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Chapter I - Introduction

Contents

INTRODUCTION

CHAPTER I

General Considerations of Modes of Transmission

John E. Gordon, M. D.

The control of communicable disease remains the basic activity of military preventive medicine. Preventive medicine had its origin in the control of communicable disease and for many years was largely restricted to this field. As reasonable and useful additions were made to the program for prevention, the infections came to have relatively less emphasis, but the total effort expended in their control is still much the same. The typical organization of preventive services at the combat level in World War II consisted of a section each on epidemiology, venereal disease control, nutrition, and sanitation. Two of the four sections were wholly concerned with the control of communicable diseases, and the other two lead much to do with limiting the spread of infection. Comprehensive programs were planned by the Office of the Surgeon General and the theater commands, but the outstanding activity was still the control of communicable disease.

Programs of prevention have been broadened materially in the course of years to include battle casualties and nonbattle injuries as well as disease--the three recognized classes of death and disability in military practice. A refined knowledge of wound ballistics has led to major developments in body armor and other protective devices, along with changes in schemes for evacuation of the wounded. Nonbattle injury has superseded disease, including communicable disease, in importance as a cause of death in the Armed Forces in both peace and war, with the result that traumatic injury of accidental origin and poisoning due, to alcohol and to other toxic agents take a rightful place in preventive programs.

The concept of prevention of disease itself also has enlarged. Military medicine has had a leading part in the development of the science of mental health. Nutrition is recognized as a primary feature of preventive medicine. Occupational medicine originally attracted attention when it was restricted to industry, in which the Armed Forces have many interests related to the production of armaments; now it has become a matter of concern with respect to the health hazards which arise through the specific occupation of a soldier. Noninfective mass disease is not neglected, although conditions of this class have less significance in the Armed Forces than in a general population because the bulk of a military population is in the younger age groups.


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The continuing emphasis on communicable disease in the organization of military preventive services and in the underlying policies of military physicians holds in spite of a generally appreciated and well-documented decrease in deaths from communicable disease in the United States and in many other countries. Progress is most definite in nations of the Western World, but even there a measurable irregularity exists with respect to the various specific infectious processes. The development of antibiotics and the expansion of chemotherapy are a main influence in the lowering of the fatality rate; another influence is the lesser frequency of cases and hence the lowering of morbidity rates. The opinion is increasingly heard in general medical circles that the problems of communicable diseases are largely of a bygone day and that infections are now so adequately controlled that eradication in many instances is just around the corner. The military appraisal that communicable disease is far from being conquered presumably has justification.Military decisions of strategic nature rarely are made without a sound marshaling of facts.

COMMUNICABLE DISEASE IN MILITARY PRACTICE

A possible explanation of the emphasis on the communicable diseases in military preventive medicine is that military operations provide a situation different from that of civilian existence. Certain communicable diseases are in fact recognized as peculiarly military diseases, the diarrheas and the dysenteries and epidemic hepatitis being typical examples. Hemolytic streptococcal infections are frequently exaggerated in populations of young adults, such as an army. The common communicable diseases of childhood-mumps, measles, and the rest-always have been more of a problem under military conditions than in civilian life.

The potentiality of epidemics for a variety of diseases conceivably may be greater under military conditions, or the risk of epidemics may center peculiarly in those infections collectively grouped as the internationally quarantinable diseases (smallpox, plague) which flare up into world disaster because of the conditions of war.

The nature of an army population may be a decisive factor; military populations are young populations reasonably envisaged as having more than their share of infectious disease as compared with a general population.

The military physician, in developing his opinion of communicable disease, also may employ criteria other than those usual in civilian health practice, or he may have information not ordinarily available. For years, the costs of the communicable diseases have been measured in terms of the deaths they cause, largely by necessity, for the information on deaths is more complete and more reliable than that for incidence, length of disability, or residual defect. Morbidity reporting has never reached a satisfactory performance in any country, with the possible exception of Denmark . There is, furthermore, no need to deny the common clinical as well as lay, opinion that so long as a disease does not kill it is hardly worthy of note. Nevertheless, many diseases, such


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as the common cold and numerous helminthic infections, which have a far-reaching effect socially, economically, and medically, have little or no fatality rating. And, for those infectious diseases which are frequently fatal, morbidity rates supplement the knowledge derived from death rates. The practitioner of military preventive medicine has at his disposal information on morbidity of a quality not available in any other social organization; records of admission to hospital and quarters are a part of the military system. These data permit sound evaluation of noneffectiveness and of the reasons for discharge for medical disability. In military practice, both considerations are important, but no more so than in civilian practice.

The daily noneffective rate, that is, the number of men absent from duty, is an index of practical usefulness to physician and commander alike, for it measures, in part, the fighting efficiency of an army. It is a measure of disability; it is a measure of morbidity as contrasted to mortality; and, since an account is required of each man on the roster, it has unusual precision.

From a military standpoint, the loss of a man through discharge for permanent disability is equally as significant as a loss by death. In both instances, the Armed Forces are permanently depleted. The records of these losses are likewise complete. The costs of communicable disease are thus determined in terms of death, disability, and defect; that is, in terms of total cost. To evaluate the total cost of communicable disease is an endeavor incapable of practical fulfillment under conditions other than those of military practice. In the Army, judgment of a communicable disease and of communicable diseases in general thus rests on a broader base. A part of the optimism about control of the communicable diseases seemingly depends on opinion derived mainly from the number of resultant deaths, too little weight being placed on disability and permanent defect resulting from these diseases.

Newer and improved methods of mass control and clinical management have led to gains in the control of communicable diseases which are more or less evident everywhere. These gains are far from being evenly distributed, however. Within countries and between countries, economic and social conditions have limited the application of the newer and improved methods; a deficiency in medical facilities and professional training is sometimes a factor. The environment of Tropics and Arctics often introduces factors not present in the Temperate Zone where these newer methods have been standardized, with the result that procedure becomes more complicated or suffers in efficiency. At any rate, in large areas of the world containing the greater part of the human population, the, communicable diseases are still the main health problem. Modern war calls for troops to operate in these regions. The different environment and the greater seeding of infection may well lead to a poorer result in the control of communicable disease, even when Americans are managed under American methods.

For these and other reasons, the Army experience, in which more than 10 million Americans served under conditions foreign to their usual environment


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and mode of life, affords an opportunity to measure more accurately the extent of the progress that has been made in the control of communicable disease.

To look upon the communicable diseases as being now under control is at best provincial. Proof that they are under control scarcely exists so far as the United States is concerned, although the gains in the direction of control have been great. Communicable diseases are certainly not under control on a worldwide scale; and, in peace as well as in war, the world tends increasingly to become a single epidemiologic universe. Opinion concerning progress in the control of communicable diseases is too frequently based on deaths alone, an incomplete measure. Disability and residual defect are other primary considerations; good examples of diseases in which these two considerations are particularly important are acute upper respiratory infections and modern scarlet fever, respectively. That progress has been made in the control of communicable diseases is evident; conclusions on the extent of that progress are too often extrapolated beyond the existing evidence.

The record of the behavior of the communicable diseases in World War II is presented in this and other volumes of the preventive medicine series of the history with the primary purpose of demonstrating how much of a factor those diseases were in the conduct of military operations at that time. A secondary aim is to define those particular features which characterize the communicable diseases in military practice as contrasted with usual civilian conditions. The experience of this war was comprehensive, without parallel in the history of warfare. Similar methods and the same general policies were employed under a wide variety of environmental situations, from the Tropics to the Arctic . Conceivably, this experience may lead to an improved evaluation of the place of the communicable diseases in the public health practice of today. The first consideration is the system of classification of military casualties.

Classes of Military Casualties

Military casualties are divided into the following three categories: Battle casualties, nonbattle injuries, and those the result of disease. Disease is thus set apart from injury as a source of disability. Injury is further broken down into injuries of battle origin and those of noncombat origin. The classification of disabilities is generally clear cut but is sometimes arbitrarily made. For example, trenchfoot contracted in the line is classified as a nonbattle injury. Furthermore, similar disabilities may be classified as battle or noncombat in origin, depending on the circumstances under which the injury was sustained. A gunshot wound of the hand incurred accidentally in a training area or self-inflicted anywhere is a nonbattle injury and is distinct from the battle injury in which the same kind of wound results from contact with the enemy. The definition of terms that follows is taken from War Department Army Regulations No. 40-1080, dated 28 August 1945 .

Patients are classified according to the primary cause of initial admission, and their cases are reported in one of the following three categories: Disease, nonbattle injury, or battle casualty. In instances of patients suffering from


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both disease and injury at the time of initial admission, the most serious condition present is taken as the primary cause of initial admission and determines the classification. Patients admitted for a battle casualty and a disease or injury are classed as battle casualties. Thus, both primary and secondary diagnoses must be taken into account in determining the frequency of any particular condition, such as one of the communicable diseases.

All cases other than those due to injury or battle casualty are classed as disease. Included among the disease cases are those of patients suffering from reactions to medication other than acute poisoning, those of patients admitted for the sequela of an injury they had incurred before entering service, and those of patients readmitted for the results of a traumatism (battle or nonbattle) incurred during service.

Nonbattle injury includes traumatisms outer than those defined as battle casualties. Traumatism refers to morbid conditions due to external causes. The term is applied to acute poisoning, except food poisoning, and to the results of exposure to heat, cold, and light as well as to various types of wounds.

A battle casualty is a traumatism (wound or injury) which either is incurred as a direct result of enemy action during combat or otherwise or is sustained by an individual while he is immediately engaged in, going to or returning from, a combat mission. It does not include traumatisms occurring on purely training flights or missions. Psychiatric cases occurring in combat are not reported as battle casualties.

The measurement of losses from whatever cause is accomplished by computation of rates that relate to three principal demographic characteristics. The first of these, mortality rate, is an expression of the number of deaths from a particular cause that occur per unit of population and time, a frequent unit of population in military practice being 1,000 men and the interval of time 1 year. Mortality rates in this discussion are usually on the more practical basis of 100,000 average strength per year. The rates for shorter periods are based on the assumption that the observed frequency would have, continued over a year. The mortality rate represents a definite and certain military loss, irrespective of cause, of time, or of nature, and is one of the absolute indexes of the cost of war.

The morbidity rate, when expressed as an admission rate, refers to the number of persons affected by a given condition as determined by patients admitted to hospital or quarters and regularly is computed in terms of 1,000 per annum per average strength. Morbidity rates as so defined represent not all persons affected but only (1) those persons admitted to hospital or quarters (those seriously enough involved to be absent from duty), and (2), for most diseases, certain patients who are treated while they remain in a duty status and whose cases are carded for record only. Nevertheless, these indexes of illness as employed in military practice are more satisfactorily indicative of the existing situation than is usual in public health or preventive medicine, because reporting is particularly good. The significance of any particular morbidity rate as an influence on tactical and strategical operations depends, in the first


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instance, on the duration of the disability ordinarily associated with the condition; secondly, on the expected fatality; and, finally, on the prospect for complete recovery and return to duty.

