-enteritis as a cause of infant mortality, 268 infections as a cause of infant mor- tality, 269 respirator}'- infections as a cause of infant mortality, 269 Adenoids, 277 Administration, public health, federal, 328 local, 331 state, 330 Adulterations of food, 225 of milk, 150-225 Aeration of water, 131 Air, amount of, necessary, 286 bad or injurious, 283 chemical composition, 282 cold, damp, 284 heating and ventilation, 283 humidity of, 283 odors in, 283 pressure as an occupational hazard, 242 relation of man to, 284 variations of, 282 warm, dry, 284 moist, 284 Albinism, 263 Alcoholism, 234 Alga? in water, 127 Algal destruction, 131 Alummosis, 253 Amoebic dysentery, 70 Animals as sources of infection, 203 22 337 Anopheline mosquitoes, 188 adult, 189 resting, 190 egg, 189 larvae, 190 pupEe, 190 Anthrax, communicability, period of, 215 disinfection in, 215 entrance of, 215 exit of infective agent, 215 general measures against, 215 immunization of cattle, 215 of man, 215 infective agent of, 215 incubation period of, 215 isolation, 215 methods of control, 215 occupational, 216 quarantine, 215 route of transmission, 215 source of infection, 215 Anthracosis, 253 Antitoxin, diphtheria, employment of, 60 tetanus, employment of, 218 Arithmetical method of population estimation, 304 Arsenic as an industrial poison, 249- 250 Artificial feeding of infants, 271 Aseptic nursing, technique of, 77 Aspiration in ventilation, 286 Aural hygiene, 276 Bacteria in milk, sources of, 150 in certified milk, 158 in inspected milk, 160 in water, 128 Bacterial standards for water, 128 33* INDEX Bathing, hygiene of, 292 Baths, kinds of, 293 Bed-bug, 199-201 Bends, 242 Benzin as an industrial poison, 249- 251 Benzol as an industrial poison, 249 Beri-beri, definition of, 230 distribution, 230 etiology of: past ideas, 231 present ideas, 231 incidence of, 231 prevention of, 233 public protection, 234 Bills of health, 329 Biological transmission of infective agents by insects, 1S0 Birth, accidents at, as a cause of in- fant mortality, 267 certificate, 313 rates, 312 factors influencing, 314 records, value of, 312 registration, 312 statistics, 312 Black boards, 279 Blindness, preventable, 46 Boarding of babies, 270 Body louse, destruction of, 187 Boiling as a means of disinfection, 95-98 Botulism, 178 Brass founders ague, 251-252 Breast feeding, 271 Breathing cone, 286 zone, 286 Bubonic plague, 203-205 Burial permits, 314 Byssinosis, 253 Canned food, 178 Carbon bisulphid as an insecticide, 187 dioxid of the atmosphere, 284 Caries, dental, 277 Carriers, 26 classification of, 26 convalescent, examples of, 28 Carriers, healthy, examples of, 27 incubatory, examples of, 27 Cases, abortive, 26 atypical, 26 examples of, 27 latent, 27 missed, 26 typical, 26 Cause of death, statement on death certificate, 314 Census, 301 enumerations, errors in, 302 Ceratophyllus fasciatus, 204 Cesspools, 120 leaching, 122 vaulted, 122 Chalcicosis, 253 Charities, milk, 273 Chemical closets, 117 Chicken-pox communicability, period of, 51 entrance of, 51 exit of infection, 51 incubation period, 51 infective agent, 50 methods of control, 5r route of transmission, 51 source of infection, 51 Childhood, communicable diseases of, 275 definition of, 275 Children's diseases and contact, 37 hygiene of, 275 Chlorinated lime as a disinfectant, 98 Chlorine as a disinfectant of water, 138-146 in water, 127 Cholera, Asiatic, 69 communicability, period of, 69 disinfection, 69 entrance of, 69 epidemic measures, 70 exit of infective agent, 69 immunization, artificial, 69 incubation period, 69 infective agent, 69 isolation, 69 INDEX 339 Cholera, Asiatic, methods of control, 69 quarantine, 69 routes of transmission, 69 source of infection, 69 Cimex lectularius, 199, 201, 204 Cistern, protection of, 145, 148 Class-room, cleaning of, 280 Cleanliness, personal, education of public in, 92 facilities for, 289 Climate, relation of clothing to, 294 Closet, indoor, 298 Clothing, hygiene of, 293 Coagulation in treatment of water, 133 Color blindness, 264 of clothing, 294 Common personal