INTRODUCTION
CHAPTER I
GeneralConsiderations of Modes of Transmission
John E. Gordon, M. D.
The control of communicable disease remains the basicactivity of military preventive medicine. Preventive medicine had its origin inthe control of communicable disease and for many years was largely restricted tothis field. As reasonable and useful additions were made to the program forprevention, the infections came to have relatively less emphasis, but the totaleffort expended in their control is still much the same. The typicalorganization of preventive services at the combat level in World War IIconsisted of a section each on epidemiology, venereal disease control,nutrition, and sanitation. Two of the four sections were wholly concerned withthe control of communicable diseases, and the other two lead much to do withlimiting the spread of infection. Comprehensive programs were planned by theOffice of the Surgeon General and the theater commands, but the outstandingactivity was still the control of communicable disease.
Programsof prevention have been broadened materially in the course of years to includebattle casualties and nonbattle injuries as well as disease--the threerecognized classes of death and disability in military practice. A refinedknowledge of wound ballistics has led to major developments in body armor andother protective devices, along with changes in schemes for evacuation of thewounded. Nonbattle injury has superseded disease, including communicabledisease, in importance as a cause of death in the Armed Forces in both peace andwar, with the result that traumatic injury of accidental origin and poisoningdue, to alcohol and to other toxic agents take a rightful place in preventiveprograms.
The concept of prevention of disease itself also hasenlarged. Military medicine has had a leading part in the development of thescience of mental health. Nutrition is recognized as a primary feature ofpreventive medicine. Occupational medicine originally attracted attention whenit was restricted to industry, in which the Armed Forces have many interestsrelated to the production of armaments; now it has become a matter of concernwith respect to the health hazards which arise through the specific occupationof a soldier. Noninfective mass disease is not neglected, although conditions ofthis class have less significance in the Armed Forces than in a generalpopulation because the bulk of a military population is in the younger agegroups.
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The continuing emphasis on communicable disease in theorganization of military preventive services and in the underlying policies ofmilitary physicians holds in spite of a generally appreciated andwell-documented decrease in deaths from communicable disease in theUnited States and in many other countries. Progress is most definite in nations of theWestern World, but even there a measurable irregularity exists with respect tothe various specific infectious processes. The development of antibiotics andthe expansion of chemotherapy are a main influence in the lowering of thefatality rate; another influence is the lesser frequency of cases and hence thelowering of morbidity rates. The opinion is increasingly heard in generalmedical circles that the problems of communicable diseases are largely of abygone day and that infections are now so adequately controlled that eradicationin many instances is just around the corner. The military appraisal thatcommunicable disease is far from being conquered presumably has justification.Militarydecisions of strategic nature rarely are made without a sound marshaling offacts.
COMMUNICABLE DISEASE IN MILITARY PRACTICE
A possible explanation of the emphasis on the communicablediseases in military preventive medicine is that military operations provide asituation different from that of civilian existence. Certain communicablediseases are in fact recognized as peculiarly military diseases, the diarrheasand the dysenteries and epidemic hepatitis being typical examples. Hemolyticstreptococcal infections are frequently exaggerated in populations of youngadults, such as an army. The common communicable diseases of childhood-mumps,measles, and the rest-always have been more of a problem under militaryconditions than in civilian life.
Thepotentiality of epidemics for a variety of diseases conceivably may be greaterunder military conditions, or the risk of epidemics may center peculiarly inthose infections collectively grouped as the internationally quarantinablediseases (smallpox, plague) which flare up into world disaster because of theconditions of war.
The nature of an army population may be a decisive factor;military populations are young populations reasonably envisaged as having morethan their share of infectious disease as compared with a general population.
The military physician, in developing his opinion ofcommunicable disease, also may employ criteria other than those usual incivilian health practice, or he may have information not ordinarily available.For years, the costs of the communicable diseases have been measured in terms ofthe deaths they cause, largely by necessity, for the information on deaths ismore complete and more reliable than that for incidence, length of disability,or residual defect. Morbidity reporting has never reached a satisfactoryperformance 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 afar-reaching effect socially, economically, and medically, have little or nofatality rating. And, for those infectious diseases which are frequently fatal,morbidity rates supplement the knowledge derived from death rates. Thepractitioner of military preventive medicine has at his disposal information onmorbidity of a quality not available in any other social organization; recordsof admission to hospital and quarters are a part of the military system. Thesedata permit sound evaluation of noneffectiveness and of the reasons fordischarge for medical disability. In military practice, both considerations areimportant, but no more so than in civilian practice.
The daily noneffective rate, that is, the number of menabsent from duty, is an index of practical usefulness to physician and commanderalike, for it measures, in part, the fighting efficiency of an army. It isa measure of disability; it is a measure of morbidity as contrasted tomortality; and, since an account is required of each man on the roster, it hasunusual precision.
Froma military standpoint, the loss of a man through discharge for permanentdisability is equally as significant as a loss by death. In bothinstances, the Armed Forces are permanently depleted. The records of theselosses are likewise complete. The costs of communicable disease are thusdetermined in terms of death, disability, and defect; that is, in terms of totalcost. To evaluate the total cost of communicable disease is an endeavorincapable of practical fulfillment under conditions other than those of militarypractice. In the Army, judgment of a communicable disease and of communicablediseases in general thus rests on a broader base. A part of the optimism aboutcontrol of the communicable diseases seemingly depends on opinion derived mainlyfrom the number of resultant deaths, too little weight being placed ondisability and permanent defect resulting from these diseases.
Newer and improved methods of mass control and clinicalmanagement have led to gains in the control of communicable diseases which aremore or less evident everywhere. These gains are far from being evenlydistributed, however. Within countries and between countries, economic andsocial conditions have limited the application of the newer and improvedmethods; a deficiency in medical facilities and professional training issometimes 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 thatprocedure becomes more complicated or suffers in efficiency. At any rate, inlarge areas of the world containing the greater part of the human population,the, communicable diseases are still the main health problem. Modern war callsfor troops to operate in these regions. The different environment and thegreater seeding of infection may well lead to a poorer result in the control ofcommunicable disease, even when Americans are managed under American methods.
Forthese and other reasons, the Army experience, in which more than 10 millionAmericans served under conditions foreign to their usual environment
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and mode of life, affords an opportunity to measure more accurately theextent of the progress that has been made in the control of communicabledisease.
To look upon the communicable diseases as being now undercontrol is at best provincial. Proof that they are under control scarcely existsso far as theUnited 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 singleepidemiologic universe. Opinion concerning progress in the control ofcommunicable diseases is too frequently based on deaths alone, an incompletemeasure. Disability and residual defect are other primary considerations; goodexamples of diseases in which these two considerations are particularlyimportant are acute upper respiratory infections and modern scarlet fever,respectively. That progress has been made in the control of communicablediseases is evident; conclusions on the extent of that progress are too oftenextrapolated beyond the existing evidence.
The record of the behavior of the communicablediseases in World War II is presented in this and other volumes of thepreventive medicine series of the history with the primary purpose ofdemonstrating how much of a factor those diseases were in the conduct ofmilitary operations at that time. A secondary aim is to define those particularfeatures which characterize the communicable diseases in military practice ascontrasted with usual civilian conditions. The experience of this war wascomprehensive, without parallel in the history of warfare. Similar methodsand the same general policies were employed under a wide variety ofenvironmental situations, from the Tropics to the Arctic. Conceivably, this experience may lead to an improved evaluation of the placeof the communicable diseases in the public health practice of today. The firstconsideration is the system of classification of military casualties.
Classes of Military Casualties
Military casualties are divided into the following threecategories:Battle casualties, nonbattle injuries, and those the result of disease. Diseaseis thus set apart from injury as a source of disability. Injury is furtherbroken down into injuries of battle origin and those of noncombat origin.The classification of disabilities is generally clear cut but is sometimesarbitrarily made. For example, trenchfoot contracted in the line is classifiedas a nonbattle injury. Furthermore, similar disabilities may be classifiedas battle or noncombat in origin, depending on the circumstances under which theinjury was sustained. A gunshot wound of the hand incurred accidentally in atraining area or self-inflicted anywhere is a nonbattle injury and is distinctfrom the battle injury in which the same kind of wound results from contact withthe enemy. The definition of terms that follows is taken from War DepartmentArmy Regulations No. 40-1080, dated 28 August 1945.