The daily noneffective rate represents the number of men absent from duty by reason of disease or injury for each 1,000 troop strength per day. The complementary value shows the proportion available for duty at any prescribed time. Persons suffering permanent disability either partial or complete as a result of a disease or injury of sufficient seriousness to interfere with ordinary duties are discharged from military service. The designation of separation for disability is thus a measure of permanent defect, and numbers are listed by cause in relation to population concerned.

Most of the data on cases of disease in this and succeeding volumes are preliminary data based on sample tabulations of individual medical records. They include both primary and secondary diagnoses. As such, they are designated incidence. Admission rates refer only to primary diagnoses. Morbidity thus may be expressed in either term. Incidence is usual. The final tabulations will introduce some changes but presumably not enough to affect the interpretations made. In some instances, information is from weekly summary reports, field records which lack the reliability of analysis from individual medical records.

Data on deaths are on the same basis as data for cases, except that total deaths of the war (table 1) are from The Adjutant General's final report. Examination of individual case records will result in some rearrangement of the data of table 1 but not in number of deaths.

TABLE 1.-Admissions and deaths, by classification, U. S. Army, 1942-45

The communicable diseases are listed within a number of categories in the official tabulations. The most significant medically and from a military standpoint are the infectious and parasitic diseases, which represent those communi-


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cable processes of specifically determined etiology; they have an estimated incidence of 126.4 cases per annum per 1,000 average strength. The list is essentially that of the Office of Vital Statistics, United States Public; Health. Service, except that influenza, bacterial pneumonia, and rheumatic fever are included. The largest block of communicable disease is the common respiratory diseases with an annual rate for the total Army of 159.3 per 1,000. The diarrheas, excluding the dysenteries, are another appreciable source of morbidity; incidence 29.1 per 1,000 per year. Pneumonias other than specific bacterial, incidence 10.1, and fever of undertermined origin, incidence 5.7, are to be added. Miscellaneous items of lesser number, corresponding to those listed in Control of Communicable Disease in Man (American Public; Health Association, 1955) and not included among the categories given above contribute a further incidence of 12.7 per annum per 1,000; the main items are dermatophytosis, impetigo contagiosum, and trachoma. The greater proportion of the conditions listed are infectious and reasonably to be added to the specific infectious and parasitic diseases in accumulating a total of communicable disease. Rates of incidence as here cited are in part estimates, particularly for cases reported as secondary diagnoses during 1942 and 1943. The incidence for all communicable disease on this basis is 343.3 per annum per 1,000.

The information on admissions (primary diagnoses) is almost complete. The rate for disease for the total Army during 1942-45 was 587.5 per annum per 1,000 average strength. Similar data for the communicable diseases as just presented give an admission rate of 310.4. Thus, in the total Army during the war, more than one-half of all reported disease was of a communicable nature.

The aim now is to determine the place of communicable disease among military casualties, and the influence of these diseases on military operations, in this war and in relation to other wars and other years. The practical approach initially is through disease of all forms principally, because the communicable diseases were more than one-half of total disease in World War II, because the exact numbers of infections remain indeterminate by reason of indefinite clinical identification within several large groups, and because in records of earlier years the separation of communicable from other disease processes was still looser.

DISEASE AS A FACTOR IN MILITARY OPERATIONS

The ratio of deaths from disease to deaths from battle casualties for the wars of the 18th and 19th centuries was sometimes as great as 12 to1. A generally accepted ratio was 4 to 1; as for example, in the Russo-Turkish War of 1877-78 where deaths from disease numbered approximately 80,000 and those from battle casualties 20,000. The ratio during the campaign in the Crimea was even greater, with some 70,000 deaths from disease and 7,500 from battle casualties among the French forces. Approximately three-fifths of the disease


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and battle deaths that occurred in the Union Army during the American Civil War were deaths from disease, which marked an improvement over the Mexican War when deaths from disease outnumbered those from battle casualties in the proportion of 6 to 1. The ratio during the Spanish-American War was lower, with an excess of deaths from disease over losses in battle in the proportion of about 5 to 1.

Fewer deaths from disease than from battle casualties were noted for the first time in the War of 1864 which Denmark waged against Austria and Prussia (table 2). Both opponents established a ratio of 1 death from disease to 2 for casualties of battle. Although the number of men engaged in that war was small, communications between the armies and home countries were good and environmental conditions were favorable. The War of 1864 was nevertheless a remarkable event-a turning point in the history of wars. In the FrancoPrussian War of 1870-71, the first major war to see the new ratio maintained, the German Army had a proportion of 0.86 deaths from disease for each battle casualty. The health record of the German Army has been consistently good, for of five wars, dating from the Danish action of 1864 and including World War I, deaths from disease have been less than those from battle casualties with the single exception of the War of 1866 and that was close to parity. The Russo-Japanese War of 1904, the next great conflict after the Franco-Prussian War, gave the Japanese forces an opportunity to set a new ratio of 0.37 deaths from disease per battle casualty.

World War I was the first United States experience in which deaths from disease were fewer than deaths from battle casualties, and then this was true only in relation to troops in the active European campaign of 1918 (table 2). For the United States Army as a whole and for all men under arms, the rate was still slightly greater for disease. World War II brought a complete departure from previous experience and a health record never approached previously in any war. The ratio of deaths from disease to those from batty casualties was 0.07: 1.

The gains which have been made in recent times are primarily due to improved control of acute infectious disease. Not only are deaths from this cause far less frequent in proportion to those at risk, but the case incidence of communicable disease is decidedly less. This has brought significant changes in the qualitative character of the losses that still result from disease as distinguished from injury and battle casualties. Noncommunicable disease has become increasingly important, especially psychiatric disorders, aside from considerations of loss by death.

Of all deaths for all United States troops under arms in World War II, 75.2 percent were due to battle casualties, 19.7 percent to nonbattle injury, and 5.1 percent to disease (table 1). The established excess of deaths from disease over deaths from battle injury was strongly reversed in World War II. Even nonbattle injuries became a more important source of fatal casualties. Deaths, however, are not the sole measure of costs of disease and injury, nor are they


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TABLE 2.-Deaths from disease and battle deaths in principal wars, foreign armies and U. S. Army, 1846-1945


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always the most indicative. The intent now is to examine disease in World War II in relation to the two classes of injuries, battle and nonbattle, and then to relate the specific infectious and parasitic diseases to disease as a whole.

Mortality From Disease

Disease in World War II ranked third among major classes of deaths (table 1). The contrast with other wars is extreme, where deaths from diseases outnumbered the total of all others and sometimes in a proportion inversely as great as that presented here. On the basis of deaths, disease clearly has decreased significantly as a factor in military operations.

Disease Morbidity

As a cause of disability in World War II, disease ranked first among the three major categories of military casualties (table
1); in fact, the number of admissions for disease was more than five times as great as the number of admissions for battle casualties and nonbattle injuries. Somewhat more than 85 percent of all admissions to hospital and quarters were because of conditions

CHART 1.-Admissions to hospitals and quarters for diseases, nonbattle injuries, and battle casualties, ETOUSA, 1942-45 1


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classed as disease. The experience of ETOUSA (European Theater of Operations, United States Army) is cited as an example since that theater was the largest and since environmental conditions there were those of a temperate region.

For each of the 4 years that the European theater was in existence, disease was the most frequent cause of admission to hospital or quarters (chart 1). The highest admission rate was in 1943, the widespread epidemic of influenza in the autumn of that year being a contributing factor. The rates from year to year showed little variation, irrespective of whether the battle was fast or slow. There was no direct correlation between the activity of military operations and the frequency of disease. The numbers of persons affected were regularly great, since each year about one out of every-two soldiers tended to suffer some disability from disease of sufficient degree to interfere with military duties. The regularly occurring annual peak of incidence in late autumn or early winter (chart 2) shows common respiratory infection to be the dominant factor in frequency of disability due to disease.

CHART 2.-Admissions to hospitals and quarters for all diseases, ETOUSA, by month, 1942-1945 1


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No particular significance attaches to the experience of the first 2 years in the European theater. The morbidity rates for disease were in all respects satisfactory and the health record good. The striking feature is in respect to the last 2 years. During the height of the campaign in continental Europe which started in the middle of 1944 and ended in late spring of 1945, the morbidity rates for disease as judged by admission to hospital and quarters were at a lower level (chart 2) than at any other time during the war. Proverbially and throughout the history of wars, this is the time when losses have been great. Granted that many soldiers will not report sick during the height of military operations, and particularly in time of advance, nevertheless, the fact that so few were disabled by disease is perhaps the clearest evidence of the progress made in environmental sanitation and in the practice of preventive measures.

Noneffective Rates for Disease

The proportion of a command absent from duty on a particular day is a reflection of current morbidity and of the deaths that occur. The extent of noneffectiveness is also an index of the kinds of disability, for those of disease in the age groups that characterize an army are commonly short while those of injury whether of battle or nonbattle origin tend to be longer. Disease is the main component of noneffective rates. For the Army as a whole and over the war period, the preliminary estimates per day per 1,000 average strength are 6.38 for nonbattle injury, 7.73 for battle casualty, and 30.22 for disease.

The significance of the noneffective rate and the drain on operating efficiency of an army is expressed in simpler terms by consideration of the number of man-days lost. Estimates in round numbers show a total of 72 million days lost because of battle casualties for all the Army troops, including the Air Force, during World War II. This exceeds the corresponding figure of 59,863,000 for nonbattle injuries, but scarcely approaches the loss of 285,918,000 days attributed to disease (table 3). A comparable estimate for days lost because of infectious and parasitic disease is 55,688,000 days of the total 285,918,000. The experience of ETOUSA again is drawn upon to indicate


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CHART 3.-Average daily noneffective rates, ETOUSA, by months, February 1942 to June 1945, inclusive

variations in noneffectiveness over time (chart 3). The data are from field records but are sufficiently- reliable to establish relationships and trends.

Discounting the early part of 1942 when the small troop strength of the European theater accounted for irregularities in the demonstrated pattern, each year of the 4-year period of World War 11 saw the high point of noneffectiveness centered about the early months of the calendar year and minimal values during the summer. The seasonal incidence of upper respiratory infections was the main influence on this fluctuation. Variations from year to year were not great until the latter part of 1944 when the values for all months increased precipitately over the established norm. This was coincident with the beginning of active operations in Continental Europe.