articles, 34 Communicability, period of, in an- thrax, 215 chicken-pox, 51 cholera, 69 dengue, 197 diphtheria, 59 dysentery, amoebic, 71 bacillary, 71 german measles, 54 gonorrhoea, 43 influenza, 57 leprosy, 66 malaria, 191 measles, 51 meningitis, 61 mumps, 52 plague, 63 poliomyelitis, 63 pneumonia, 63 poliomyelitis, 63 rabies, 212 relapsing fever, 200 scarlet fever, 55 septic sore throat, 56 small-pox, 48 spotted fever, rocky mt., 210 syphilis, 41 tetanus, 217 tuberculosis, 64 typhoid, 67 Communicability, period of, typhus fever, 197 uncinariasis, 72 whooping cough, 56 yellow fever, 196 Communicable diseases, definition of, 24 Confinements, proportion at home and at hospital, 257 Congenital defects as a cause of in- fant mortality, 267 Conjunctivitis, acute, 276 Contact, beds, 115 direct, diseases transmitted solely by, 34 importance of, with different infective agents, 34 definition of, ^3 density of population and, 36 diseases and seasons, 39 frequently transmitted by, 35 usually transmitted by, 35 effect of over-crowding on, 37 epidemics, character of, 39 importance of with different types of sources of infection, 36 indirect, 34 means of, ^^ route of exit from the body and, 35 transmission, features characteristic of, 36 Contagious diseases, definition of, 24 Cooked food, 178 Cotton, value as a fabric for clothing, 294 Cow-pox, 203 Crede's prophylaxis for ophthalmia neonatorum, 46 Cyanide as an insecticide, 186 Dairy inspection, score card for, 161 products as routes of infection, 163 Deaf mutism, 263 Death certificate, 314-315 errors in, 314 rates, 317 corrected, 320 34° INDEX Death rates, factors influencing, 321 specific, 319 standardized, 320 records, value of, 315 Defects, orthopedic, 275 Degenerate, 264 De-limitation of plague focus, 207 De-lousing equipment, use of, 199-200 Demography, definition of, 301 Dengue, communicability, period of, 197 disinfection, 197 entrance of infective agent, 197 exit of infective agent, 197 immunization, 197 incubation period of, 197 infective agent, 196 isolation, 197 methods of control, 197 quarantine, 197 route of transmission, 197 source of infection, 196 Dental hygiene, 277 Dermacentor venustus, 210-21 1 Dessication as a disinfectant, 95 Determiner, 261 Diet, insufficient, 229 representation of food elements in, 224 unbalanced, 229 Digestion tanks, two story, no Diphtheria, antitoxin, administration of, 59 communicability, period of, 59 disinfection, 61 entrance of, 59 exit of infective agents, 59 general measures, 61 immunization, artificial, 59 incubation period, 59 infective agent, 59 isolation, 59 methods of control, 59 quarantine, 61 route of transmission, 59 Schick test, 60 source of infection, 59 Diptheria, toxin-antitoxin mixtures, 60 Dirt in milk, 152 Dipping domestic animals, 210 Disease control, principles of, 74' Diseases, preventable, classes of, 17- 18 Dishes, sterilization of, 227 Disinfectants, action, manner of, 94 chemical, 95 definition of, 94 desiccation as a, 95 efficiency of, 97 external, 94 gases as, 95 heat as a, 95 internal, 94 light as a, 95 physical, 94 properties of an ideal, 96 solutions as, 95 standardization of, 95 suspension as, 95 Disinfection concommittant, 79 concurrent, 79 definition of, 94 of water, 138 technique of, concurrent, 97 terminal, 79 Dogs, muzzling of, 214 Domestic excreta disposal, 116 results of, 143 sanitation, 295 water supplies, 145 emergency protection of, 146 Dominant characteristics, 261 Dosage of infective agents, 30 Drainage, anti-mosquito, 191 area of operations, 192 Droplet infection, 33 Duplex combinations of determiners, 263 Dusts as an occupational hazard, 238- 252 remedies for, 253 Dwellings, construction of, 245 definition of, 307 location of, 295 INDEX 341 Dysentery, amoebic, communicability, period of, 71 disinfection, 71 entrance of, 71 exit of, 71 general measures, 71 immunization, artificial, 71 incubation period of, 71 infective agent, 70 isolation, 71 methods of control, 71 quarantine, 71 route of transmission, 70 source of infection, 70 bacillary, communicability, period of, 71 