Patients are classified according to the primary causeof initial admission, and their cases are reported in one of the following threecategories: Disease, nonbattle injury, or battle casualty. In instances ofpatients suffering from
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both disease and injury at the time of initialadmission, the most serious condition present is taken as the primary cause ofinitial admission and determines the classification. Patients admitted fora battle casualty and a disease or injury are classed as battle casualties.Thus, both primary and secondary diagnoses must be taken into account indetermining the frequency of any particular condition, such as one of thecommunicable diseases.
Allcases other than those due to injury or battle casualty are classed as disease.Included among the disease cases are those of patients suffering from reactionsto medication other than acute poisoning, those of patients admitted for thesequela of an injury they had incurred before entering service, and those ofpatients readmitted for the results of a traumatism (battle or nonbattle)incurred during service.
Nonbattle injury includes traumatisms outer than thosedefined as battle casualties. Traumatism refers to morbid conditions due toexternal causes. The term is applied to acute poisoning, except foodpoisoning, and to the results of exposure to heat, cold, and light as well as tovarious 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 orotherwise or is sustained by an individual while he is immediately engaged in,going to or returning from, a combat mission. It does not include traumatismsoccurring on purely training flights or missions. Psychiatric cases occurring incombat are not reported as battle casualties.
The measurement of losses from whatever cause is accomplishedby computation of rates that relate to three principal demographiccharacteristics. The first of these, mortality rate, is an expression of thenumber of deaths from a particular cause that occur per unit of population andtime, a frequent unit of population in military practice being 1,000 men and theinterval of time 1 year. Mortality rates in this discussion are usually on themore practical basis of 100,000 average strength per year. The rates for shorterperiods are based on the assumption that the observed frequency would have,continued over a year. The mortality rate represents a definite and certainmilitary loss, irrespective of cause, of time, or of nature, and is one of theabsolute indexes of the cost of war.
The morbidity rate, when expressed as an admissionrate, refers to the number of persons affected by a given condition asdetermined by patients admitted to hospital or quarters and regularly iscomputed in terms of 1,000 per annum per average strength. Morbidity rates as sodefined represent not all persons affected but only (1) those persons admittedto hospital or quarters (those seriously enough involved to be absent fromduty), and (2), for most diseases, certain patients who are treated while theyremain in a duty status and whose cases are carded for record only.Nevertheless, these indexes of illness as employed in military practice are moresatisfactorily indicative of the existing situation than is usual in publichealth or preventive medicine, because reporting is particularly good. Thesignificance of any particular morbidity rate as an influence on tactical andstrategical operations depends, in the first
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instance, on the duration of the disability ordinarily associated with thecondition; secondly, on the expected fatality; and, finally, on the prospect forcomplete recovery and return to duty.
The daily noneffective rate represents the number ofmen absent from duty by reason of disease or injury for each 1,000 troopstrength per day. The complementary value shows the proportion availablefor duty at any prescribed time. Persons suffering permanent disability eitherpartial or complete as a result of a disease or injury of sufficient seriousnessto interfere with ordinary duties are discharged from military service. Thedesignation 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 succeedingvolumes are preliminary data based on sample tabulations of individual medicalrecords. They include both primary and secondary diagnoses. As such, they aredesignated incidence. Admission rates refer only to primary diagnoses. Morbiditythus may be expressed in either term. Incidence is usual. The final tabulationswill introduce some changes but presumably not enough to affect theinterpretations made. In some instances, information is from weekly summaryreports, field records which lack the reliability of analysis from individualmedical records.
Data on deaths are on the same basis as data forcases, except that total deaths of the war (table 1) are from The AdjutantGeneral`s final report. Examination of individual case records will resultin some rearrangement of the data of table 1 but not in number of deaths.
TABLE 1.-Admissionsand deaths, by classification, U. S. Army,1942-45
The communicable diseases are listed within a number ofcategories in the official tabulations. The most significant medically and froma military standpoint are the infectious and parasitic diseases, which representthose communi-
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cable processes of specifically determined etiology; they have an estimatedincidence of 126.4 cases per annum per 1,000 average strength. The list isessentially that of the Office of Vital Statistics, United States Public;Health. Service, except that influenza, bacterial pneumonia, and rheumatic feverare included. The largest block of communicable disease is the commonrespiratory diseases with an annual rate for the total Army of 159.3 per 1,000.The diarrheas, excluding the dysenteries, are another appreciable source ofmorbidity; incidence 29.1 per 1,000 per year. Pneumonias other than specificbacterial, incidence 10.1, and fever of undertermined origin, incidence 5.7, areto be added. Miscellaneous items of lesser number, corresponding to those listedin Control of Communicable Disease in Man (American Public; Health Association,1955) and not included among the categories given above contribute a furtherincidence of 12.7 per annum per 1,000; the main items are dermatophytosis,impetigo contagiosum, and trachoma. The greater proportion of the conditionslisted are infectious and reasonably to be added to the specific infectious andparasitic diseases in accumulating a total of communicable disease. Rates ofincidence as here cited are in part estimates, particularly for cases reportedas secondary diagnoses during 1942 and 1943. The incidence for all communicabledisease on this basis is 343.3 per annum per 1,000.
The information on admissions (primary diagnoses) isalmost complete. The rate for disease for the total Army during 1942-45 was587.5 per annum per 1,000 average strength. Similar data for the communicablediseases as just presented give an admission rate of 310.4. Thus, in thetotal Army during the war, more than one-half of all reported disease was of acommunicable nature.
The aim now is to determine the place of communicable diseaseamong military casualties, and the influence of these diseases on militaryoperations, in this war and in relation to other wars and other years. Thepractical approach initially is through disease of all forms principally,because the communicable diseases were more than one-half of total disease inWorld War II, because the exact numbers of infections remain indeterminate byreason of indefinite clinical identification within several large groups, andbecause in records of earlier years the separation of communicable from otherdisease processes was still looser.
DISEASE AS A FACTOR IN MILITARY OPERATIONS
The ratio of deaths from disease to deaths from battlecasualties for the wars of the 18th and 19th centuries was sometimes as great as12 to1. A generally accepted ratio was 4 to 1; as for example, in theRusso-Turkish War of 1877-78 where deaths from disease numbered approximately80,000 and those from battle casualties 20,000. The ratio during the campaign inthe Crimea was even greater, with some 70,000 deaths from disease and 7,500 from battlecasualties among the French forces. Approximately three-fifths of thedisease
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and battle deaths that occurred in the Union Army during the American CivilWar were deaths from disease, which marked an improvement over the Mexican Warwhen deaths from disease outnumbered those from battle casualties in theproportion 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 ofabout 5 to 1.
Fewer deaths from disease than from battle casualtieswere noted for the first time in the War of 1864 whichDenmark waged against Austria and Prussia (table 2). Both opponents established a ratio of 1 death from disease to2 for casualties of battle. Although the number of men engaged in that war wassmall, communications between the armies and home countries were good andenvironmental conditions were favorable. The War of 1864 was nevertheless aremarkable event-a turning point in the history of wars. In theFrancoPrussian War of 1870-71, the first major war to see the new ratiomaintained, the German Army had a proportion of 0.86 deaths from disease foreach battle casualty. The health record of the German Army has beenconsistently good, for of five wars, dating from the Danish action of 1864 andincluding World War I, deaths from disease have been less than those from battlecasualties with the single exception of the War of 1866 and that was close toparity. The Russo-Japanese War of 1904, the next great conflict after theFranco-Prussian War, gave the Japanese forces an opportunity to set a new ratioof 0.37 deaths from disease per battle casualty.
World War I was the first United States experience in whichdeaths from disease were fewer than deaths from battle casualties, and then thiswas 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, therate was still slightly greater for disease. World War II brought a completedeparture from previous experience and a health record never approachedpreviously in any war. The ratio of deaths from disease to those from battycasualties was 0.07: 1.
The gains which have been made in recent times areprimarily due to improved control of acute infectious disease. Not only aredeaths from this cause far less frequent in proportion to those at risk, but thecase incidence of communicable disease is decidedly less. This has broughtsignificant changes in the qualitative character of the losses that still resultfrom disease as distinguished from injury and battle casualties. Noncommunicabledisease 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 wasstrongly reversed in World War II. Even nonbattle injuries became a moreimportant source of fatal casualties. Deaths, however, are not the solemeasure of costs of disease and injury, nor are they
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always the most indicative. The intent now is to examine disease in World WarII in relation to the two classes of injuries, battle and nonbattle, and then torelate the specific infectious and parasitic diseases to disease as a whole.
Mortality From Disease
Disease in World War II ranked third among major classesof deaths (table 1). The contrast with other wars is extreme, where deaths fromdiseases outnumbered the total of all others and sometimes in a proportioninversely as great as that presented here. On the basis of deaths, diseaseclearly has decreased significantly as a factor in military operations.