The division of this particular combat experience into the three components which make up the total noneffective rate (chart 4) gives ready demonstration of the factors involved. The noneffectiveness related to disease continued according to established pattern, with rates in 1945 almost identical with those that characterized 1944, the year just preceding the campaign. A significant part of the excess noneffectiveness came about through a greater frequency of nonbattle injuries, principally cold injury. The most important variable was that of battle casualties, with the data of chart 4 demonstrating clearly the high noneffectiveness of the campaign period as due to that cause.

The generalizations to be drawn from this experience are that year in and year out the principal cause of noneffectiveness of troops is disease. The losses from nonbattle injuries are ordinarily much less, about one-fifth of those from


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CHART 4.-Average daily noneffective rates for disease, nonbattle injury, and battle casualty, ETOUSA, January 1944 to June 1945 inclusive

disease. The noneffectiveness that comes from battle casualties is subject to great variation wholly related to the nature of operations. The impression is not to be left that the cost of battle casualties is unpredictable, for the expected losses in a major operation can be estimated with an exactness rivaling those of disease and injury.

All three classes of casualties give rise to irregular fluctuations in morbidity and in noneffectiveness which can be related with much certainty to environmental, seasonal, or other ecologic factors. The peaks of excess incidence that mark the behavior of battle casualties and nonbattle injuries may be as outstanding as any introduced into the general curve through action of an epidemic of disease.


Discharge for Permanent Disability

The final consideration of noneffectiveness is that of separation from the military service by reason of physical or other disability, variously due to residual effect of battle casualty, nonbattle injury, or disease. Such losses in World War II greatly exceeded the losses from death; death accounted for 312,293 absolute losses, separation because of significantly impaired usefulness the much greater number of 956,232. The distribution according to class of


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casualty is shown in table 4, the data being for enlisted men only. Battle casualties were a greater factor than nonbattle injuries, but disease was almost eight times the sum of the other two.

TABLE 4.-Separation from service, by cause, enlisted men only, U.S. Army, 1942-45

The endeavor now is to identify the contribution of the communicable diseases to these several rates and indexes. The main reliance is on those conditions collectively grouped as the infectious and parasitic diseases, a category used in common in both military and civilian vital statistics although with minor variation in the diseases included. The group is not synonymous with the communicable diseases. Many diarrheas are surely dysentery, to such an extent that the two conditions are considered jointly in a subsequent chapter. They cannot be adequately separated. An interpretation based solely on confirmed bacillary dysentery, even with clinically recognized dysentery added, is not representative. The common respiratory diseases presumably include a goodly proportion of the influenzas; this group is excluded and so is a part of the pneumonias. Large numbers of fever of undetermined origin in malarial zones are actually malaria. The infectious and parasitic diseases (as listed in table 10, p. 26) are however the main problem and in large measure determine the military significance of the communicable diseases.

THE SPECIFIC INFECTIOUS AND PARASITIC DISEASES

The long-term behavior of the infectious and parasitic diseases in respect to the general population of the United States is to be ascertained through comparison of deaths from these diseases with deaths from all causes; it is a


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useful control in judgment of the military experience. Deaths are the necessary criteria because reporting of cases in the general population is incomplete for all of the communicable diseases, and a number are not reported at all. Selected years indicate a consistent and impressive downward trend (table 5). Infectious and parasitic diseases, as listed by the Bureau of the Census in Vital Statistics of the United States , do not include pneumonia and influenza, whereas United States Army tabulations for World War II include bacterial pneumonia and influenza.

TABLE 5.-Deaths, all causes, and deaths from infectious and parasitic diseases, total United States, for 1900, 1925, and 1950

Death rates for infectious and parasitic diseases show a material variation (table 6). Rates increase progressively with age, tuberculosis being a major influence. The proportion of deaths from infectious and parasitic diseases to deaths from all causes is materially greater at the younger ages. One reason for the emphasis on communicable diseases in military practice is thus evident. Military populations have a strong bias in ages in which the infectious and parasitic diseases account for the largest proportion of deaths and also a bias in males, among whom death rates exceed those for females.

The greater problem presented by the infectious and parasitic diseases in the general as contrasted with the military population of the United States is illustrated in chart 5 where the rates for the two populations are compared by 5-year periods from 1900 to 1950. The list of infectious and parasitic diseases is again that of the Office of Vital Statistics, pneumonia and influenza being deleted from the Army data. The frequency is regularly less in the military population (chart 5) which is primarily of young adults. The more valid comparison is with males aged from 20 to 29 years of the general population; the advantage still holds.


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TABLE 6.-Average annual deaths, all causes, and deaths from, infectious and parasitic diseases, total United States, by age groups, 1948-52

CHART 5.-Deaths front infectious and parasitic diseases (with pneumonia and influenza excluded from Army data), 1900-50


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Army Experience Over the Years

The extent of the problem provided by the infectious and parasitic diseases is measurable for the Army in terms of both morbidity and mortality, something which is not possible for the civilian population. Admissions to hospital and quarters represent, within limits of human fallibility, all illnesses due to specific infections where specific infection was the primary diagnosis. Because of coding practices which prevailed from 1924 through 1943, data for that period as well as for the war years 1942-45 may be considered for all practical purposes as representing incidence; namely, both primary and secondary diagnoses. Data from 1946 are admissions, primary diagnosis, only. The series of data in chart 6 includes the last five wars of this country. They mark the coming and going of epidemics and the intervening endemic periods but, withal, the continuing downward trend in morbidity and mortality. The high point in cases and deaths is that of the Spanish-American War, 1898, with an admission rate somewhat less than 1,000 per annum per 1,000 average strength and a death rate of 21 per 1,000. The influenza epidemic of

CHART 6.-Admission1 and death rates for infectious and parasitic diseases, in the U.S. Army, 1895-1954


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1918 and the lesser event of 1920 are readily identified. Mobilization years of 1917 and 1940 produced higher rates as recruits were brought together in large numbers. The fluctuations from year to year were sometimes great, but the outstanding observation is that deaths from this group of diseases showed almost no departure during World War II from the established trend; this was despite potential hazards never before faced by our military forces.

Previous Wars

The changing behavior of the communicable diseases is strikingly brought out by comparison of morbidity and mortality rates for infectious and parasitic diseases in the several wars of United States history for which records are reasonably reliable (table 7). Deaths per 1,000 average strength have dropped

TABLE 7.-Admissions and deaths from infectious and parasitic diseases, U.S. Army, in 4 major wars, 1861-1945

from a rate of 34.77 for white Union troops of the Civil War (1861-65) to a rate of 0.15 in World War II (1942-45). Morbidity has by no means decreased proportionately, but the admission rate of 112.46 in World War II is wholly satisfactory in relation to the admission rate of 1,030.34 of the Civil War. Each successive war showed definite and progressive improvement over its predecessor; the proportionate gain in World War II over World War I far outdistanced all others.

World War II

About 20 percent of all reported disease in the Army for the war years of 1942-45 was in that group classed as infectious and parasitic diseases, excluding rheumatic fever, the number of cases being nearly 3,200,000 to give an incidence


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rate of 124 per annum per 1,000 average strength (table 8). Numbers of cases were about equal for troops stationed in the United States and overseas, but the rates were materially greater for overseas troops. Troops stationed in continental United States had a rate of 107; the rate for those serving abroad was 148. The proportion of infectious and parasitic diseases to all disease was of similar order, for 18 percent of reported cases at home were of this nature; the frequency for troops serving in theaters of operations was 26 percent.

TABLE 8.-Admissions for all disease and incidence of infectious and parasitic diseases in the U.S. Army, by theater or area of admission, 1942-45 1

Parallel relationships held for deaths from specific communicable disease (table 9). The proportion of deaths from infections to deaths from disease of all forms in the Army as a whole was measurably greater, however, than the similar ratio for cases: 25 percent for deaths and 20 percent for cases. For troops stationed in the United States , some 20 percent of all deaths from disease were due to infections; the proportion overseas was just about three-fifths greater, or 32 percent. The spread between absolute death rates from infectious disease at home and abroad was also strikingly different-11 per annum


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per 100,000 average strength in the United States and 20 overseas. Stated in other fashion, the risk of contracting an infectious disease during service overseas was greater than at home and the risk of death from such disease was still greater.

A possible explanation of this situation is that the communicable diseases of overseas areas included infectious processes characterized by higher fatality than existed in the United States . There is the second possibility that the kinds of infectious disease were much the same but with enhanced fatality related to environmental differences. A third consideration is that the decisive factor may be the stress and strain of combat, a mode of life in the field contrasted with that in training and in barracks and with attendant difficulties in providing an equal quality of medical care. The same considerations enter into explanation of the attack rates abroad, which are appreciably greater than under home conditions but less so than the observed differences in death rates.

TABLE 9.-Deaths from all disease and from infectious and parasitic diseases in the U. S. Army, by theater or area of admission, 1942-45

The contribution of the infectious and parasitic diseases to the total amount of disease resulting in separation from the service because of disability was insignificant. Among enlisted men only 2.6 percent of total separations


24

were for these diseases, as opposed to 88.5 percent for disease of all forms. The total number of separations because of the aftereffects of infectious and parasitic disease is, however, impressive; in all, 25,115 among enlisted personnel.

The distributions of infectious disease by theaters of operations, by the several years of military operations, and by the kinds of communicable disease that characterized each may now be examined to advantage. To do this, it is necessary to know the size and nature of the problem in its entirety; that is, to know the kinds of infectious and parasitic disease, with the number of admissions or cases and of deaths for each, experienced by the United States Army in World War II (table 10).

Distribution by Areas and Theaters of Operations

Incidence of infectious and parasitic disease varied greatly from one theater to another, from a low rate of 53 per annum per 1,000 average strength in the North American area (table 8) to a high of 247 in the China-Burma-India theater. Other theaters and areas with high incidence were the Middle East (rate 228), Mediterranean (rate 222), and the Southwest Pacific (rate 194). A scant familiarity with these regions is enough to bring out the low levels of environmental sanitation, the greater frequency of infection among peoples resident there, and the common presence of some kinds of communicable disease scarcely known in temperate regions of the Western World.

High rates for communicable disease among foreign troops operating in such regions would be anticipated, because of the strange environment and because of a susceptibility presumably greater than that of persons indigenous to the region. It is a matter of satisfaction, however, that when environmental conditions were similar and risks comparable, the morbidity rates for communicable disease in soldiers overseas compared favorably with those of troops stationed in continental United States . The North American area and the European theater actually had better rates, although allowance must be made for the problems associated with recruits in the Zone of Interior and the selection and greater resistance of seasoned troops sent overseas.