disinfection, 72 entrance of, 71 exit of, 71 general measures, 72 immunization, artificial, 71 incubation period of, 71 infective agent, 71 isolation, 71 methods of control, 71 quarantine, 72 route of transmission, 71 source of infection, 71 Eating houses, 227 Education, public health, of the public, 333 Electrical hazards, 242 Emmigration, 303 Endemic, definition of, 25 index, 327 Enteric group, 67 Epidemic, definition of, 25 Epidemics, 168 contact, 39 food borne, 178 milk borne, 172, 173 water borne, 125 Epidemiological investigation, 86 analysis of data, 91 data required, 86 emergency epidemiology, 92 Epidemiological investigation, plot- ting of cases, 91 routine epidemiology, 92 Epidemiology, definition of, 24 Epizootic, definition of, 25 Eucalyptus, 192 Eugenics, 265 Excreta, disposal, domestic, 298 modern methods of disposal, 104 relationship to health, 104 Exercise, effects of, 289 influence of, on metabolism, 288 on arterial pressure, 289 on digestive processes, 289 on flow of blood and lymph, 288 on heart, 288 on heat production and regu- lation, 289 on muscular tissues, 289 on perspiration, 289 on respiration, 289 on slumber, 289 Explosions, mine, 241 Explosives, permissible, 241 Eye strain, 276 Fatigue, 238-290 effect of excitement on, 291 industrial, relation to accidents, 291 muscle, 290 neurone, 290 receptor, 290 Federal agencies in public health work, 328 Feeble mindedness, 264 Feeding, artificial, of infants, 271 breast, of infants, 271 Felix-Weil reaction, 197 Filling, anti-mosquito, 191 Filters, rapid sand, 136 roughing, 112 slow sand, 135 trickling, 115 Filtration, intermittent sand, of sew- age, 115 of water, 135 342 INDEX Fingers as a means of contact transfer, 33 Fire hazards, 242 in mining, 241 Fish as an anti-mosquito agent, 192 Fleas as a vector, 204 destruction of, 205 Focal infection, 221 Fo mites, 32 distinction from indirect contact, 32 Food handling, hygiene of, 227 accessory factors, 233 adulteration of, 225 animal, 225 as a route of infection, 175 caloric value of, 223 definition of, 223 determination of suitability, 223 elementary, 223 epidemics, 178 origin of, 225 preservation of, 226 poisonous, 230 proportion of elements of, in daily diet, 224 refrigeration of, in the kitchen, 300 relation to health, 229 requirements, 224 production and retail, 223 retail of, 226 use by body, 223 utilization of elements of, in daily diet, 224 vegetable, 225 Foot and mouth disease, 167-203 Formaldehyde as a fumigant, 98 Formalin, solution for disinfection, 97 Fracastorius, 21 Friedreich's ataxia, 264 Fumigants, employment of, 98 Fumigation, preparation for, 95-102 Fungi, lower animals as sources of, 203 Gambusia, 192 Ganister disease, 253 Garbage, disposal, in the kitchen, 300 Geometrical method of population estimation, 305 German measles, communicability period of, 54 disinfection, 54 entrance of, 54 exit of infective agent, 54 incubation period, 54 infective agent, 54 isolation, 54 methods of control, 54 quarantine, 54 route of transmission, 54 source of infection, 203 Glanders, 203 Gonorrhoea communicability, period of, 43 disinfection, 43 entrance of infective agent, 43 exit of infective agent, 42 general measures, 43 immunization, 43 incubation period, 43 infective agent, 42 isolation, 43 methods of control, 43 route of transmission, 42 source of infection, 42 Haffkine's vaccine, 205 Halls, management of ventilation, 287 Hands as a means of contact transfer, 33 Hardness of water, 127 permanent, 127 temporary, 127 Hazards, occupational, classified, 236 Health officers, 332 Hearing, defective, 276 Heat, as a cause of infant mortality, 273 as a disinfectant, 95 excessive, as an occupational haz- ard, 238 losses from the body, 283 Heating, artificial, bodily require- ments, 285 INDEX 343 Heating, artificial, means for, 285 domestic, 297 of schools, 279 Hemophilia, 264 Hereditary diseases, 260 Heredity, definition of, 260 Hides, as a route of infection for anthrax, 215 disinfection of, 217 Holmes, O. W., 22-256 Home environment, unsanitary, 237 Hookworm disease, see also Uncinaria ■ sis, 72 House fly borne epidemics, 184 control of, 185 Humidity, effect on the bodily comfort, 283 extremes of, 238 Huntington's chorea, 263 Hybrids, 261 Hydrocyanic acid gas as an insecti- cide, 186 Hygiene, definition of, 17 personal, 288 Illumination, 296 Imhoff tanks, no Immigration, 303 Immunization, artificial, as a defensive weapon, 222 in prophylaxis of anthrax, 215 of chicken pox, 51 of cholera, 69 of diphtheria, 59-60 of dysentery, amoebic, 71 bacillary, 71 of dengue, 197 of german measles, 54 of gonorrhoea, 43 of influenza, 57 of leprosy, 66 of malaria, 191 of measles, 52 of meningitis, 62 of mumps, 53 of plague, 205 of pneumonia, 64 Immunization, artificial, in prophylaxis of poliomyelitis, 63 of rabies, 212 of relapsing fever, 200 of scarlet fever, 55 of septic sore throat, 56 of small pox, 49 of spotted fever, Rocky. Mt, 210 of syphilis, 42 of tetanus, 217 of tuberculosis, 65 of typhoid, 68 of Uncinariasis, 73 of whooping cough, 57 of yellow fever, 196 Inactivity, 238 Incubation period, definition of, 24 extrinsic, 181 in anthrax, 215 in chicken pox, 51 in cholera, 69 in diphtheria, 59 in dysentery, amoebic, 71 bacillary, 71 in dengue, 197 in german measles, 51 in gonorrhoce, 43 in influenza, 57 in leprosy, 66 in malaria, 189 in measles, 51 in meningitis, 61 in mumps, 52 in plague, 204 in pneumonia, 63 in poliomyelitis, 62 in rabies, 212 in relapsing fever, 199 in scarlet fever, 55 in septic sore throat, 56 in small pox, 48 in spotted fever, Rocky, Mt., 210 in syphilis, 41 in tetanus, 217 in tuberculosis, 64 in typhoid, 67 in typhus fever, 197 344 INDEX Incubation period, in uncinariasis, 72 in whooping cough, 56 in yellow fever, 195 Infancy, definition of, 267 hygiene of, 267 mortality during, 267 Infants, institutional care of, 270 mortality, causes of, 267 as a sanitary index, 270 comparative, 268-269 methods of expressing, 321 Infections, industrial, 239 Infectious disease, definition of, 24 Infective agents, extra corporeal ex- istence of, 50 portals of entrance, 30 routes of exit from body, 28 Influenza, communicability, period of, 57 disinfection, 58 entrance of, 57 exit of infective agent, 57 general measures, 58 immunization, artificial, 57 incubation period, 57 infective agent, 57 isolation, 57 methods of control, 57 routes of transmission, 57 source of infection, 57 Insecticides, 185 carbon bisulphid as, 187 hydrocyanic acid gas as, 185 physical agencies, 187 pyrethrum, 187 sulphur dioxid as, 185 use of, 185 Irrigation, broad, of sewage, 115 sub-surface of sewage, 114 Isolation, conditions necessary for, 75 definition of, 74 hospitals, cubicle type, 76 pavillion type, 76 success of, 80 termination of, 80 Jenner, 22 Kircher, 22 Kitchen, sanitation of, 299 Koch, Robert, 23 Larvacide of Darling, 192 Law, public health, 332 Lead poisoning, channels of entrance, 247 from water, 125 industries in which encountered, 245 remedies, 249 symptomatology, 249 Leeuwenhoek, van, 22 Leprosy communicability, period of, 66 disinfection, 66 exit of infective agent, 65 general measures, 66 incubation period, 66 infective agent, 66 isolation, 66 methods of control, 66 routes of transmission, 66 source of infection, 65 Leptospira icteroides, 195 Light as a disinfectant, 95 Lighting as an occupational hazard, 237 of dwellings, 296 of schools, 278 Lime, chlorinated, solution for disin- fection, 98 unslaked, solution for disinfection, 98 Liquor cresolis compositus, solution for disinfection, 98 Local public health administration, 311 Loemopsylla cheopis, 204 Machinery as an occupational haz- ard, 240 guarding of, 240 Malaria, communicability, period of, 191 control in rural areas, 195 disinfection, 191 INDEX 345 Malaria, effect of temperature, on par- asites in insects, 181 entrance of infective agent, 188 exit of infective agent, 188 general measures, 191 immunization, 191 incubation period, 189 infective agents of, 188 isolation, 191 methods of control, 189 mosquito control, 191 quarantine, 191 quinine prophylaxis, 191 route of transmission, 188 source of infection, 188 sterilization of gamete