Disease Morbidity
As a cause of disability in World War II, disease rankedfirst among the three major categories of military casualties (table
1); in fact, the number of admissions for disease was more than five timesas great as the number of admissions for battle casualties and nonbattleinjuries. Somewhat more than 85 percent of all admissions to hospital andquarters were because of conditions
CHART1.-Admissionsto hospitals and quarters for diseases, nonbattle injuries, and battlecasualties, 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 largestand since environmental conditions there were those of a temperate region.
For each of the 4 years that the European theater wasin existence, disease was the most frequent cause of admission to hospital orquarters (chart 1). The highest admission rate was in 1943, the widespreadepidemic of influenza in the autumn of that year being a contributing factor.The rates from year to year showed little variation, irrespective of whether thebattle was fast or slow. There was no direct correlation between the activity ofmilitary operations and the frequency of disease. The numbers of personsaffected were regularly great, since each year about one out of every-twosoldiers tended to suffer some disability from disease of sufficient degree tointerfere with military duties. The regularly occurring annual peak of incidencein late autumn or early winter (chart 2) shows common respiratory infection tobe the dominant factor in frequency of disability due to disease.
CHART 2.-Admissionsto hospitals and quarters for all diseases, ETOUSA, bymonth, 1942-1945 1
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No particular significance attaches to the experience ofthe first 2 years in the European theater. The morbidity rates for disease werein all respects satisfactory and the health record good. The striking feature isin respect to the last 2 years. During the height of the campaign in continentalEurope which started in the middle of 1944 and ended in late spring of 1945, themorbidity rates for disease as judged by admission to hospital and quarters wereat a lower level (chart 2) than at any other time during the war. Proverbiallyand throughout the history of wars, this is the time when losses have beengreat. Granted that many soldiers will not report sick during the height ofmilitary operations, and particularly in time of advance, nevertheless, the factthat so few were disabled by disease is perhaps the clearest evidence of theprogress made in environmental sanitation and in the practice of preventivemeasures.
Noneffective Rates for Disease
The proportion of a command absent from duty on a particularday is a reflection of current morbidity and of the deaths that occur. Theextent of noneffectiveness is also an index of the kinds of disability, forthose of disease in the age groups that characterize an army are commonly shortwhile 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 andover the war period, the preliminary estimates per day per 1,000 averagestrength are 6.38 for nonbattle injury, 7.73 for battle casualty, and 30.22 fordisease.
The significance of the noneffective rate and the drain onoperating efficiency of an army is expressed in simpler terms by considerationof the number of man-days lost. Estimates in round numbers show a total of 72million days lost because of battle casualties for all the Army troops,including the Air Force, during World War II. This exceeds the correspondingfigure of 59,863,000 for nonbattle injuries, but scarcely approaches the loss of285,918,000 days attributed to disease (table 3). A comparable estimate for dayslost because of infectious and parasitic disease is 55,688,000 days of the total285,918,000. The experience of ETOUSA again is drawn upon to indicate
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CHART3.-Average daily noneffective rates, ETOUSA, by months, February 1942 to June1945, inclusive
variations in noneffectiveness over time (chart 3). The data are from fieldrecords but are sufficiently- reliable to establish relationships and trends.
Discounting the early part of 1942 when the small troopstrength of the European theater accounted for irregularities in thedemonstrated 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 andminimal values during the summer. The seasonal incidence of upper respiratoryinfections was the main influence on this fluctuation. Variations from year toyear were not great until the latter part of 1944 when the values for all monthsincreased precipitately over the established norm. This was coincident with thebeginning of active operations in Continental Europe.
The division of this particular combat experience intothe three components which make up the total noneffective rate (chart 4) givesready demonstration of the factors involved. The noneffectiveness related todisease continued according to established pattern, with rates in 1945 almostidentical with those that characterized 1944, the year just preceding thecampaign. A significant part of the excess noneffectiveness came about through agreater frequency of nonbattle injuries, principally cold injury. The mostimportant variable was that of battle casualties, with the data of chart 4demonstrating clearly the high noneffectiveness of the campaign period as due tothat cause.
The generalizations to be drawn from this experience are thatyear in and year out the principal cause of noneffectiveness of troops isdisease. The losses from nonbattle injuries are ordinarily much less, aboutone-fifth of those from
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disease. The noneffectiveness that comes from battle casualties is subject togreat variation wholly related to the nature of operations. The impression isnot to be left that the cost of battle casualties is unpredictable, for theexpected losses in a major operation can be estimated with an exactness rivalingthose of disease and injury.
All three classes of casualties give rise to irregularfluctuations in morbidity and in noneffectiveness which can be related with muchcertainty to environmental, seasonal, or other ecologic factors. The peaks ofexcess incidence that mark the behavior of battle casualties and nonbattleinjuries may be as outstanding as any introduced into the general curve throughaction of an epidemic of disease.
Discharge for Permanent Disability
The final consideration of noneffectiveness is that ofseparation from the military service by reason of physical or other disability,variously due to residual effect of battle casualty, nonbattle injury, ordisease. Such losses in World War II greatly exceeded the losses from death;death accounted for 312,293 absolute losses, separation because of significantlyimpaired usefulness the much greater number of 956,232. The distributionaccording 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 wasalmost 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 toidentify the contribution of the communicable diseases to these several ratesand indexes. The main reliance is on those conditions collectively grouped asthe infectious and parasitic diseases, a category used in common in bothmilitary and civilian vital statistics although with minor variation in thediseases included. The group is not synonymous with the communicable diseases.Many diarrheas are surely dysentery, to such an extent that the two conditionsare considered jointly in a subsequent chapter. They cannot be adequatelyseparated. An interpretation based solely on confirmed bacillary dysentery, evenwith clinically recognized dysentery added, is not representative. The commonrespiratory diseases presumably include a goodly proportion of the influenzas;this group is excluded and so is a part of the pneumonias. Large numbers offever of undetermined origin in malarial zones are actually malaria. Theinfectious and parasitic diseases (as listed in table 10, p. 26) are however themain problem and in large measure determine the military significance of thecommunicable diseases.
THE SPECIFIC INFECTIOUS AND PARASITIC DISEASES
The long-term behavior of the infectious and parasiticdiseases in respect to the general population of the United States is to beascertained through comparison of deaths from these diseases with deaths fromall causes; it is a
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useful control in judgment of the military experience. Deaths are thenecessary criteria because reporting of cases in the general population isincomplete for all of the communicable diseases, and a number are not reportedat all. Selected years indicate a consistent and impressive downward trend(table 5). Infectious and parasitic diseases, as listed by the Bureau ofthe Census in Vital Statistics of theUnited States, do not include pneumonia and influenza, whereas United States Army tabulationsfor World War II include bacterial pneumonia and influenza.
Death rates for infectious and parasiticdiseases show a material variation (table 6). Rates increase progressively withage, tuberculosis being a major influence. The proportion of deaths frominfectious and parasitic diseases to deaths from all causes is materiallygreater at the younger ages. One reason for the emphasis on communicablediseases in military practice is thus evident. Military populations have astrong bias in ages in which the infectious and parasitic diseases account forthe largest proportion of deaths and also a bias in males, among whom deathrates exceed those for females.
The greater problem presented by the infectious and parasiticdiseases in the general as contrasted with the military population of the UnitedStates is illustrated in chart 5 where the rates for the two populations arecompared by 5-year periods from 1900 to 1950. The list of infectious andparasitic diseases is again that of the Office of Vital Statistics, pneumoniaand influenza being deleted from the Army data. The frequency is regularlyless 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 generalpopulation; the advantage still holds.
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TABLE 6.-Average annual deaths, all causes,and deaths from, infectious and parasiticdiseases, total United States, byage groups, 1948-52
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Army Experience Over the Years
The extent of the problem provided by the infectious andparasitic diseases is measurable for the Army in terms of both morbidity andmortality, something which is not possible for the civilian population.Admissions to hospital and quarters represent, within limits of humanfallibility, all illnesses due to specific infections where specific infectionwas the primary diagnosis. Because of coding practices which prevailed from 1924through 1943, data for that period as well as for the war years 1942-45 may beconsidered for all practical purposes as representing incidence; namely, bothprimary and secondary diagnoses. Data from 1946 are admissions, primarydiagnosis, only. The series of data in chart 6 includes the last five wars ofthis country. They mark the coming and going of epidemics and the interveningendemic periods but, withal, the continuing downward trend in morbidity andmortality. The high point in cases and deaths is that of the Spanish-American War, 1898, with anadmission rate somewhat less than 1,000 per annum per 1,000 average strength anda death rate of 21 per 1,000. The influenza epidemic of
CHART 6.-Admission1and 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. Mobilizationyears of 1917 and 1940 produced higher rates as recruits were brought togetherin large numbers. The fluctuations from year to year were sometimes great, butthe outstanding observation is that deaths from this group of diseases showedalmost no departure during World War II from the established trend; this wasdespite potential hazards never before faced by our military forces.