Morbidity rates for infectious and parasitic diseases in the North American area (53 per annum per 1,000 average strength) were not only the best of any area or theater of operations but they were about one-half those for troops of continental United States . A portion of the territory of this theater was American, with the advantages of close cooperation with civilian health authorities and an organization for health which followed the United States pattern. Troops were isolated from contact with civilian populations more than in many situations, either at home or abroad. Troop strength was small and relatively stable, lacking the continual buildup which characterized so many operational areas. These factors presumably restricted the continuous

seeding of a command with newly introduced infection. On the other hand, troops


25

of this region of ten were subjected to rigorous cold and a primitive environment which found expression in unusually high rates for nonbattle injury, a type of disability which then and now is a feature of cold climates. This environment might well have been expected to favor occurrence of communicable diseases. The observed rates are wholly commendable.

The European theater, the largest in respect to troop strength and the site of some of the most active combat of the war, had incidence rates for infectious and parasitic diseases which averaged 106 per annum per 1,000 average strength for the 4 war years, a rate about equal to that for continental United States, which was 107. Climate and environmental conditions were much the same as those to which troops were accustomed in the United States . For troops stationed in Britain , a high grade of cooperation existed with civilian health authorities and with an old and well-established health organization.

Two conclusions may be drawn. First, armed warfare does not of itself bring increased hazard of the communicable diseases to troops in areas of active combat. The European theater had rates about equal to those of continental United States which was a training area with no open warfare. Within the European theater itself, communicable disease was of more concern in service troops of the Communications Zone than in combat units in forward areas. Second, excess incidence of infectious disease seems in this experience clearly related to environments conducive to greater risk and to military operations in areas of known high prevalence of these diseases. Another reason for emphasis on communicable disease in military practice thus becomes evident the need in global warfare to operate in regions where the communicable diseases are the main factor in morbidity and where rates for infectious and parasitic diseases in American troops may be expected to be greater than those prevailing in the home country.

Deaths by areas and theaters of operations

With minor exceptions, death rates from infectious and parasitic diseases arrange themselves in much the same order for the several theaters of operations as do rates for cases (table 9). When incidence is high, mortality is high. The China-Burma-India theater with highest incidence had a mortality rate of 53 per annum per 100,000 average strength and the North American area with the lowest incidence had the lowest death rate, 10 per 100,000. Material differences in rates between theaters are evident.

Death rates from communicable disease in the theaters have a greater spread over death rates of Zone of Interior troops than do rates of incidence in these two elements of command. For example, morbidity rates for these diseases as a whole in the China-Burma-India theater were a trifle more than twice those for continental United States ; mortality rates were five times as great. The North American area had less than half the continental United States morbidity rate, but death rates were about equal in the two areas.


26

TABLE 10.-Cases and deaths due to certain infectious and parasitic diseases 1 in the U.S. Army, 2 by diagnosis and area of admission, 1942-45


27

TABLE 10.-Continued


28

TABLE 10.-Cases and death due to certain infectious and parasitic diseases1 in the U.S. Army, 2 by diagnosis and area of admission, 1942-45-Continued


29

TABLE 10.-Continued


30

The European theater had approximately the same incidence rate as continental United States but had a mortality rate of 12 per annum per 100,000 average strength compared with 11 for the continental United States . Broadly viewed, the morbidity rate for infectious and parasitic disease among all troops overseas compared with those at home was greater by about 39 percent. Death rates for these diseases overseas were essentially 100 percent more than in the Zone of Interior.

Possible explanations are that the kinds of infectious disease active in the two situations are different, that diseases present in common occur with greater severity, or that differences in quality and facilities for medical care are a determining factor. The validity of the first two assumptions may be determined from examination of the detailed frequencies of cases and deaths by individual diseases as presented in table 10. The third possibility is difficult to evaluate, involving as it does the balance between preventive and curative services and the lack of factual data capable of quantitative analysis. One conclusion is definite: death rates for infectious and parasitic disease in overseas troops are in this experience proportionately greater in relation to incidence than for Zone of Interior troops, a circumstance which holds whether absolute incidence in the particular theater is high or low.

This analysis of cases and deaths from infectious and parasitic disease in the war years of 1942-45 is now extended from differences according to place (overseas theaters of operations in comparison with the Zone of Interior) to a consideration of time relationships. The suggestion has been raised that the significance accorded to communicable disease in military practice may rest in more frequent occurrence of epidemics of the usual fluctuating endemic diseases or in outbreaks or threatened outbreaks of the great pandemic diseases which include the designated internationally quarantinable diseases and influenza. If that be so, then irregularities in cases and deaths should be evident in random fashion from one year to another, affecting parts of the total command, and identifying local epidemics; or a uniform irregularity marking a single year, affecting all theaters, and establishing the presence of a pandemic of the nature of the influenza outbreak of the First World War.

Communicable diseases by years, 1942-45

An outstanding feature of the incidence of infectious and parasitic disease among troops of continental United States (1942-45) was the regularity of occurrence from one year to another (table 11). The rates were in close agreement; the best year was 1944 with a rate of 100 per 1,000 average strength.

No serious deviation in the proportion of cases of infectious and parasitic disease to all disease occurred during the 4-year period, either in the Zone of Interior or overseas; the ratio in both instances was greatest in 1945. Since the two major fractions of the command behaved in similar fashion, it follows that the same pattern held for the total Army.

Rates of incidence for overseas troops were on an average some 39 percent higher than for troops in the Zone of Interior, but the trend in behavior over


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TABLE 11.-Incidence and deaths from infectious and parasitic diseases in the U. S. Army, by area of admission and year, 1942-45 1

the 4 years was much the same for both. The second year of the war, 1943, had increased rates over the first year, appreciably so for troops overseas; the most favorable rates were in 1944, and incidence returned to the higher levels of 1942 and 1943 in the last year of combat.

Death rates for the infectious and parasitic diseases during the 4 years and for the Army as a whole followed the same pattern as the rates for cases except that the rise in 1945 was lacking for ZI troops, the shifting of units and rapid demobilization having an effect on troop strength and therefore on rates.

The ratio of deaths from infectious disease to deaths from all disease for the Army as a whole was fairly fixed throughout the war; the moderate increase in 1945 was related to troops overseas.


32

These four sets of data, the ratio of cases and of deaths from infectious disease to all disease and the annual rates for cases and deaths due to infectious processes, suggest the general behavior of communicable disease during the war to have been characterized in the first 2 years by a somewhat enhanced endemic level of infection, punctuated by local epidemics. This circumstance is usual for recruits brought together in large numbers as in the continental United States . Rubella and meningococcal meningitis in 1943 were good examples of the kinds of epidemics that occurred.

Troops arriving overseas had, in some instances, the advantage of fairly prolonged seasoning, but often they did not. Irrespective of seasoning, in foreign theaters they commonly faced infections with which they had had no previous experience, such as filariasis in the South Pacific and scrub typhus in the Southwest Pacific Area. Amebiasis, ordinarily an endemic disease, reached epidemic proportions in the China-Burma-India theater and several others. Both continental and overseas troops thus encountered an unfamiliar mode of life, a strange environment, and, for overseas troops, a life in places where risk of contact with infection was notably greater than any to which they had been accustomed.

The rates for infectious and parasitic disease that prevailed in the third year of the war seemingly represent expectancy in terms of a trained functioning army. Case rates and death rates were improved both in the Zone of Interior and overseas.

Both incidence and mortality were greater in 1945 for the Army as a whole. The incidence rate for home troops was in general comparable to that of the recruit years, but the mortality rate was as low as in 1944. For overseas troops, both rates were comparable to those of early adjustment to the new conditions of a theater. The excess was largely related to the period when the war ended and thereafter.Until the war ended, the record for 1945 was much the same as for 1944. In the postwar period, military discipline relaxed, and control measures were more difficult to apply; for some diseases, especially the venereal diseases, rates increased precipitately. Recovered prisoners of war also made their contribution to greater incidence and mortality, particularly in respect to tuberculosis.

Two medical events were of general occurrence, affecting troops in appreciable numbers both in the Zone of Interior and overseas. The first, in 1942, was the manmade epidemic of serum hepatitis; the second, in 1943, was an outbreak of influenza A. The data discount the outstanding prevalence of any one of the great epidemic diseases, the famous six quarantinable diseases.

Interest now turns to the kinds of communicable disease involved in the troubles of recruits in the Zone of Interior and of newcomers to an overseas theater of operations, to identify such local epidemics as occurred under both sets of circumstances, to compare the endemic disease that characterized the various theaters of operations, and especially to view the behavior of what history has long established as the infectious diseases peculiar to military operations.


33

Continental United States

The problems of specific communicable disease in continental United States centered mainly in the first 2 years of the war in which rapid buildup of the Army was taking place. They were the problems of recruits.

Tuberculosis of all forms was consistently at a low level, 1.48 cases per annum per 1,000 average strength. for the 4 years, largely because of the effective screening at the time of induction. The first and final years had a higher incidence than the intervening years, 1.86 and 2.16 per 1,000, respectively. The death rates for tuberculosis decreased from 3.46 per 100,000 average strength in 1942 to 2.15 in 1945, the average for the 4 years being 2.64.

As in theaters of operations, the venereal diseases in the Zone of Interior contributed strongly to the incidence rate of the infectious and parasitic diseases. Indeed, for the war years as a whole, gonorrhea headed the list for reported cases of infectious and parasitic disease both in the continental United States and overseas. The 1942 rate for gonococcal infection in troops of continental United States was 31.44. In 1945, this rate rose to 43.21, a circumstance which held for a number of the communicable diseases as discipline relaxed with the end of the war and an association with civilian populations was greater and easier. Syphilis, excluding neurosyphilis, started with a satisfactory rate of 6.88 in 1942, reached a high point of 19.60 in 1944, and declined thereafter. The incidence of chancroid in Zone of Interior troops was one-fifth that of troops stationed overseas. Rates for gonorrhea also favored troops at home, 31.52 compared with 38.81 per 1,000 for overseas troops as a whole and for the war period. Overseas troops had much the better rates during the first 3 years, but, with cessation of active combat, that advantage was lost in 1945 when gonococcal infection increased to such extent that the year ended with an annual overseas incidence of 55.72. For the war period as a whole, syphilis was far more frequent among Zone of Interior troops than those overseas, the respective rates, excluding neurosyphilis, being 15.12 and 8.89 per annum per 1,000 average strength.