carriers, 191 Malta fever, 168, 203 Manson, Patrick, 22 Manure in milk, 152 Maritime quarantine, 329 Masks, 78 Maternity clinics, 258 Measles communicability, period of, 51 disinfection, 52 entrance of, 51 exit of infective agent, 51 general measures, 52 infective agent, 51 incubation period, 51 isolation, 52 methods of control, 52 quarantine, 52 route of transmission, 51 source of infection, 51 Meat, animal parasitism of, 176 diseases transmitted by, 176 inspection of, 175 poisoning, 176 unsuited for food, 175 Mechanical transmission of infective agents by insects, 182 Mendelian inheritance, 260 ratio, 261 Meningitis, meningococcic, (cerebro- spinal), communicability, period of, 61 disinfection, 62 Meningitis, meningococcic, entrance of, 61 exit of infective agent, 61 general measures, 62 immunization, 62 incubation period, 61 infective agent, 61 isolation, 62 methods of control, 62 quarantine, 62 routes of transmission, 61 source of infection, 61 Mercury as an industrial poison, 249 Methods of control of anthrax, 215 of chicken pox, 51 of cholera, 69 of dengue, 197 of diphtheria, 59 of dysentery amoebic, 71 bacillary, 71 of german measles, 54 of gonorrhoea, 43 of influenza, 57 of leprosy, 66 of malaria, 191 of measles, 52 of meningitis, 62 of mumps, 52 of plague, 205 of pneumonia, 63 of poliomyelitis, 63 of rabies, 212 of relapsing fever, 200 of scarlet fever, 55 of septic sore throat, 56 of small pox, 48 of spotted fever, Rocky. Mt., 210 of syphilis, 41 of tetanus, 217 of tuberculosis, 65 of typhoid, 67 of typhus fever, 197 of uncinariasis, 73 of whooping cough, 57 of yellow fever, 196 Micro-organisms, portals of entrance, 29 route of exit from body, 28 346 INDEX Midwives, relation to puerperal septi- cemia, 257 Mining and quarrying, hazards of, 241 Milk, as food, 149 as route of infection, 167 care of, in the home, 165 certified, 157 classification of, 153-157 development of pathogenic bac- teria, 168- 171 dirt, gross, in, 152 for infant feeding, 271 germicidal property of, 167 inspected, 160 market, r6o micro-organisms in, 150 pasteurization of, 154 raw milk, 153 relationship to health and disease, 149 source of pathogenic organisms in, 167-171 sophistication of, 150 sources of, 151 production of, 151 temperature of storage, 153 with relation to anthrax, 216 Milking utensils, 152 Mills-Reincke phenomenon, 144 Minnow, top, 192 Model morbidity law, 323 Montague, Lady Mary Wortley, 22 Morbidity rates, 326 reporting, checks on completeness of, 325 physicians duties in, 83 reciprocal notification, 85 reportable diseases, list of, 84 requirements for reporting, 84- 323 reports, use of, by health authori- ties, 325 statistics, 323 Mortality statistics, 314, see also Deaths, 314 Mosaic law, 21 Mosquitoes, destruction of adults, 194 of breeding places, 191-196 oflarvas, 192 exclusion of adults, 194 in dengue, 197 in malaria, 188 in yellow fever, 196 Mouth spray, 33 Mumps, communicability, period of, 52 disinfection, 53 entrance of infective agent, 52 exit of infective agent, 52 incubation period, 52 infective agent, 52 isolation, 52 methods of control, 52 quarantine, 53 route of transmission, 52 source of infection, 52 Muzzling of dogs, 214 Natural immunity, 265 Negri bodies, 212 Nitrogenous compounds in water, 127 Nose, hygiene of, 277 Notification, 323 Nuisances, 332 Nurses, visiting, 273 Nursing, public health, 335 Nutritional deficiencies, 277 disturbances as a cause of infant mortality, 268 Obstetrical care for rural women, 259 Occupational anthrax, control of, 216 hazards, classified, 236 Ocular hygiene, 276 Odors, as a cause of bad air, 283 Oiling as an anti-mosquito measure, 192 Ophthalmia neonatorum, 46 Crede's prophylaxis of, 46 Orthopedic defects, 275 INDEX 347 Ova, destruction of helminth, 98 Overcrowding of dwellings, 297 Oxygen, dissolved in water, 107 Oysters, 176 Pandemic, definition of, 25 Paratyphoid fever, 67 Pasteur, Louis, 22 Pasteur treatment, 213 Pasteurization of milk, against milk- borne tuberculosis, 170 effects of, 155 on typhoid, 171 flash method, 154 holding method, 154 