Previous Wars
The changing behavior of the communicable diseases isstrikingly brought out by comparison of morbidity and mortality rates forinfectious and parasitic diseases in the several wars of United States historyfor which records are reasonably reliable (table 7). Deaths per 1,000average strength have dropped
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 of112.46 in World War II is wholly satisfactory in relation to the admission rateof 1,030.34 of the Civil War. Each successive war showed definite andprogressive improvement over its predecessor; the proportionate gain in WorldWar II over World War I far outdistanced all others.
World War II
About 20 percent of all reported disease in the Army forthe war years of 1942-45 was in that group classed as infectious and parasiticdiseases, excluding rheumatic fever, the number of cases being nearly 3,200,000to give an incidence
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rate of 124 per annum per 1,000 average strength (table 8). Numbers ofcases were about equal for troops stationed in the United States and overseas, but the rates were materially greater for overseas troops. Troopsstationed in continental United States had a rate of 107; the rate for those serving abroad was 148. The proportion ofinfectious and parasitic diseases to all disease was of similar order, for 18percent of reported cases at home were of this nature; the frequency for troopsserving in theaters of operations was 26 percent.
TABLE 8.-Admissionsfor all disease and incidence of infectious and parasitic diseasesin the U.S.Army, by theater or area of admission,1942-45 1
Parallel relationships held for deaths from specificcommunicable disease (table 9). The proportion of deaths from infections todeaths 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 percentfor cases. For troops stationed in the United States, some 20 percent of all deaths from disease were due to infections; theproportion overseas was just about three-fifths greater, or 32 percent. Thespread between absolute death rates from infectious disease at home and abroadwas also strikingly different-11 per annum
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per 100,000 average strength in theUnited States and 20 overseas. Stated in other fashion, the risk of contracting an infectiousdisease during service overseas was greater than at home and the risk of deathfrom such disease was still greater.
A possible explanation of this situation is that thecommunicable diseases of overseas areas included infectious processescharacterized by higher fatality than existed in the United States. There is the second possibility that the kinds of infectious disease were muchthe same but with enhanced fatality related to environmental differences. Athird consideration is that the decisive factor may be the stress and strain ofcombat, a mode of life in the field contrasted with that in training and inbarracks and with attendant difficulties in providing an equal quality ofmedical care. The same considerations enter into explanation of the attack ratesabroad, which are appreciably greater than under home conditions but less sothan the observed differences in death rates.
The contribution of the infectious andparasitic diseases to the total amount of disease resulting in separation fromthe service because of disability was insignificant. Among enlisted men only 2.6percent of total separations
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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 andparasitic disease is, however, impressive; in all, 25,115 among enlistedpersonnel.
The distributions of infectious disease bytheaters of operations, by the several years of military operations, and by thekinds of communicable disease that characterized each may now be examined toadvantage. To do this, it is necessary to know the size and nature of theproblem in its entirety; that is, to know the kinds of infectious and parasiticdisease, 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 variedgreatly from one theater to another, from a low rate of 53 per annum per 1,000average strength in the North American area (table 8) to a high of 247 in theChina-Burma-India theater. Other theaters and areas with high incidence were theMiddle East (rate 228), Mediterranean (rate 222), and the Southwest Pacific (rate 194). A scant familiarity withthese regions is enough to bring out the low levels of environmental sanitation,the greater frequency of infection among peoples resident there, and the commonpresence of some kinds of communicable disease scarcely known in temperateregions of the Western World.
High rates for communicable disease among foreigntroops operating in such regions would be anticipated, because of the strangeenvironment and because of a susceptibility presumably greater than that ofpersons indigenous to the region. It is a matter of satisfaction, however, thatwhen environmental conditions were similar and risks comparable, the morbidityrates for communicable disease in soldiers overseas compared favorably withthose 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 theZone of Interior and the selection and greater resistance of seasoned troopssent overseas.
Morbidity rates for infectious and parasitic diseases in theNorth American area (53 per annum per 1,000 average strength) were not only thebest of any area or theater of operations but they were about one-half those fortroops of continental United States. A portion of the territory of this theater was American, with the advantagesof close cooperation with civilian health authorities and an organization forhealth which followed the United States pattern. Troops were isolated from contact with civilian populations more thanin many situations, either at home or abroad. Troop strength was small andrelatively stable, lacking the continual buildup which characterized so manyoperational areas. These factors presumably restricted the continuous
seeding of a command with newly introduced infection. On the other hand,troops
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of this region of ten were subjected to rigorous cold and a primitiveenvironment which found expression in unusually high rates for nonbattle injury,a type of disability which then and now is a feature of cold climates. Thisenvironment might well have been expected to favor occurrence of communicablediseases. The observed rates are wholly commendable.
The European theater, the largest in respect to troopstrength and the site of some of the most active combat of the war, hadincidence rates for infectious and parasitic diseases which averaged 106 perannum per 1,000 average strength for the 4 war years, a rate about equal to thatfor continental United States, which was 107. Climate and environmentalconditions 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 withan old and well-established health organization.
Two conclusions may be drawn. First, armed warfare does notof itself bring increased hazard of the communicable diseases to troops in areasof active combat. The European theater had rates about equal to those ofcontinental United States which was a training area with no open warfare. Within the European theateritself, communicable disease was of more concern in service troops of theCommunications Zone than in combat units in forward areas. Second, excessincidence of infectious disease seems in this experience clearly related toenvironments conducive to greater risk and to military operations in areas ofknown high prevalence of these diseases. Another reason for emphasis oncommunicable disease in military practice thus becomes evident the need inglobal warfare to operate in regions where the communicable diseases are themain factor in morbidity and where rates for infectious and parasitic diseasesin American troops may be expected to be greater than those prevailing in thehome country.
Deaths by areas and theaters of operations
With minor exceptions, death rates from infectious andparasitic diseases arrange themselves in much the same order for the severaltheaters 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 amortality rate of 53 per annum per 100,000 average strength and the NorthAmerican area with the lowest incidence had the lowest death rate, 10 per100,000. Material differences in rates between theaters are evident.
Death rates from communicable disease in the theatershave a greater spread over death rates of Zone of Interior troops than do ratesof incidence in these two elements of command. For example, morbidity rates forthese diseases as a whole in the China-Burma-India theater were a trifle morethan twice those for continental United States; mortality rates were five times as great. The North American area had lessthan half the continental United States morbidity rate, but death rates were about equal in the two areas.
26
27
28
29
30
The European theater had approximately the same incidencerate as continentalUnited States but had a mortality rate of 12 per annum per 100,000 average strength comparedwith 11 for the continental United States. Broadly viewed, the morbidity rate for infectious and parasitic disease amongall troops overseas compared with those at home was greater by about 39 percent.Death rates for these diseases overseas were essentially 100 percent more thanin the Zone of Interior.
Possible explanations are that the kinds of infectiousdisease active in the two situations are different, that diseases present incommon occur with greater severity, or that differences in quality andfacilities for medical care are a determining factor. The validity of the firsttwo assumptions may be determined from examination of the detailed frequenciesof cases and deaths by individual diseases as presented in table 10. The thirdpossibility is difficult to evaluate, involving as it does the balance betweenpreventive and curative services and the lack of factual data capable ofquantitative analysis. One conclusion is definite: death rates for infectiousand parasitic disease in overseas troops are in this experience proportionatelygreater in relation to incidence than for Zone of Interior troops, acircumstance which holds whether absolute incidence in the particular theater ishigh or low.
This analysis of cases and deaths from infectious andparasitic disease in the war years of 1942-45 is now extended from differencesaccording to place (overseas theaters of operations in comparison with the Zoneof Interior) to a consideration of time relationships. The suggestion has beenraised that the significance accorded to communicable disease in militarypractice may rest in more frequent occurrence of epidemics of the usualfluctuating endemic diseases or in outbreaks or threatened outbreaks of thegreat pandemic diseases which include the designated internationallyquarantinable diseases and influenza. If that be so, then irregularities incases and deaths should be evident in random fashion from one year to another,affecting parts of the total command, and identifying local epidemics; or auniform irregularity marking a single year, affecting all theaters, andestablishing the presence of a pandemic of the nature of the influenza outbreakof the First World War.