Influenza among troops in continental United States was more or less limited to the first 2 years of the war, as it was in most foreign areas where American troops were stationed. Incidence was somewhat higher, 16.20, in 1942, but the bulk of cases occurred in 1943 during an epidemic of type A. Death rates were low, 0.30 and 0.15 per 100,000, for the 2 years. Cases and deaths from bacterial pneumonia were in the same pattern, with the highest admission rate (3.52 per annum per 1,000 average strength) in 1942.

Meningococcal meningitis was second among causes of death from infectious and parasitic disease with rates of 2.41 per 100,000 strength per year in 1942 and 4.48 in 1943, the 4-year average being 2.58. Meningitis thus holds its place among communicable diseases of military significance, but the epidemic of 1943 (incidence rate 1.23 per 1,000) was a minor event compared with the outbreaks of World War I.


34

The common communicable diseases of childhood consistently give concern in recruit populations. All were relatively frequent in the first 2 years, with the exception of whooping cough which seems never to give much trouble in armies and chickenpox which regularly is less frequent than mumps, measles, and rubella. In order of frequency, mumps commonly ranks first; measles, somewhat erratic, usually second; and rubella, third. In the World War II experience of troops in the United States, mumps behaved satisfactorily, incidence 5.59 per annum per 1,000 average strength; measles was of lesser consequence, 3.69 per 1,000; while rubella in this instance produced the epidemic with 125,530 cases and an incidence of 8.51 per 1,000. Most cases of rubella (88,775) occurred in 1943 to give an attack rate of 17.13 per 1,000 average strength. Chickenpox as usual was inconsequential, incidence 0.58 cases per 1,000 strength. The frequency of both chickenpox and mumps remained much the same over the 4 years.

Epidemic hepatitis and coccidioidomycosis provided problems of special note among infectious and parasitic diseases of continental United States troops. Hepatitis was largely limited to 1942, with 33,569 admissions, a rate of 12.63 per 1,000; this was primarily serum hepatitis, easily the largest epidemic of this particular form ever recorded. A full account is given in another volume. 1

Thereafter, infectious hepatitis, a disease justifiably included among infections of military importance, was the prevailing form. The rates for infectious hepatitis were low in 1943 and 1944, but the last year of the war gave an annual admission rate of 2.08 per 1,000 average strength. In the continental United States , the rate never reached the proportions that it did in a number of overseas theaters, especially in the last 2 years of hostilities. Serum hepatitis occurred among overseas troops in 1942, but thereafter it was the directly communicable infectious hepatitis that was responsible for the continued high admission rates among troops overseas-14.79 in 1943, 6.44 in 1944, and 15.16 in 1945.

Coccidioidomycosis, by contrast, was mainly a disease of troops in the United States . Of 3,809 cases for the Army as a whole, 3,626 were in continental United States . For the 4-year period (1942-45), the greatest number of cases, approximately 1,310, occurred during 1943. Deaths totaled 32 in the United States and 7 overseas. The death rate was not great (0.22 per annum per 100,000 average strength in the continental United States ), but the behavior of the disease and the problems presented were an outstanding event of World War II medicomilitary history (p. 286).

Among continental United States troops, the chief causes of death due to infectious and parasitic diseases were tuberculosis, 2.64 deaths per annum per 100,000 average strength; meningococcal meningitis, 2.58; bacterial pneumonia, 1.69; poliomyelitis, 0.58; and infectious hepatitis, all forms, 0.55. Deaths from infectious hepatitis may have been underreported.

1 Medical Department , United States Army. Preventive Medicine in world war II. Volume V.Communicable Diseases Transmitted Through Contact or Unknown Portals of Entry. [In preparation.]


35

European Theater of Operations

In the European theater, the incidence of infectious and parasitic diseases, next to the lowest among theaters of operation and about the same as that of continental United States troops, suggests little of particular note in a command that at one time involved more than 3,000,000 men and stands as the largest foreign effort of the United States Army in this or any other war.

The influenza epidemic of the early years of World War II was more or less worldwide. Incidence was greater among troops of the European theater, 20 and 18 per 1,000 for the years 1942 and 1943, than for troops at home and indeed was exceeded only by the experience of the Mediterranean theater, 39 and 15 per 1,000 during the same 2 years. The Eastern or Pacific theaters were less affected than those of the West or Atlantic area. As a consequence, over-all rates for troops at home and those abroad favored troops overseas; Zone of Interior troops lead incidence rates of 16 in 1942 and 13 in 1943; for all troops overseas, incidence was 12 and 12 per 1,000 in the corresponding years.

Rates for bacterial pneumonia were in those years appreciably higher in continental United States than in overseas areas, even in the European and Mediterranean theaters where influenza was more common. This contrast invites consideration as to the contribution of exposure, which is presumably greater in field operations than in training areas.

The venereal diseases lead an erratic history in the European theater. Incidence during the years of active combat was lower than among troops at home, but when the war ended this advantage was quickly lost. The incidence rate for gonorrhea in 1944 was 24.79 per 1,000; in 1945 it increased to 71.71. Chancroid rose from a frequency of less than 2 per 1,000 to 5.72. Syphilis, excluding neurosyphilis, essentially doubled in frequency over the previous year, showing an incidence of 12.15 per 1,000. Comparing overseas troops as a whole with those of the Zone of Interior, gonorrhea was more of a problem overseas (38.81 per 1,000) than at home (31.52) ; chancroid was overwhelmingly a disease of soldiers stationed abroad, 7.29 against 1.43 per 1,000; while syphilis, excluding neurosyphilis, was more frequently observed among domestic troops, 15.12 per 1,000 average strength for troops at home and 8.89 for those abroad.

Viral hepatitis was a problem in the European theater. Though serum hepatitis occurred rather extensively in 1942, the greatest problem was with infectious hepatitis which occurred mainly in troops operating in continental Europe , in 1944 and 1945. The number of admissions in 1944 was 4,330 (rate 2.58 per 1,000), and 20,575 admissions in 1945, a frequency of 8.67 per 1,000 average strength. For the 2-year period, 1944-45, combined deaths from serum and infectious hepatitis had ranked fifth among deaths from communicable disease in the theater, an average rate of 1.14 per annum per 100,000 average strength.

Data for scarlet fever and the partial information now available for streptococcal sore throat indicate that hemolytic streptococcal infections were


36

less prevalent among troops of the European theater than in continental United States, both regions being in the north Temperate Zone.

The malaria incidence rate reported in the theater, 4.88 per 1,000 for the 4-year period, was almost wholly relapse of original infections contracted in other theaters by troops transferred to Europe in connection with the major military effort of the final years of the war. There was little indigenous malaria.

The common communicable diseases of childhood recognized in the European theater were only a fraction of those reported for troops in the continental United States . Mumps was the commonest, as it usually is among seasoned troops. The report of more herpes zoster (1,295 admissions) than chickenpox (774 cases) is unusual.

That concern about communicable disease increases as a war ends is a principle of military preventive medicine. The venereal diseases illustrate this well, as do three other infectious diseases of this experience, typhoid fever, paratyphoid fever, and diphtheria. Both typhoid fever and paratyphoid fever were almost nonexistent in the early years of the theater-4 cases of each disease occurred over a 2-year period. In 1944, 25 cases of typhoid and 20 of paratyphoid occurred during active combat and field operations. The main trouble, however, centered about those spring months of 1945 which saw the end of hostilities. For the year as a whole, the number of cases of typhoid and paratyphoid totaled 35 and 60, respectively. The really serious problem, however, was among the prisoners of war (p.182).

Diphtheria in the European theater had much the same history. The first 2 years showed few cases, 27 and 45. During the third year, cases increased to 245, but 1945 produced an epidemic as troop strength was consoli dated in West Germany where the disease was highly prevalent in the civilian population. Admissions for the first 6 months of the year were at the rate of 0.60 per annum per 1,000 average strength; the rates were twice that during the last 6 months, 1.26 per 1,000.

The 10 cases of louseborne typhus fever in 1945 warrant little attention of themselves in the total account of communicable disease. The significance lies in that small number of infections among troops operating in a region where typhus fever was widely dispersed and broadly epidemic. Military preventive medicine has no finer accomplishment.

The principal cause of death from communicable disease in the theater was tuberculosis with a death rate of 4.41 per 100,000, in large part determined by the 6.02 rate of 1945, this in turn related chiefly to recovered prisoners of war. The death rate for tuberculosis was greater in the European theater than in others. For all troops overseas, deaths from tuberculosis were some 47 percent in excess of those for men stationed in continental United States .

Mediterranean Theater of Operations

The environment in which troops of this command were called upon to operate was one of the more difficult among American areas of influence; the


37

communicable diseases consequently occurred frequently. Incidence and death rates for tuberculosis were less than the average for all overseas troops; for pneumonia, they were somewhat greater. For malaria, the incidence rate was 42.68 per annum per 1,000 average strength, placing the theater fifth among the eight overseas theaters in incidence, and the death rate, was 3.84 per 100,000. Incidence was greatest in 1943, when the rate reached 71.84 per 1,000. During the 4 years of war, there were 63,292 cases of malaria in the theater.

Next to the Southwest Pacific areas, epidemic hepatitis was most prevalent in the Mediterranean theater. Data on admissions are available only for the last 2 years of the war: 18.16 per 1,000 average strength in 1944 and 19.88 for 1945. The death rate per 100,000 for the 2 years was 3.39 per annum, about one-half that for the combined Pacific theaters; in 1945 in the Southwest Pacific Area, admission rates reached 34.85 per annum per 1,000 average strength.

The venereal diseases were of more frequent occurrence in this theater than in any other. Rates were consistently higher than in Europe . For gonorrhea, the incidence rate of 66.42 per annum per 1,000 exceeded the rate for the European theater, which was 50.09. As in other theaters, rates rose at the end of the war; the main difference was that in the Mediterranean theater the rise started a year earlier. For chancroid, the 22.25 per 1,000 annual rate over the 4 years exceeded that for any other major command, as did the syphilis rate of 15.22, even though the latter rate was only fractionally greater than in continental United States .

The dysenteries were an outstanding problem. The rate for bacillary and unclassified dysentery combined was 6.43 cases per annum per 1,000 average strength; for amebiasis, the rate was 1.26. These three categories are only part of a larger group of acute intestinal infections described in detail in a subsequent chapter (p. 340).

The Mediterranean theater had a moderate poliomyelitis problem. Other theaters had somewhat greater incidence, notably the China-Burma-India theater with 0.18 per 1,000, compared with 0.09 for the Mediterranean area, and death rates were higher, China-Burma-India being 8.2 per annum per 100,000.In all, this theater had 127 cases of poliomyelitis during the 4 years.