in-bottle method, 155 in the home, 165 storage of, 157 temperature of, 155-160 time of, 155-160 Pediculus vestimenti, 197-198 Pellagra, definition of, 230 distribution of, 230 etiology of: past ideas, 231 present ideas, 231 incidence of, 231 prevention of, 233 public protection, 234 Perflation in ventilation, 286 Personal hygiene, 288 Phenol solution for disinfection, 98 Philanthropic agencies, 334 Plague communicability, period of, 204 disinfection, 205 entrance of infective agent, 204 exit of infective agent, 204 general measures, 205 immunization, artificial, 205 incubation period, 204 infective agent, 203 isolation, 205 methods of control, 205 quarantine, 205 route of transmission, 204 source of infection, 203 Plenciz, 22 Plenum system of ventilation, 286 Pneumonia, acute lobar, communi- cability, period of, 63 disinfection, 64 entrance of infective agent, 63 exit of infective agent, 63 general measures, 64 immunization, artificial, 64 incubation period, 63 infective agent, 63 isolation, 64 methods of control, 63 quarantine, 64 route of transmission, 63 source of infection, 63 Pneumonic plague, 203-205 Pneumonokoniosis, 252 Poisons, industrial, 238 Poliomyelitis, communicability, period of, 63 disinfection, 63 entrance of infective agent, 63 exit of infective agent, 63 general measures, 63 immunization, 63 incubation period, 63 infective agent, 63 isolation, 63 methods of control, 63 quarantine, 63 routes of transmission, 63 source of infection, 63 Population, density of, 308 estimation of, 304 fluctuations of, 303-309 relation of, to vital statistics, 301 Pratique, 330 Precipitation, chemical, in sewage treatment, no Prematurity as a cause of infant mor- tality, 267 Prenatal clinics, 272-258 Preservatives, food, 225-226 Preventable diseases, losses from, 18 Preventive medicine, curative aspect, 20 definition of , 17 development of, 21 348 INDEX Preventive medicine, prophylactic aspect, 20 results from application of, 19 Primary case, definition of, 24 Privies, 298 leaching, 119 pail or can, 119 requirements for satisfactory, 117 vaulted, 119 Prostitution, relationship to alcohol- ism, 234 to venereal diseases, 41 Public health administration, 328 nursing, 335 physician's duties in, 333 scope of work, 21 service, U. S., 328 Puerperal septicemia, 256 state, diseases arising from, 255 deaths during, 255 Pure food legislation, 225 Purification of water, 131 results of, 143 selection of process, 144 self, of streams, 107 Pus pockets, dental, 277 Pyorrhoea, 277 Quarantinable diseases, list of (fed- eral), 330 Quarantine, definition of, 74 maritime, 329 Rabies communicability, period of, 212 disinfection, 214 entrance of, 212 exit of infective agent, 212 general measures, 214 immunization, 212 incubation period, 212 infective agent, 212 isolation, 212 methods of control, 212 quarantine, 214 route of transmission, 212 source of infection, 212 Rat as source of infection, 203 extermination of, 205 harbourage, 205-206 migrations of, 205 proofing, 205-295 Recessive characters, 261 Reciprocal notification, 85 Registration area for births and deaths, 316 Regulations, public health, 332 Relapsing fever, European, communi- cability, period of, 200 disinfection, 201 exit of infective agent, 199 immunization, 200 incubation period, 199 infective agent, 199 isolation, 200 methods of control, 200 quarantine, 200 route of transmission, 199 source of infection, 199 Relaxation, hygiene of, 292 Reportable diseases, selection of, 323 list of, 84 Resistance of animal infective agents, 3i of bacteria to desiccation, 31 to sunlight, 30 Rest, hygiene of, 292 Restaurants, 226 Reversionary inheritance, 264 Rockefeller foundation, 335 Rodents, 203-210 destruction by fumigation, 187 Round back, 275 Routes of infection, classification of, 32 of transference, classification of, 32 Rural population, 308 Sanitation, definition of, 17 Scarlet fever, communicability, period of, 55 disinfection, 55 entrance of, 55 INDEX 349 Scarlet fever, exit of, 55 general measures, 55 incubation period, 55 infective agent, 54 isolation, 55 method