Communicable diseases by years, 1942-45
An outstanding feature of the incidence of infectious andparasitic disease among troops of continentalUnited 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 per1,000 average strength.
No serious deviation in the proportion of cases ofinfectious and parasitic disease to all disease occurred during the 4-yearperiod, either in the Zone of Interior or overseas; the ratio in both instanceswas greatest in 1945. Since the two major fractions of the command behaved insimilar fashion, it follows that the same pattern held for the total Army.
Rates of incidence for overseas troops were on an averagesome 39 percent higher than for troops in the Zone of Interior, but the trend inbehavior over
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the 4 years was much the same for both. The second year of the war, 1943, hadincreased rates over the first year, appreciably so for troops overseas; themost favorable rates were in 1944, and incidence returned to the higher levelsof 1942 and 1943 in the last year of combat.
Death rates for the infectious and parasitic diseases duringthe 4 years and for the Army as a whole followed the same pattern as the ratesfor cases except that the rise in 1945 was lacking for ZI troops, the shiftingof units and rapid demobilization having an effect on troop strength andtherefore on rates.
The ratio of deaths from infectious disease to deaths fromall disease for the Army as a whole was fairly fixed throughout the war; themoderate increase in 1945 was related to troops overseas.
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These four sets of data, the ratio of cases and of deathsfrom infectious disease to all disease and the annual rates for cases and deathsdue to infectious processes, suggest the general behavior of communicabledisease during the war to have been characterized in the first 2 years by asomewhat enhanced endemic level of infection, punctuated by local epidemics.This circumstance is usual for recruits brought together in large numbers as inthe continentalUnited States. Rubella and meningococcal meningitis in 1943 were good examples of the kindsof epidemics that occurred.
Troops arriving overseas had, in some instances, theadvantage of fairly prolonged seasoning, but often they did not. Irrespective ofseasoning, in foreign theaters they commonly faced infections with which theyhad had no previous experience, such as filariasis in the South Pacific andscrub typhus in the Southwest Pacific Area. Amebiasis, ordinarily an endemicdisease, reached epidemic proportions in the China-Burma-India theater andseveral others. Both continental and overseas troops thus encountered anunfamiliar mode of life, a strange environment, and, for overseas troops, a lifein places where risk of contact with infection was notably greater than any towhich they had been accustomed.
The rates for infectious and parasitic disease thatprevailed in the third year of the war seemingly represent expectancy in termsof a trained functioning army. Case rates and death rates were improved both inthe Zone of Interior and overseas.
Both incidence and mortality were greater in 1945 for theArmy as a whole. The incidence rate for home troops was in general comparable tothat 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 tothe new conditions of a theater. The excess was largely related to the periodwhen the war ended and thereafter.Until the war ended, the record for 1945 wasmuch the same as for 1944. In the postwar period, military discipline relaxed,and control measures were more difficult to apply; for some diseases, especiallythe venereal diseases, rates increased precipitately. Recovered prisoners of waralso made their contribution to greater incidence and mortality, particularly inrespect to tuberculosis.
Two medical events were of general occurrence,affecting troops in appreciable numbers both in the Zone of Interior andoverseas. The first, in 1942, was the manmade epidemic of serum hepatitis; thesecond, in 1943, was an outbreak of influenza A. The data discount theoutstanding prevalence of any one of the great epidemic diseases, the famous sixquarantinable diseases.
Interest now turns to the kinds of communicable diseaseinvolved in the troubles of recruits in the Zone of Interior and of newcomers toan overseas theater of operations, to identify such local epidemics as occurredunder both sets of circumstances, to compare the endemic disease thatcharacterized the various theaters of operations, and especially to view thebehavior of what history has long established as the infectious diseasespeculiar to military operations.
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ContinentalUnited States
The problems of specific communicable disease incontinentalUnited States centered mainly in the first 2 years of the war in which rapid buildup of theArmy was taking place. They were the problems of recruits.
Tuberculosisof all forms was consistently at a low level, 1.48 cases per annum per 1,000average strength. for the 4 years, largely because of the effective screening atthe time of induction. The first and final years had a higher incidence than theintervening years, 1.86 and 2.16 per 1,000, respectively. The death rates fortuberculosis decreased from 3.46 per 100,000 average strength in 1942 to 2.15 in1945, the average for the 4 years being 2.64.
As in theaters of operations, the venereal diseases in theZone of Interior contributed strongly to the incidence rate of the infectiousand parasitic diseases. Indeed, for the war years as a whole, gonorrhea headedthe list for reported cases of infectious and parasitic disease both in thecontinentalUnited States and overseas. The 1942 rate for gonococcal infection in troops of continentalUnited States was 31.44. In 1945, this rate rose to 43.21, a circumstance which held for anumber of the communicable diseases as discipline relaxed with the end of thewar and an association with civilian populations was greater and easier.Syphilis, excluding neurosyphilis, started with a satisfactory rate of 6.88 in1942, reached a high point of 19.60 in 1944, and declined thereafter. The incidence of chancroid in Zoneof Interior troops was one-fifth that of troops stationed overseas. Rates forgonorrhea also favored troops at home, 31.52 compared with 38.81 per 1,000 foroverseas troops as a whole and for the war period. Overseas troops had much thebetter rates during the first 3 years, but, with cessation of active combat,that advantage was lost in 1945 when gonococcal infection increased to suchextent that the year ended with an annual overseas incidence of 55.72. For thewar period as a whole, syphilis was far more frequent among Zone of Interiortroops than those overseas, the respective rates, excluding neurosyphilis, being15.12 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 mostforeign areas where American troops were stationed. Incidence was somewhathigher, 16.20, in 1942, but the bulk of cases occurred in 1943 during anepidemic of type A. Death rates were low, 0.30 and 0.15 per 100,000, for the 2years. Cases and deaths from bacterial pneumonia were in the same pattern, withthe highest admission rate (3.52 per annum per 1,000 average strength) in 1942.
Meningococcal meningitis was second among causes of deathfrom infectious and parasitic disease with rates of 2.41 per 100,000 strengthper year in 1942 and 4.48 in 1943, the 4-year average being 2.58. Meningitisthus holds its place among communicable diseases of military significance, butthe epidemic of 1943 (incidence rate 1.23 per 1,000) was a minor event comparedwith the outbreaks of World War I.
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The common communicable diseases of childhood consistentlygive concern in recruit populations. All were relatively frequent in the first 2years, with the exception of whooping cough which seems never to give muchtrouble 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 WarII experience of troops in the United States, mumps behaved satisfactorily,incidence 5.59 per annum per 1,000 average strength; measles was of lesserconsequence, 3.69 per 1,000; while rubella in this instance produced theepidemic with 125,530 cases and an incidence of 8.51 per 1,000. Most cases ofrubella (88,775) occurred in 1943 to give an attack rate of 17.13 per 1,000average strength. Chickenpox as usual was inconsequential, incidence 0.58 casesper 1,000 strength. The frequency of both chickenpox and mumps remained much thesame over the 4 years.
Epidemic hepatitis and coccidioidomycosis providedproblems of special note among infectious and parasitic diseases of continentalUnited States troops. Hepatitis was largely limited to 1942, with 33,569 admissions, a rateof 12.63 per 1,000; this was primarily serum hepatitis, easily the largestepidemic of this particular form ever recorded. A full account is given inanother volume. 1
Thereafter, infectious hepatitis, a disease justifiablyincluded among infections of military importance, was the prevailing form. Therates for infectious hepatitis were low in 1943 and 1944, but the last year ofthe war gave an annual admission rate of 2.08 per 1,000 average strength. In thecontinentalUnited States, the rate never reached the proportions that it did in a number of overseastheaters, especially in the last 2 years of hostilities. Serum hepatitisoccurred among overseas troops in 1942, but thereafter it was the directlycommunicable infectious hepatitis that was responsible for the continued highadmission rates among troops overseas-14.79 in 1943, 6.44 in 1944, and 15.16 in1945.
Coccidioidomycosis, by contrast, was mainly a diseaseof troops in theUnited States. Of 3,809 cases for the Army as a whole, 3,626 were in continentalUnited States. For the 4-year period (1942-45), the greatest number of cases, approximately1,310, occurred during 1943. Deaths totaled 32 in theUnited States and 7 overseas. The death rate was not great (0.22 per annum per 100,000average strength in the continentalUnited States), but the behavior of the disease and the problems presented were anoutstanding event of World War II medicomilitary history (p. 286).