Fungus infections and the intestinal parasites, while of some consequence, were measurably less significant than in the Pacific and China-Burma-India theaters. Sandfly fever was a special problem. Incidence rates were 7.56 per 1,000 strength witti a total of 11,206 cases, distributed with comparative regularity over the years of 1943-45.The theater was activated in late 1942, and only 11 cases occurred that year. There were no deaths in the total series of cases. The number of cases in the Mediterranean theater exceeded that in any other, but rates of incidence were only one-fourth those prevailing in the Middle East theater, a smaller command which had 4,399 cases.

The newer methods for control of louseborne typhus fever had their initial test in the Naples epidemic of 1943, and the principle was there estab-


38

lished that troops could operate with relative safety in typhus areas; the theater had only 16 cases during 1942-45.

The six leading causes of death due to infectious and parasitic disease were in the following order: Malaria with 3.84 deaths per annum per 100,000 average strength; tuberculosis, 3.51; infectious hepatitis, 3.39 (1944-45); poliomyelitis, 2.49; bacterial pneumonia, 1.89; and meningococcal meningitis, 1.35.

Middle East Theater

Tuberculosis was no particular problem in the Middle East theater; in fact, the record achieved there was better than in any other overseas command. No deaths were reported for nonpulmonary tuberculosis, which was unique among the nine major commands. This form of tuberculosis accounted for about a fourth of all tuberculosis deaths overseas and more than a third in continental United States .

The admission rate of bacterial pneumonia was the greatest of any theater of operations; the death rate, 2.05 per 100,000 strength, was second only to that of the China-Burma-India theater. No theater had the admission rate of continental United States for bacterial pneumonia, 2.54 per 1,000 strength. For all troops overseas, the admission rate was 1.26. Death rates for continental United States were 1.69 per annum per 100,000 and for overseas theaters 1.44.

The Middle East is notably a malarial zone, and incidence rates of 65.32 per annum per 1,000 over the 4 years were second only to the rate in the China-Burma-India region.

The dysenteries were extremely prevalent with a combined incidence rate of 21.76 for bacillary and unclassified dysenteric disease. Amebiasis reached the appreciable rate of 8.08 per 1,000, again second only to China-Burma-India. Food poisoning was prevalent in 1944.

The theater record for gonococcal infection was good, but chancroid was at high levels of 19.41 per 1,000; syphilis ranked well up among all major commands of the Army with a rate of 13.48. The incidence of lymphogranuloma venereum (1.94 per 1,000) was higher than in any other theater or area except the China-Burma-India theater.

The area, featured an incidence of 30.09 for sandfly or pappataci fever, the highest rate among commands by a large margin. Cases numbered 4,399. An individual theater characteristic was the presence of leishmaniasis with incidence of 1.93 per 1,000 and 282 cases reported. The disease appeared in 6 other theaters, and 22 cases are in the, records of coninental United States as first recognized there. In all, there were some 497 cases in the entire Army, with half of them in this small theater.

Poliomyelitis cases were 21, for a rate of 0.14 per 1,000, and 8 patients died.

The list of main causes of death from infectious and parasitic diseases departs greatly from any thus far noted. In order, they were malaria (8.21), poliomyelitis (5.47), and smallpox (3.42), followed by tuberculosis, bacterial pneumonia, and diphtheria, each with rates of 2.05 per annum per 100,000.


39

China-Burma-India Theater

The exigencies of war that required operation of foreign troops in the area included within the China-BurmaIndia theater brought all the support necessary to the emphasis placed by military medicine on the communicable diseases. To those not previously acquainted with this general region, realization comes quickly that there are parts of this universe in which the communicable diseases certainly are not conquered.

First consideration is given to those two communicable diseases which are responsible the world over for most deaths and disability and which are still to be found in almost any list of 10 leading causes of death. Tuberculosis and pneumonia are well represented in this present experience of World War II in the Far East . The admission rate for bacterial pneumonia was third among theaters of operations, preceded by the Middle East and Mediterranean areas. The death rate, however, was measurably in excess of any other and indeed was close to twice that of continental United States , which, as will be recalled, was itself greater than for the theaters, all troops outside continental United States .

The incidence rate for tuberculosis, all forms, was 0.98 per 1,000 average strength compared with 0.92 for all overseas troops and 1.48 for the United States . Death rates per annum per 100,000 average strength were 3.88, similar to the rate for all units serving abroad (3.87) but higher than in the United States (2.64).

The theater had its difficulties with the venereal diseases. The incidence of gonorrhea was satisfactorily low, well below average for troops at home or abroad. Lymphogranuloma venereum, however, had the highest incidence rate among theaters or the Zone of Interior with a rate of 2.50 per 1,000. Syphilis was well above average for soldiers serving abroad and so was chancroid, each by about one-half.

The theater had the top malaria rate among major commands with an incidence of 86.70 per annum per 1,000 over the war period.

The intestinal infections were uniformly frequent.Typhoid fever totaled 78 cases and paratyphoid 96. The incidence of dysentery, as judged by data for bacillary and unclassified forms but far from a complete rate, was 21.19 per annum per 1,000 strength; the Middle East being the only close rival. Amebiasis had the extreme rate of 23.95 per annum per 1,000; not even the Middle East offered any sort of competition and the Southwest Pacific was in third place with 6.67 per 1,000.

The highest incidence of poliomyelitis among theaters was in China-Burma-India, and the disease in general was more, frequent abroad than at home. The general list of parasitic diseases was enhanced in frequency, and no theater had more fungus infections. Complete data for hepatitis are not at hand, but those available indicate the disease occurred at close to average level for troops of all theaters.

The China-Burma-India theater had its individual problems. Sandfly fever was a fairly common disease with 2,941 cases giving a rate of 6.71 per


40

1,000. Dengue fever was variously epidemic, especially in 1943 and 1944. Cases totaled 8,217, and average annual rates over the 4 years were 18.74 per 1,000. Scrub typhus enters the list of diseases thus far recorded with 804 cases, the incidence rate 1.83 per 1,000. The average annual death rate for scrub typhus in the China-Burma-India theater topped that of any other communicable disease in any theater of World War II.

That the infectious and parasitic diseases need to be judged in terms other than those referable to the United States is well demonstrated by the principal causes of death among diseases of this class as recorded in this Far Eastern experience. First on the list is scrub typhus, 14.60 deaths per 100,000 troop strength. Next in order are malaria, 9.12; poliomyelitis, 8.21; smallpox, 4.56; tuberculosis, 3.88; bacterial pneumonia, 3.19; and meningococcal meningitis, 2.05. The items included and the values themselves are rather startling. For a number of these diseases, sharp irregularities in annual rates of occurrence mark the coming and going of epidemics.

Southwest Pacific Areas

The part of the world that includes the Southwest Pacific areas rivals the China-Burma-India area in frequency of communicable disease; if anything, the variety is greater. This Army area had a part in the influenza of 1942. Tuberculosis and bacterial pneumonia were at average levels for overseas troops. The record in respect to the venereal diseases was good, even for lymphogranuloma venereum and chancroid, which was a creditable achievement in this environment.

The main difficulty was with malaria, for the theater had an average of 57.07 cases per annum per 1,000 average strength during the war period. No less than 104,809 cases are included in the medical records of the command. A proverbially endemic disease, malaria was epidemic in 1943 when the incidence rate for the year reached 209.56 per 1,000 strength. Energetic control measures resulted in a wholly satisfactory record the next year and a low 33.58 in 1945.

Mumps, as would be expected, was first among the common communicable diseases of childhood, but a moderate epidemic of rubella in 1942 was an unusual event which carried into the following year. An epidemic of diphtheria, 505 cases, occurred in 1945.More cases of poliomyelitis (224) were reported than from any other theater, the incidence being 0.12 per 1,000 average strength.

The full data on infectious hepatitis are not available, but the 36,110 admissions in 1945, making a rate of 34.85 per 1,000, was not duplicated in any theater during this or the preceding year. Even in 1944 in this theater there were as many as 4,966 cases, the rate being 9.21. In the Southwest Pacific areas, deaths due to infectious hepatitis averaged 8.44 per annum per 100,000 during 1944-45.

Leishmaniasis with 29 cases, 5 cases of rabies, 70 of arthropodborne encephalitis, and 20 cases of yaws gave variety to the larger events just recorded.


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Deaths per annum per 100,000 average strength for the Southwest Pacific Area gave first place among infectious and parasitic diseases to scrub typhus (11.43), followed by infectious hepatitis (8.44 for 1944-45), malaria (6.15), poliomyelitis (3.81), and tuberculosis, all forms (3.71).Bacterial pneumonia (1.52) was not within the first five. The list is as bizarre as that of the ChinaBurma-India theater to those who are accustomed to western public health problems.

Dengue fever was another prevalent disease of the Southwest Pacific. A total of 50,903 cases occurred; the over-all annual incidence rate for 1942 to 1945 was 27.72 per 1,000.The, epidemic year was 1944 with 28,292 cases and an annual rate of 52.47; 1942 had rates even higher, but fewer numbers were involved. Only a favorable situation in 1945 permitted the average rates cited.

The dysenteries were commonly present as would be anticipated. Bacillary and unclassified dysentery together gave a total theater rate of 9.73 per annum per 1,000. Amebiasis had a rate of 6.67 with some 12,244 cases reported; most of them, 11,475, occurred in the final year of 1945, with the evident implication that actually there had been more cases in other years than had been recognized. Typhoid fever accounted for 73 cases, and paratyphoid fever for another 183 cases. Food poisoning was more common than for overseas troops in general.

Scrub typhus was a special feature of communicable disease occurrence in this theater. Of 5,436 cases reported from all theaters of operations, 4,459 were in the Southwest Pacific, average annual rates being 2.43 per 1,000. Fleaborne typhus was present to the extent of 87 cases, but there was no louseborne typhus.

The parasitic diseases were common, particularly hookworm and ascariasis. There were some 323 admissions for filariasis, 233 of them in 1944; over-all theater rates were 0.18 per 1,000. Schistosomiasis accounted for 1,545 cases, rate 0.84, with 1,460 cases in the single year of 1945. Fungus diseases were as abundant as in the China-Burma-India theater.

Central and South Pacific Area

The health record established by this area in respect, to the venereal diseases was outstanding; it was second only to the record in the North American area and was far better than that of continental United States . The incidence rate for gonorrhea was 10.87; for syphilis, 3.64; chancroid, 1.91; and lymphogranuloma venereum, 0.33 per 1,000 average strength; in each instance, with the exception of chancroid, markedly below the average for troops overseas (table 10) or at home.

The incidence rate for tuberculosis was about equal to the average rate for overseas troops, but the rate for bacterial pneumonia was lower than rates for all other overseas areas.