of control, 55 quarantine, 55 route of transmission, 55 source of infection, 55 Schick reaction, 60 School children, medical inspection of, 281 Schools, heating and ventilation of, 279 lighting of, 278 sanitation of, 278 Scoliosis, 276 Screening of dwellings, 299 sewage, 109 Scurvy, definition of, 230 distribution, 230 etiology, past ideas, 231 present ideas, 231 incidence, 231 prevention, 233 public protection, 234 Seating at school, 280 Secondary case, definition of, 25 Sedimentation of sewage, 109 of water, 133 Segregation of feeble minded, 266 Semmelweis, 256 Septic sore throat, communicability, period of, 56 disinfection, 56 entrance, of, 56 exit of, 55 general measures, 56 incubation period, 56 infective agent, 55 isolation, 56 methods of control, 56 route of transmission, 56 source of infection, 56 tanks, 109 Settling tanks, 109 Sewage, composition of, 105 Sewage, conditions making treatment necessary, 107 definition of, 105 disposal by dilution, 106 limiting factors, 107 results when satisfactory, 107 when unsatisfactory, 107 effluents and relation to anthrax, 216 finishing processes, 116 operation of plants, 109 preparatory processes, 109 purification processes, 114 results sought in treatment, 107 selection of treatment methods, 108 treatment, 107 Sewerage, definition of, 105 system, parts of, 105 Sewers, combined, 105 sanitary, 105 storm, 105 Sexes, ratio of, 308 Sheep grazing, 210 Shell fish, 176 Siderosis, 253 Silicosis, 253 Simplex combinations of determiners, 263 Slaughtering methods, effect on meat, i75 Sleeping quarters, 297 Sludge disposal, 112 Small-pox, communicability, period of, 48 disinfection, 49 entrance of infective agent, 48 exit of infective agent, 48 general measures, 49 immunization, 49 incubation period, 48 infective agent, 48 methods of control, 48 quarantine, 49 route of transmission, 48 source of infection, 48 Smith and Kilbourne, 22 35° INDEX Sources of infection, classification, 26 definition of, 25 influence of different types of sources, 36 lower animals as, 27 of anthrax, 215 of chicken pox, 50 of cholera, 69 of dengue, 196 of diphtheria, 59 of dysentery, amoebic, 70 bacillary, 71 of german measles, 54 of gonorrhea, 42 of influenza, 57 of leprosy, 65 of malaria, 188 of measles, 51 of meningitis, 61 of mumps, 52 of plague, 203 of pneumonia, 63 of poliomyelitis, 63 of rabies, 212 of relapsing fever, 199 of scarlet fever, 55 of small pox, 48 of spotted fever, Rocky Mountain, 210 of septic sore throat, 55 of syphilis, 41 of tetanus, 217 of tuberculosis, 64 of typhoid, 67 of typhus, 197 of uncinariasis, 72 of whooping cough, 56 of yellow fever, 195 Spotted fever, Rocky Mountain, com- municability, period of, 210 disinfection, 210 entrance of, 210 exit of infective agent, 210 general measures, 210 immunization, 210 incubation period, 210 infective agent, 210 Spotted fever, Rocky Mountain, isolation, 210 methods of control, 210 quarantine, 210 route of transmission, 210 source of infection, 210 Springs, protection of, 145-146 Stage, non-infective, 29 of invasion, 29 State public health administration, 330 Statistics, definition of, 301 vital, value of, 301-310 Stegomyia mosquito, 196 Sequelae of infectious diseases, 220 Sterilization, 99 of feeble minded, 265 Still births, 312 Storage of water, 132 Sulphur dioxid as insecticide, 101-186 as fumigant, 100 Susceptibles, 81 Syphilis, communicability, period of, 41 disinfection, 42 entrance of infective agent, 41 exit of infective agent, 41 general measures, 42 incubation period, 41 infective agent, 42 isolation, 42 methods of control, 41 route of transmission, 41 source of infection, 41 Temperature, effect of, on bodily comfort, 283 on insect vectors, 180-182 in relation to milk, 153 Tetanus, antitoxin, employment of, 21S communicability, period of, 217 disinfection, 218 entrance of, 217 exit of infective agent, 217 general measures, 218 immunization, 217 incubation period, 217 infective agent, 217 isolation, 217 INDEX 351 Tetanus, method of control, 217 quarantine, 218 route of transmission, 217 source of infection, 217 