Among continental United States troops, the chief causes ofdeath due to infectious and parasitic diseases were tuberculosis, 2.64 deathsper annum per 100,000 average strength; meningococcal meningitis, 2.58;bacterial pneumonia, 1.69; poliomyelitis, 0.58; and infectious hepatitis, allforms, 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 DiseasesTransmitted Through Contact or Unknown Portals of Entry. [Inpreparation.]
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European Theater of Operations
In the European theater, the incidence of infectious andparasitic diseases, next to the lowest among theaters of operation and about thesame as that of continental United States troops, suggests little of particularnote in a command that at one time involved more than 3,000,000 men and standsas the largest foreign effort of the United States Army in this or any otherwar.
The influenza epidemic of the early years of World WarII was more or less worldwide. Incidence was greater among troops of theEuropean theater, 20 and 18 per 1,000 for the years 1942 and 1943, than fortroops at home and indeed was exceeded only by the experience of theMediterranean theater, 39 and 15 per 1,000 during the same 2 years. The Easternor 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 favoredtroops overseas; Zone of Interior troops lead incidence rates of 16 in 1942 and13 in 1943; for all troops overseas, incidence was 12 and 12 per 1,000 in thecorresponding years.
Rates for bacterial pneumonia were in those years appreciablyhigher in continentalUnited States than in overseas areas, even in the European and Mediterranean theaters where influenza was more common. This contrast invites considerationas to the contribution of exposure, which is presumably greater in fieldoperations than in training areas.
The venereal diseases lead an erratic history in theEuropean theater. Incidence during the years of active combat was lower thanamong 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 itincreased to 71.71. Chancroid rose from a frequency of less than 2 per 1,000 to5.72. Syphilis, excluding neurosyphilis, essentially doubled in frequency overthe previous year, showing an incidence of 12.15 per 1,000. Comparing overseastroops as a whole with those of the Zone of Interior, gonorrhea was more of aproblem overseas (38.81 per 1,000) than at home (31.52) ; chancroid wasoverwhelmingly a disease of soldiers stationed abroad, 7.29 against 1.43 per1,000; while syphilis, excluding neurosyphilis, was more frequently observedamong domestic troops, 15.12 per 1,000 average strength for troops at home and8.89 for those abroad.
Viral hepatitis was a problem in the European theater. Thoughserum hepatitis occurred rather extensively in 1942, the greatest problem waswith infectious hepatitis which occurred mainly in troops operating incontinental Europe, in 1944 and 1945. The number of admissions in 1944 was 4,330 (rate 2.58 per1,000), and 20,575 admissions in 1945, a frequency of 8.67 per 1,000 averagestrength. For the 2-year period, 1944-45, combined deaths from serum andinfectious hepatitis had ranked fifth among deaths from communicable disease inthe theater, an average rate of 1.14 per annum per 100,000 average strength.
Data for scarlet fever and the partial information nowavailable for streptococcal sore throat indicate that hemolytic streptococcalinfections were
36
less prevalent among troops of the European theater than in continentalUnited States, both regions being in the north Temperate Zone.
Themalaria incidence rate reported in the theater, 4.88 per 1,000 for the 4-yearperiod, was almost wholly relapse of original infections contracted in othertheaters 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 recognizedin the European theater were only a fraction of those reported for troops in thecontinentalUnited States. Mumps was the commonest, as it usually is among seasoned troops. The report ofmore herpes zoster (1,295 admissions) than chickenpox (774 cases) is unusual.
Thatconcern about communicable disease increases as a war ends is a principle ofmilitary preventive medicine. The venereal diseases illustrate this well, as dothree other infectious diseases of this experience, typhoid fever, paratyphoidfever, and diphtheria. Both typhoid fever and paratyphoid fever were almostnonexistent in the early years of the theater-4 cases of each disease occurredover a 2-year period. In 1944, 25 cases of typhoid and 20 of paratyphoidoccurred during active combat and field operations. The main trouble, however,centered about those spring months of 1945 which saw the end of hostilities. Forthe year as a whole, the number of cases of typhoid and paratyphoid totaled 35and 60, respectively. The really serious problem, however, was among theprisoners of war (p.182).
Diphtheria in the European theater had much the samehistory. 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 wasconsoli dated inWest Germany where the disease was highly prevalent in the civilian population. Admissionsfor the first 6 months of the year were at the rate of 0.60 per annum per 1,000average strength; the rates were twice that during the last 6 months, 1.26 per1,000.
The10 cases of louseborne typhus fever in 1945 warrant little attention ofthemselves in the total account of communicable disease. The significance liesin that small number of infections among troops operating in a region wheretyphus fever was widely dispersed and broadly epidemic. Military preventivemedicine has no finer accomplishment.
The principal cause of death from communicable disease in thetheater was tuberculosis with a death rate of 4.41 per 100,000, in large partdetermined by the 6.02 rate of 1945, this in turn related chiefly to recoveredprisoners of war. The death rate for tuberculosis was greater in the Europeantheater than in others. For all troops overseas, deaths from tuberculosis weresome 47 percent in excess of those for men stationed in continentalUnited States.
Mediterranean Theater of Operations
The environment in which troops of this command were calledupon to operate was one of the more difficult among American areas of influence;the
37
communicable diseases consequently occurred frequently. Incidence and deathrates for tuberculosis were less than the average for all overseas troops; forpneumonia, they were somewhat greater. For malaria, the incidence rate was 42.68per annum per 1,000 average strength, placing the theater fifth among the eightoverseas 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. Duringthe 4 years of war, there were 63,292 cases of malaria in the theater.
Next to the Southwest Pacific areas, epidemichepatitis was most prevalent in the Mediterranean theater. Data on admissionsare available only for the last 2 years of the war: 18.16 per 1,000 averagestrength in 1944 and 19.88 for 1945. The death rate per 100,000 for the 2 yearswas 3.39 per annum, about one-half that for the combined Pacific theaters; in1945 in the Southwest Pacific Area, admission rates reached 34.85 per annum per1,000 average strength.
The venereal diseases were of more frequent occurrence in thistheater 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 therate for the European theater, which was 50.09. As in other theaters, rates roseat the end of the war; the main difference was that in the Mediterranean theaterthe rise started a year earlier. For chancroid, the 22.25 per 1,000 annual rateover the 4 years exceeded that for any other major command, as did the syphilisrate of 15.22, even though the latter rate was only fractionally greater than incontinentalUnited States.
The dysenteries were an outstanding problem. The ratefor bacillary and unclassified dysentery combined was 6.43 cases per annum per1,000 average strength; for amebiasis, the rate was 1.26. These three categoriesare only part of a larger group of acute intestinal infections described indetail in a subsequent chapter (p. 340).
The Mediterranean theater had a moderate poliomyelitisproblem. Other theaters had somewhat greater incidence, notably theChina-Burma-India theater with 0.18 per 1,000, compared with 0.09 for theMediterranean area, and death rates were higher, China-Burma-India being 8.2 perannum per 100,000.In all, this theater had 127 cases of poliomyelitis during the4 years.
Fungus infections and the intestinal parasites, while of someconsequence, were measurably less significant than in the Pacific andChina-Burma-India theaters. Sandfly fever was a special problem. Incidence rateswere 7.56 per 1,000 strength witti a total of 11,206 cases, distributed withcomparative regularity over the years of 1943-45.The theater was activated inlate 1942, and only 11 cases occurred that year. There were no deaths in thetotal series of cases. The number of cases in the Mediterranean theater exceededthat in any other, but rates of incidence were only one-fourth those prevailingin the Middle East theater, a smaller command which had 4,399 cases.
The newer methods for control of louseborne typhus fever hadtheir initial test in the Naples epidemic of 1943, and the principle was there estab-
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lished that troops could operate with relative safety in typhus areas; thetheater had only 16 cases during 1942-45.
The six leading causes of death due to infectious andparasitic disease were in the following order: Malaria with 3.84 deaths perannum per 100,000 average strength; tuberculosis, 3.51; infectious hepatitis,3.39 (1944-45); poliomyelitis, 2.49; bacterial pneumonia, 1.89; andmeningococcal 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 otheroverseas command. No deaths were reported for nonpulmonary tuberculosis, whichwas unique among the nine major commands. This form of tuberculosis accountedfor about a fourth of all tuberculosis deaths overseas and more than a third incontinentalUnited States.