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As in the Southwest Pacific Area, malaria was the main problem, and the history of events was much the same in the two theaters. During the first year, the number of cases was small because of the limited time of exposure and the small troop strength, but in 1943 cases numbered 55,050 and the rate per 1,000 was 188.81, not dissimilar to that of Southwest Pacific in the same year. The recovery was more prompt, however, for the incidence rate in 1944 was 24.33 and the last year of the war had the excellent record for that locality of 22.48 per 1,000.

The intestinal infections were the next broad problem. The dysenteries of recognized form, bacillary and unclassified, prevailed in a frequency of 5.58 per 1,000; the main difficulty appeared in the initial year of 1942, and progressive improvement thereafter gave a rate in 1945 of 3.43 per 1,000. Food poisoning was of noteworthy frequency in the years after it was established as a reportable condition; in 1945 there were 1,205 admissions and a rate of 3.21 per 1,000.Amebiasis (rate 2.50) was less commonly recognized than in the Southwest Pacific (rate 6.67 per 1,000). Typhoid and paratyphoid fever fever cases were 28 and 33, respectively.

In the Central and South Pacific area, dengue came close to matching its behavior in the Southwest Pacific, rates for the Central and South Pacific being 23.83, and in the Southwest Pacific 27.72 per 1,000. The disease was epidemic in both 1943 and 1944, a total of 28,092 cases being reported during the 2 years.

Although the incidence of infectious hepatitis was heavy, it was much lower than in the Southwest Pacific. Both parasitic and fungus diseases were prominent. There were 171 cases of scrub typhus, but this disease was of no significance here compared with the other Pacific theater; fleaborne typhus was more frequent than in any other theater, but there were only 123 cases.

This theater was characterized by the preponderance of filariasis; 1,348 admissions were reported, most of them in 1943 and 1944. The Southwest Pacific had far less, but even in the Central and South Pacific the rate was only 1.07 per 1,000 average strength. The 116 cases of schistosomiasis were a minor event in comparison with the observed frequency of that disease in the Southwest Pacific Area. It was in this area that one of the two admissions for glanders in foreign theaters was reported, the other being in the Middle East theater.

Diphtheria appeared in minor epidemic proportions in the last 2 years of the recorded period.

The six leading causes of death due to infectious and parasitic diseases in this theater during 1942-45 were tuberculosis, all forms (3.66), malaria (3.50), infectious hepatitis (1.96 for 1944-45), bacterial pneumonia (1.11), poliomyelitis (0.48), and meningococcal meningitis (0.40). These rates are expressed in terms of number per annum per 100,000 average strength.


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Latin American Area

The Latin American area was in a tropical and subtropical region on the other side of the world from the two Pacific theaters. Comparison is scarcely productive for the theater was small and singularly free from combat action and the associated field conditions. The incidence of communicable disease and the deaths from infection are instructive in respect to what can be accomplished with modern preventive services under environmental conditions that provide more than usual risk.

Tuberculosis death rates and the incidence and death rates for bacterial pneumonia were favorable; these two communicable diseases lead almost all other infectious processes in temperate zones as causes of death and rank high almost everywhere.

Incidence of the venereal diseases was high. Gonococcal infection ranked close to the top for all theaters, and occurrence of syphilis was much above the average. Chancroid was at, the high level of 12.19 per 1,000 strength, and lymphogranuloma venereum had a rate of 1.60 per 1,000, three times that for theaters in general and more than twice the home incidence. One peculiarity marked this experience in control of the venereal diseases. The usual pattern is one of initial difficulties, subsequent improvement in rates until the war ends, and then an incidence even greater than before. The Latin American area, after having had consistently high rates throughout the war, ended with a marked improvement in 1945 for all of the four diseases mentioned.

Malaria was also prominent among the problems of this theater. The total wartime experience ended with a rate of 41.01 per 1,000 per year, but the first year was responsible for most of this with an annual 1942 rate of 99.78. The improvement that followed was remarkable, and 1945 ended with an incidence rate of 8.17 per 1,000 average strength.

Intestinal infections were at high risk, but the rate for recognized dysenteries was good, 1.72 per 1,000 per year. Parasitic infections were relatively frequent among infections as a whole. Ten cases of typhoid fever occurred and seventy of paratyphoid. Infectious hepatitis was at a low level.

A series of epidemics of rubella was an unusual occurrence, the annual rate for the 4 years being 5.14 per 1,000, with 9.82 in 1945. Only in continental United States was this disease relatively so prevalent; in the Latin American area, rubella exceeded both mumps and measles.

Poliomyelitis was represented in this theater by 13 cases and 3 deaths for the 4 years. The theater had 1 of the 6 cases of rabies in overseas theaters. Sandfly fever provided a minor problem with 35 cases.

The deaths from infectious and parasitic disease in the Latin American area are again a curious collection as judged by conditions in continental United States for they rank in order as follows: Malaria, 4.72 per annum per


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100,000 average strength; tuberculosis, 2.63; bacterial pneumonia, 0.79; and poliomyelitis, 0.79.The values themselves are notably low.

North American Area

Of all major commands, this small theater had the best record for death and disability from disease, all forms, and from communicable diseases; indeed, the theater far outdistanced all others. The venereal diseases were at an unbelievably low level, uniformly for all major categories and throughout the 4 years. The usual increase in the last year of the war occurred here but served only to bring the rate for gonococcal infections to 10.43 per annum per 1,000 and for syphilis to 3.97.

The 1942 and 1943 experience with influenza was much the same as in all theaters, but the disease continued through 1945 as the most frequently occurring item of the infectious and parasitic list, in all 6,165 cases. Bacterial pneumonia was infrequent.

A small outbreak of meningococcal meningitis in 1943 was one of the few epidemic events.There is little to note but a good record.

Causes of death from infectious and parasitic disease were tuberculosis, all forms, 3.46 per annum per 100,000 average strength; hepatitis, mainly serum hepatitis of 1942, 2.64 (on the basis of 13 reported deaths, 11 for 1942) ; meningococcal meningitis, 1.02; bacterial pneumonia, 0.81; and influenza, 0.61.

Distribution by Mode of Transmission

The mechanisms by which an infectious agent is transported from reservoir to susceptible human host are a fundamental factor in designing methods for the control of the communicable diseases. Modes of transmission serve as a logical means for classification of these disease processes. Table 12 shows cases of infectious and parasitic diseases, by mode of transmission.

Among troops in the continental United States the incidence rate for infectious diseases transmitted chiefly through the respiratory tract was more than two and one-half times the rate for all overseas areas. The Far East and Pacific theaters had notably low rates, with other theaters occupying a middle position except for the North American theater which had rates of 26.13 per annum per 1,000 average strength. It is reaffirmed that common respiratory disease is not included.

Intestinal infections showed greater variation between theaters than did the respiratory infections. The rate for Zone of Interior troops was 1.86 per annum per 1,000 compared with 9.47 for all troops overseas. The European and the North American theaters lead good rates, equal to or below those of continental United States . This circumstance, along with correspondingly low rates for arthropodborne infection, accounts in large part for the over-all good record of these two theaters. The annual incidence of 0.84 per annum per 1,000 for intestinal infections in the North American theater is in contrast


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TABLE 12.-Incidence rates for infectious and parasitic diseases in the U.S. Army, by mode of transmisson and theater or area of admission, 1912-151

to the 49.16 of the China-Burma-India theater. Other tropical areas also had high levels of intestinal infection; the rates of the Mediterranean and Central and South Pacific theaters deserve commendation considering the environmental conditions under which troops operated.

The venereal diseases have been compared in discussion of the theaters. Scabies is the main component of contact infections listed as "others."

Malaria mainly determines the extent of the arthropodborne group of diseases; one-fourth of mankind lives in malarial zones and United States Army troops were engaged in most of the places where malaria flourishes.Dengue and sandfly fever were other important elements. Malaria and scrub typhus were the chief contributors to the number of deaths.

Epidemic hepatitis was the important disease in the class of infections where mode of transmission remains uncertain, notably so when serum hepatitis is included as in this instance. In general, the incidence rates, shown in table


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12, are representative of infectious hepatitis (including some serum hepatitis), since the incidence of the other three diseases in this category (infectious mononucleosis, acute poliomyelitis, and lymplrocytic choriomeningitis) was relatively low.

INTERNATIONALLY QUARANTINABLE DISEASES

Never in the history of warfare has an army traveled so far or so widely as did troops of the United States during World War II. Never before has an army been called upon to take up occupational duties in such farflung parts of the world. No recognized focus of the great pandemic diseases of history was untouched by American interest and influence nor unvisited by American soldiers.

Not only was the amount and extent of travel by United States Army troops greatly increased during the war, but it was potentially more dangerous travel. Compromise of established measures for international quarantine is unavoidable in time of war. Civilian health staffs of countries at war are depleted. Necessary supplies for prevention and control of disease among civilian populations are directed in considerable part to military needs. Newly developed methods are at the first disposal of the military. Port control in invaded countries was invariably taken over by the occupying enemy forces; when these areas were liberated, port sanitation was usually found to be totally disorganized. Many ordinary regulations and procedures in respect to air and sea traffic were abrogated or modified because of military necessity; others were disregarded through license, ignorance, or exigency. There was a greater potential health risk in international travel during the war and greater possibility of the spread of the quarantinable communicable diseases. The record was astonishingly good. It will now be considered having been purposely avoided in the presentation of problems of individual theaters.

The six internationally quarantinable diseases are cholera, plague, yellow fever, louseborne typhus fever, louseborne relapsing fever, and smallpox. In World War II, 3 of the 6 (cholera, louseborne typhus fever, and smallpox) definitely appeared in various major commands of the Army. In addition, it is possible that some of the relapsing fever cases were louseborne. No case of yellow fever or plague was reported; in fact no plague-infected rat was found in an American ship. The data for the Army as a whole and according to theaters of operations are given in table 13. The four diseases, cholera, louseborne typhus, relapsing fever, and smallpox, accounted for 402 cases and 32 deaths among troops of the Army as a whole. All theaters and areas had some experience with at least 1 of the 4 diseases. The China-Burma-India theater had experience with all four.

Relapsing fever was of commonest occurrence, for it appeared in home troops and in all theaters with the single exception of the European theater. There were no deaths. The Mediterranean theater accounted for 49 cases, an admirable record in view of the extensive epidemic that occurred in the


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TABLE 13.-Internationally quarantinable communicable diseases, U.S. Army, by theater or area, 1942-45

civilian population of the area. The greatest number, 70, was in the ChinaBurma-India theater; aside from 28 cases in the United States and 13 cases in the Middle East, the remainder was scattered sporadic infection.