Throat, hygiene of, 277 Ticks, 210-211 Tieche test, 48 Tobaccosis, 253 Toilet facilities at schools, 280 Trachoma, 276 Training of water courses, 191 Transmission, routes of, classification of, 32 Transportation hazards, 241 of infective agents by insects, 180 factors influencing, 182 Trichiniasis, 176-203 Tuberculosis, as a cause of infant mortality, 270 bovine, 203 in milk, 169 communicability, period of, 64 disinfection, 65 entrance of, 64 exit of infective agent, 64 general measures, 65 incubation period, 64 infective agent, 64 incidence among those in dusty trades, 252 isolation, 65 methods of control, 65 route of transmission, 64 source of infection, 64 Typhoid fever, milk borne, 170 paratyphoid (enteric) group, com- municability, period of, 67 disinfection, 68 entrance of, 67 exit of, 67 general measures, 68-69 immunization, 68 incubation period, 67 infective agent, 67 isolation, 68 methods of control, 67 quarantine, 68 Typhoid fever, paratyphoid (enteric) group, route of transmis- sion, 67 source of infection, 67 Typhus fever, communicability, period of, 197 disinfection, 197 entrance of, 197 exii of infective agent, 197 general measures, 198 immunization, 197 incubation period, 197 infective agent, 197 isolation, 197 methods of control, 197 quarantine, 197 route of transmission, 197 source of infection, 197 Uncinariasis, communicability, period of, 72 disinfection, 73 entrance of, 72 exit of infective agent, 72 general measures, 73 immunization, 73 incubation period, 72 infective agent, 72 isolation, 73 methods of control, 73 quarantine, 73 route of transmission, 72 source of infection, 72 Urban population, 308 Utensils, eating, sterilization of, 227 milking, sterilization of, 152 Vaccination, gonorrhea, 43 influenza, 57 meningitis, 62 pneumonia, 64 small pox, 49 accelerated reaction, 50 course of eruption, 49 immediate reaction, 50 in infancy, 274 of exposed persons, 50 primary take, 49 352 INDEX Vaccination, small-pox, re-vaccination, course of, 50 technique of, 49 vaccine virus, 49 typhoid, 68 whooping cough, 57 Varioloid, 50 Vector, definition of, 25 Vegetables, fresh, as route of infection, 178 Venereal diseases (see syphilis and gonorrhea), medical prophylaxis of, 45 prevalence of, 43 standards for discharge of car- riers, 45 Ventilation, artificial, 286 domestic, 297 natural, 286 of schools, 279 poor, as occupational hazard, 237 Vision, defective, 276 Vital statistics, 301-310 Vitamines, 233 Water, conditions favoring contam- ination, 124 consumption of, 129 domestic supplies, 145 hygienic examination of, 126 importance of, 124 impurities, permissible limits for, 129 inorganic poisoning from, 125 relationship to health and disease, 124 source of supplies, 126 standards for, 121 transfer of infective agents by, 125 treatment of, coagulation, 133 disinfection of, 138 filtration of, 135 results of, 143 sedimentation, 133 Water, treatment of, storage of, 132 undesirable qualities, 131 water borne epidemics, 125 Welfare, child, centers, 273 Wells, pollution of, 145 protection of, 146 Whooping cough as cause of infant mortality, 269 communicability, period of, 56 disinfection, 57 entrance of, 56 exit of, 56 general measures, 57 immunization, 57 incubation period, 56 infective agent, 56 isolation, 57 methods of control, 57 quarantine, 57 route of transmission, 56 source of infection, 56 Wool, value as fabric for clothing, 294 Yellow fever, communicability, period of, 196 disinfection, 196 entrance of, 195 epidemic measures, 196 exit of infective agent, 195 general measures, 196 immunization, 196 incubation period, 195 infective agent, 195 isolation, 196 methods of control, 196 mosquito, 196 quarantine, 196 route of transmission, 195 source of infection, 195 Yersin's serum, 205 Zinc poisoning, 252 COLUMBIA UNIVERSITY LIBRARY This book is due on the date indicated below, or at the expiration of a definite period after the date of borrowing, as provided by the rules of the Library or by special ar- rangement with the Librarian in charge. 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