The admission rate of bacterial pneumonia was thegreatest of any theater of operations; the death rate, 2.05 per 100,000strength, was second only to that of the China-Burma-India theater. No theaterhad the admission rate of continentalUnited States for bacterial pneumonia, 2.54 per 1,000 strength. For all troops overseas, theadmission rate was 1.26. Death rates for continentalUnited 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 1,000over the 4 years were second only to the rate in the China-Burma-India region.
The dysenteries were extremely prevalent with acombined incidence rate of 21.76 for bacillary and unclassified dysentericdisease. Amebiasis reached the appreciable rate of 8.08 per 1,000, again secondonly to China-Burma-India. Food poisoning was prevalent in 1944.
The theater record for gonococcal infection was good, butchancroid was at high levels of 19.41 per 1,000; syphilis ranked well up amongall major commands of the Army with a rate of 13.48. The incidence oflymphogranuloma venereum (1.94 per 1,000) was higher than in any other theateror area except the China-Burma-India theater.
The area, featured an incidence of 30.09 for sandflyor pappataci fever, the highest rate among commands by a large margin. Casesnumbered 4,399. An individual theater characteristic was the presence ofleishmaniasis with incidence of 1.93 per 1,000 and 282 cases reported. Thedisease appeared in 6 other theaters, and 22 cases are in the, records ofconinentalUnited States as first recognized there. In all, there were some 497 cases in the entireArmy, 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 andparasitic diseases departs greatly from any thus far noted. In order, theywere malaria (8.21), poliomyelitis (5.47), and smallpox (3.42), followed bytuberculosis, bacterial pneumonia, and diphtheria, each with rates of 2.05 perannum per 100,000.
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China-Burma-India Theater
The exigencies of war that required operation of foreigntroops in the area included within the China-BurmaIndia theater brought all thesupport necessary to the emphasis placed by military medicine on thecommunicable diseases. To those not previously acquainted with this generalregion, realization comes quickly that there are parts of this universe in whichthe communicable diseases certainly are not conquered.
First consideration is given to those two communicablediseases which are responsible the world over for most deaths and disability andwhich 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 ofWorld War II in the Far East. The admission rate for bacterial pneumonia was third among theaters ofoperations, preceded by the Middle East and Mediterranean areas. The death rate, however, was measurably in excess of any other andindeed was close to twice that of continentalUnited States, which, as will be recalled, was itself greater than for the theaters, alltroops outside continentalUnited States.
The incidence rate for tuberculosis, all forms, was 0.98 per1,000 average strength compared with 0.92 for all overseas troops and 1.48 fortheUnited States. Death rates per annum per 100,000 average strength were 3.88, similar to therate for all units serving abroad (3.87) but higher than in the United States (2.64).
The theater had its difficulties with the venerealdiseases. The incidence of gonorrhea was satisfactorily low, well below averagefor troops at home or abroad. Lymphogranuloma venereum, however, had the highestincidence rate among theaters or the Zone of Interior with a rate of 2.50 per1,000. Syphilis was well above average for soldiers serving abroad and so waschancroid, each by about one-half.
The theater had the top malaria rate among major commandswith an incidence of 86.70 per annum per 1,000 over the war period.
The intestinal infections were uniformlyfrequent.Typhoid fever totaled 78 cases and paratyphoid 96. The incidence ofdysentery, as judged by data for bacillary and unclassified forms but far from acomplete rate, was 21.19 per annum per 1,000 strength; the Middle East being theonly 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 placewith 6.67 per 1,000.
The highest incidence of poliomyelitis among theaters was inChina-Burma-India, and the disease in general was more, frequent abroad than athome. The general list of parasitic diseases was enhanced in frequency, and notheater had more fungus infections. Complete data for hepatitis are not at hand,but those available indicate the disease occurred at close to average level fortroops of all theaters.
The China-Burma-India theater had its individualproblems. Sandfly fever was a fairly common disease with 2,941 cases giving arate of 6.71 per
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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 18.74per 1,000. Scrub typhus enters the list of diseases thus far recorded with 804cases, the incidence rate 1.83 per 1,000. The average annual death rate forscrub typhus in the China-Burma-India theater topped that of any othercommunicable disease in any theater of World War II.
That the infectious and parasitic diseases need to bejudged in terms other than those referable to theUnited States is well demonstrated by the principal causes of death among diseases of thisclass as recorded in this Far Eastern experience. First on the list is scrubtyphus, 14.60 deaths per 100,000 troop strength. Next in order are malaria,9.12; poliomyelitis, 8.21; smallpox, 4.56; tuberculosis, 3.88; bacterialpneumonia, 3.19; and meningococcal meningitis, 2.05. The items included and thevalues themselves are rather startling. For a number of these diseases, sharpirregularities in annual rates of occurrence mark the coming and going ofepidemics.
Southwest Pacific Areas
The part of the world that includes the Southwest Pacificareas rivals the China-Burma-India area in frequency of communicable disease; ifanything, the variety is greater. This Army area had a part in the influenza of1942. Tuberculosis and bacterial pneumonia were at average levels for overseastroops. The record in respect to the venereal diseases was good, even forlymphogranuloma venereum and chancroid, which was a creditable achievement inthis environment.
The main difficulty was with malaria, for the theaterhad an average of 57.07 cases per annum per 1,000 average strength during thewar period. No less than 104,809 cases are included in the medical records ofthe command. A proverbially endemic disease, malaria was epidemic in 1943 whenthe incidence rate for the year reached 209.56 per 1,000 strength. Energeticcontrol measures resulted in a wholly satisfactory record the next year and alow 33.58 in 1945.
Mumps, as would be expected, was first among the commoncommunicable diseases of childhood, but a moderate epidemic of rubella in 1942was an unusual event which carried into the following year. An epidemic ofdiphtheria, 505 cases, occurred in 1945.More cases of poliomyelitis (224) werereported than from any other theater, the incidence being 0.12 per 1,000 averagestrength.
The full data on infectious hepatitis are not available, butthe 36,110 admissions in 1945, making a rate of 34.85 per 1,000, was notduplicated in any theater during this or the preceding year. Even in 1944 inthis theater there were as many as 4,966 cases, the rate being 9.21. In theSouthwest Pacific areas, deaths due to infectious hepatitis averaged 8.44 perannum per 100,000 during 1944-45.
Leishmaniasis with 29 cases, 5 cases of rabies, 70 ofarthropodborne encephalitis, and 20 cases of yaws gave variety to the largerevents just recorded.
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Deaths per annum per 100,000 average strength for theSouthwest Pacific Area gave first place among infectious and parasitic diseasesto 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 asbizarre as that of the ChinaBurma-India theater to those who are accustomed towestern public health problems.
Dengue fever was another prevalent disease of the SouthwestPacific. A total of 50,903 cases occurred; the over-all annual incidence ratefor 1942 to 1945 was 27.72 per 1,000.The, epidemic year was 1944 with 28,292cases and an annual rate of 52.47; 1942 had rates even higher, but fewer numberswere involved. Only a favorable situation in 1945 permitted the average ratescited.
The dysenteries were commonly present as would beanticipated. Bacillary and unclassified dysentery together gave a total theaterrate of 9.73 per annum per 1,000. Amebiasis had a rate of 6.67 with some 12,244cases reported; most of them, 11,475, occurred in the final year of 1945, withthe evident implication that actually there had been more cases in other yearsthan had been recognized. Typhoid fever accounted for 73 cases, and paratyphoidfever for another 183 cases. Food poisoning was more common than for overseastroops in general.
Scrub typhus was a special feature of communicable diseaseoccurrence in this theater. Of 5,436 cases reported from all theaters ofoperations, 4,459 were in the Southwest Pacific, average annual rates being 2.43per 1,000. Fleaborne typhus was present to the extent of 87 cases, but there wasno louseborne typhus.
The parasitic diseases were common, particularlyhookworm and ascariasis. There were some 323 admissions for filariasis, 233 ofthem in 1944; over-all theater rates were 0.18 per 1,000. Schistosomiasisaccounted for 1,545 cases, rate 0.84, with 1,460 cases in the single year of1945. 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, tothe venereal diseases was outstanding; it was second only to the record in theNorth 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 eachinstance, with the exception of chancroid, markedly below the average for troopsoverseas (table 10) or at home.
The incidence rate for tuberculosis was about equal tothe average rate for overseas troops, but the rate for bacterial pneumonia waslower than rates for all other overseas areas.