Smallpox was next in frequency, with 117 cases and 30 deaths. The number of deaths indicates that the disease in most instances was variola vera and not the alastrim variety which characterizes smallpox in the United States and of which there were 6 cases in this military experience. All others were in theaters of operations.China-Burma-India had 33 cases and the 2 Pacific areas almost equal numbers. Only the European and North American areas had no smallpox.

The limitation of louseborne or classical typhus fever to 104 cases and no deaths was one of the remarkable achievements of preventive medicine in World War 11. The infection was introduced into 5 of the 8 theaters. The potentiality for a major epidemic was great, for the existing circumstances were not dissimilar from those of other wars whose outcome typhus fever so frequently has decided. In World War 1, 1914-18, and the immediate period thereafter, more than 5,000,000 persons had typhus fever in Russia alone, and deaths have been estimated at 2,000,000; in Serbia, essentially one-fifth of the


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population was involved in a typhus epidemic, with 150,000 deaths in a 6-month period in 1915. In the European theater, in this war, American troops entered a region in Germany that had at the time about 17,000 cases among the civil population and displaced persons. The United States Army escaped with 10 cases and no deaths.

Cholera under ordinary circumstances is endemic only in the China-Burma-India theater among the eight principal divisions of territory its which the United States Army operated overseas. The disease has great potentiality for spreading; it has repeatedly ranged far afield from this endemic focus and on several occasions has invaded continental United States in epidemic proportions. Ten cases of cholera occurred among American troops of the China-Burma-India theater with two deaths, a usual fatality for cholera. There was much cholera in both India and China during the war years and in the particular places where troops were stationed. The disease did not spread within the command not to neighboring theaters.

The great quarantinable diseases have settled marry wars. All but two of them invaded one or more of the great command areas; no theater escaped visitation by at least one of them. None gained a foothold. The risk was real. Here then is further justification for the emphasis on communicable diseases in military preventive medicine.

INFECTIOUS AND PARASITIC DISEASES OF ESSENTIAL MILITARY SIGNIFICANCE

The close relationship of communicable disease and military operations has been so long recognized, so decisive in military history, and so stressed in military planning as to be accepted doctrine. The seriousness of a given disease in respect to death and disability may be the issue.A relatively mild condition may attain importance because of the noneffectiveness it engenders. Much depends on the nature of existing military operations. In this war, an outbreak of mumps had disorganized a training program. Epidemics of acute upper respiratory infection complicated movements of troops on long long journeys. An undue prevalence of so benign a disease as scabies interfered with preparations for marshaling an invasion. Dysentery disrupted a campaign, and the German general staff could speak feelingly of epidemic hepatitis its Africa . Typhus fever threatened again to settle the outcome of a war to become, as Hans Zittsser has remarked, a more potent influence than generals.

The communicable diseases transmissible by way of the respiratory tract fall into two main groups, those involving the respiratory tract itself and those leading to general infection with various localization. The first group always has importance.

Fortune favored this war in respect to influenza. The disease was present in excessive amount in 1942 and 1943. Influenza A was pandemic in proportions but mild in form. This was a major consideration in the uniformly favorable rates for bacterial pneumonia, with the odd result, however, that


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deaths from this cause were more frequent among the military populations stationed in warm climates, such as China-Burma-India with 3.19 per 100,000 and the Middle East with 2.05, than in the temperate zones of continental United States and the European theater, which reported rates of 1.23 per annum per 100,000.

Tuberculosis failed to maintain its established place as a cause of death and disability in military populations because of the effective screening of recruits at the time of induction.

The diseases of the respiratory group leaving localization other than in the respiratory tract itself failed to reach the statistical expectancy warranted by experience of previous wars. Mumps, the usual leader in numbers of cases, was outdistanced by rubella. The incidence of mumps was considerably lower than it lead been in World War 1, while the rubella rate was slightly higher. The incidence of meningococcal meningitis, justifiably recognized as a military disease, was only 0.51 per annuum per 1,000 for the, total Army and 0.67 for continental United States .

The record for intestinal infections was remarkably good, considering the long history of these diseases as the primary concern of camp and field. During the 4 years of war, the European theater had only two deaths from bacillary and unclassified dysentery combined, and operations were on a battleground where thousands have died of this cause in other wars.

Typhoid fever illustrates the effect of environment in the face of similar methods of prevention and control; 91 cases occurred in continental United States and 414 overseas, with rates of 0.01 and 0.04 per 1,000 average strength. The death rate for typhoid fever was relatively much greater in foreign operations, for 3 deaths occurred among home troops and 33 overseas.

Amebiasis was more costly in this war because of the many tropical areas in winch troops operated; the same is true for infections by intestinal protozoa other than Entamoeba histolytica. The disability engendered through food poisoning cannot be well determined from the existing data, for food poisoning was not reported as such until 1944, and even then acceptance of the new direction for reporting was not immediate; previously, cases were usually included among the diarrheas and dysenteries. Indication is that this condition continued as a common cause of disability, despite the improvements in camp sanitation and nutritional practices.

The data cited in table 12 and the accounts of individual theaters show that the venereal diseases were still a main feature of medicomilitary practice; the records were better than in some outer wars, but much remains to be done before control can be considered adequate or satisfactory.

Fungus infections took on new importance with operations in tropical countries, where mycosis of the feet interfered with military effectiveness and specific fungus infections were relative frequent. Coccidioidomycosis was a special problem of troops in the United States .

Schistosomiasis and filariasis were military infections new to most military physicians of this war and were responsible for much disability before control


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was effected. Scabies, that common accompaniment of troops, had an interesting history in that admission rates progressively increased as the war continued; 1942 had a rate for overseas troops of 2.03 per 1,000 which increased in successive years to 2.84, 3.08, and 5.48. At home, rates were similar to those overseas, although the spread between first and final years was greater for domestic troops, the rates being 2.38 in 1942 and 7.60 in 1945. The experience of the United States Army in World War I was repeated in World War II, and the problem of prevention of scabies still remains unsolved. Progress has been made, however, in the control of infestation by lice. Admission rates were 0.32 per annum per 1,000 in continental United States and 0.18 overseas. The degree of louse infestation in the American Expeditionary Forces in 1918 was estimated to be 1 to 2 percent, but the significant feature is that in both regions rates declined in the same progressive fashion as they rose for scabies. The new insecticides give improved methods for control.

The arthropodborne diseases introduced a fresh element into historical United States military practice. Malaria was the chief problem. Troops had of course operated before in malarious regions and had developed effective control, for instance, in Panama . A new situation was encountered, however, when field operations had to be carried on both in unfamiliar environments and in many places where malaria was hyperendemic. The initial costs of this disease were heavy, but the final results were good. Filariasis, scrub typhus, and sandfly fever also posed relatively new problems. Dengue had almost been forgotten, especially the fact that it could reach such epidemic proportions as developed in the Pacific theaters.

Infectious hepatitis has had a part in war before but never to the same extent as in World War II, in which was added the further complication of serum hepatitis.

The results attained in control of tetanus, a disease long recognized as a peculiar hazard of war, are so striking as to deserve special mention. In the European theater where battle casualties were more numerous than in any other theater, both the mortality and the morbidity rates were approximately the same as those for troops stationed in continental United States, thousands of miles from a battlefield. The almost unbelievably good results, a single case and a single death during the whole period of operations in Europe , are attributable to the remarkable effectiveness of active immunization brought about by tetanus toxoid. Eight cases in the Zone of Interior were related to tetanus infection among recruits, principally before immunization had been accomplished. Only four cases of tetanus occurred among all troops overseas.

ACHIEVEMENTS AND CHALLENGES

Many new problems come to light in the course of an experience as broad as that described in this chapter. The development of administrative measures and the search for new knowledge on which those measures depend account for much of the effort expended on scrub typhus, plague, schistosomiasis, infectious


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hepatitis, and the arthropodborne encephalitides. The story of the achievements of the war years fills many pages in these volumes on infectious diseases. The stimulus continues. No one of these problems was wholly solved but what was learned serves as a useful guide to the research of the postwar years.

Fort Bragg fever and Bullis fever, diseases newly recognized in the course of the war, were of minor military significance but were biologically informative. For instance, Fort Bragg fever was eventually found to be a form of leptospirosis. Clinical variants and immunological differences among older established processes were better defined. Numerous problems suggested by this experience are as yet scarcely touched.

Infectious mononucleosis was a fairly frequent disease among troops, 13,571 admissions in continental United States and 4,961 abroad. A significant feature was that rates rose each year for both great groups of troops, in the United States from 0.29 in 1942 to 1.71 in 1945, and overseas from 0.23 to 0.58 per annum per 1,000 average strength.

Lymphocytic choriomeningitis was present among domestic troops to the extent of 333 admissions in the last 3 years of the war, data being unavailable for 1942. Overseas troops with this infection numbered 425 for the same 3 years, 260 leaving occurred in 1945, primarily in Europe and the Mediterranean areas, but with all theaters represented, even the exemplary North American area. The disease is worldwide in its distribution, and, with due allowance for unconfirmed diagnosis, seemingly more frequent than ordinarily recognized.

The behavior of herpes zoster and chickenpox in this group of young adults, both at home and abroad, warrants further analysis. Like other communicable diseases of childhood, chickenpox is a fairly frequent infection of troops, especially recruits, less so than mumps and measles but more than whooping cough. Among troops stationed in continental United States , 8,555 cases of chickenpox occurred, but the returns also give 5,384 admissions for herpes zoster. Compared to continental United States , chickenpox was one third as frequent among overseas troops, but herpes zoster occurred more frequently. Overseas, the 2,109 cases of chickenpox were exceeded by the 4,735 admissions for herpes zoster.

World War 11 involved more men and extended over a wider geographical area than any other war in history. The successful result that accrued to American arms was influenced in forceful degree by favorable casualty rates for the communicable diseases, rates that have no precedent.

The actual experiences of this war justify the firm emphasis which military medical officers continue to place on the significance of the communicable diseases. These experiences included the repeated threat of the great pandemic diseases; the occurrence of epidemics oven under the best of conditions; and the strange problems brought by modern warfare, characterized as it is by rapid movement and wide dispersal of resources. Well-known infectious diseases, typhoid fever for example, carefully evaluated and adequately controlled under conditions of the American environment take on new significance when encountered in other parts of the world.New diseases come to light, and old


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ones present new facets. Perhaps the most important consideration of all is the steady erosion of manpower brought about by everyday infections, losses which become evident when communicable disease is measured in terms of non effectiveness and of the permanent injury which leads to lasting disability. The deaths that these diseases cause are not the sole concern, nor do they always provide a reasonable basis for judgment, in both the military and civilian practice of medicine and public health.