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As in the Southwest Pacific Area, malaria was the mainproblem, and the history of events was much the same in the two theaters. Duringthe first year, the number of cases was small because of the limited time ofexposure and the small troop strength, but in 1943 cases numbered 55,050 and therate per 1,000 was 188.81, not dissimilar to that of Southwest Pacific in thesame year. The recovery was more prompt, however, for the incidence rate in 1944was 24.33 and the last year of the war had the excellent record for thatlocality of 22.48 per 1,000.
The intestinal infections were the next broad problem.The dysenteries of recognized form, bacillary and unclassified, prevailed in afrequency of 5.58 per 1,000; the main difficulty appeared in the initial year of1942, and progressive improvement thereafter gave a rate in 1945 of 3.43 per1,000. Food poisoning was of noteworthy frequency in the years after it wasestablished as a reportable condition; in 1945 there were 1,205 admissions and arate of 3.21 per 1,000.Amebiasis (rate 2.50) was less commonly recognized thanin the Southwest Pacific (rate 6.67 per 1,000). Typhoid and paratyphoid feverfever cases were 28 and 33, respectively.
In the Central and South Pacific area, dengue came close tomatching its behavior in the Southwest Pacific, rates for the Central and SouthPacific being 23.83, and in the Southwest Pacific 27.72 per 1,000. The diseasewas epidemic in both 1943 and 1944, a total of 28,092 cases being reportedduring the 2 years.
Although the incidence of infectious hepatitis washeavy, it was much lower than in the Southwest Pacific. Both parasitic andfungus diseases were prominent. There were 171 cases of scrub typhus, but thisdisease was of no significance here compared with the other Pacific theater;fleaborne typhus was more frequent than in any other theater, but there wereonly 123 cases.
This theater was characterized by the preponderance offilariasis; 1,348 admissions were reported, most of them in 1943 and 1944. TheSouthwest Pacific had far less, but even in the Central and South Pacific therate was only 1.07 per 1,000 average strength. The 116 cases of schistosomiasiswere a minor event in comparison with the observed frequency of that disease inthe Southwest Pacific Area. It was in this area that one of the two admissionsfor glanders in foreign theaters was reported, the other being in the Middle East theater.
Diphtheria appeared in minor epidemic proportions inthe last 2 years of the recorded period.
The six leading causes of death due to infectious and parasiticdiseases 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 ratesare 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 subtropicalregion on the other side of the world from the two Pacific theaters. Comparisonis scarcely productive for the theater was small and singularly free from combataction and the associated field conditions. The incidence of communicabledisease and the deaths from infection are instructive in respect to what can beaccomplished with modern preventive services under environmental conditions thatprovide more than usual risk.
Tuberculosis death rates and the incidence and death ratesfor bacterial pneumonia were favorable; these two communicable diseases leadalmost all other infectious processes in temperate zones as causes of death andrank high almost everywhere.
Incidence of the venereal diseases was high. Gonococcalinfection ranked close to the top for all theaters, and occurrence of syphiliswas much above the average. Chancroid was at, the high level of 12.19 per 1,000strength, and lymphogranuloma venereum had a rate of 1.60 per 1,000, three timesthat for theaters in general and more than twice the home incidence. Onepeculiarity marked this experience in control of the venereal diseases. Theusual pattern is one of initial difficulties, subsequent improvement in ratesuntil the war ends, and then an incidence even greater than before. The LatinAmerican 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 thistheater. The total wartime experience ended with a rate of 41.01 per 1,000 peryear, but the first year was responsible for most of this with an annual 1942rate of 99.78. The improvement that followed was remarkable, and 1945 ended withan incidence rate of 8.17 per 1,000 average strength.
Intestinal infections were at high risk, but the rate forrecognized dysenteries was good, 1.72 per 1,000 per year. Parasitic infectionswere relatively frequent among infections as a whole. Ten cases of typhoid feveroccurred and seventy of paratyphoid. Infectious hepatitis was at a low level.
A series of epidemics of rubella was an unusualoccurrence, the annual rate for the 4 years being 5.14 per 1,000, with 9.82 in1945. Only in continentalUnited States was this disease relatively so prevalent; in the Latin American area, rubellaexceeded both mumps and measles.
Poliomyelitis was represented in this theater by 13 cases and3 deaths for the 4 years. The theater had 1 of the 6 cases of rabies in overseastheaters. Sandfly fever provided a minor problem with 35 cases.
The deaths from infectious and parasitic disease inthe Latin American area are again a curious collection as judged by conditionsin continental United States for they rank in order as follows: Malaria, 4.72per annum per
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100,000 average strength; tuberculosis, 2.63; bacterialpneumonia, 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 recordfor death and disability from disease, all forms, and from communicablediseases; indeed, the theater far outdistanced all others. The venereal diseaseswere at an unbelievably low level, uniformly for all major categories andthroughout the 4 years. The usual increase in the last year of the war occurredhere but served only to bring the rate for gonococcal infections to 10.43 perannum per 1,000 and for syphilis to 3.97.
The 1942 and 1943 experience with influenza was muchthe same as in all theaters, but the disease continued through 1945 as the mostfrequently occurring item of the infectious and parasitic list, in all 6,165cases. Bacterial pneumonia was infrequent.
A small outbreak of meningococcal meningitis in 1943 was oneof the few epidemic events.There is little to note but a good record.
Causes of death from infectious and parasitic diseasewere 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 reporteddeaths, 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 transportedfrom reservoir to susceptible human host are a fundamental factor in designingmethods for the control of the communicable diseases. Modes of transmissionserve as a logical means for classification of these disease processes. Table 12shows 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 therespiratory tract was more than two and one-half times the rate for all overseasareas. The Far East and Pacific theaters had notably low rates, with other theaters occupying amiddle position except for the North American theater which had rates of 26.13per annum per 1,000 average strength. It is reaffirmed that common respiratorydisease is not included.
Intestinal infections showed greater variation betweentheaters than did the respiratory infections. The rate for Zone of Interiortroops 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 belowthose of continentalUnited States. This circumstance, along with correspondingly low rates for arthropodborneinfection, accounts in large part for the over-all good record of these twotheaters. The annual incidence of 0.84 per annum per 1,000 for intestinalinfections in the North American theater is in contrast
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TABLE 12.-Incidencerates 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. Othertropical areas also had high levels of intestinal infection; the rates of the Mediterranean and Central and South Pacific theaters deserve commendation considering theenvironmental conditions under which troops operated.
The venereal diseases have been compared in discussion ofthe theaters. Scabies is the main component of contact infections listed as"others."
Malaria mainly determines the extent of the arthropodborne group ofdiseases; one-fourth of mankind lives in malarial zones and United States Armytroops were engaged in most of the places where malaria flourishes.Dengue andsandfly fever were other important elements. Malaria and scrub typhus were thechief contributors to the number of deaths.
Epidemic hepatitis was the important disease in theclass of infections where mode of transmission remains uncertain, notably sowhen serum hepatitis is included as in this instance. In general, theincidence rates, shown in table
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12, are representative of infectious hepatitis (including some serumhepatitis), since the incidence of the other three diseases in this category(infectious mononucleosis, acute poliomyelitis, and lymplrocyticchoriomeningitis) was relatively low.
INTERNATIONALLY QUARANTINABLE DISEASES
Never in the history of warfare has an army traveled sofar or so widely as did troops of theUnited States during World War II. Never before has an army been called upon to take upoccupational duties in such farflung parts of the world. No recognized focus ofthe great pandemic diseases of history was untouched by American interest andinfluence nor unvisited by American soldiers.
Not only was the amount and extent of travel by UnitedStates Army troops greatly increased during the war, but it was potentially moredangerous travel. Compromise of established measures for internationalquarantine is unavoidable in time of war. Civilian health staffs of countries atwar are depleted. Necessary supplies for prevention and control of disease amongcivilian populations are directed in considerable part to military needs. Newlydeveloped methods are at the first disposal of the military. Port controlin invaded countries was invariably taken over by the occupying enemy forces;when these areas were liberated, port sanitation was usually found to be totallydisorganized. Many ordinary regulations and procedures in respect to air and seatraffic were abrogated or modified because of military necessity; others weredisregarded through license, ignorance, or exigency. There was a greaterpotential health risk in international travel during the war and greaterpossibility of the spread of the quarantinable communicable diseases. The recordwas astonishingly good. It will now be considered having been purposely avoidedin the presentation of problems of individual theaters.
The six internationally quarantinable diseases are cholera,plague, yellow fever, louseborne typhus fever, louseborne relapsing fever, andsmallpox. In World War II, 3 of the 6 (cholera, louseborne typhus fever, andsmallpox) definitely appeared in various major commands of the Army. Inaddition, 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 ratwas found in an American ship. The data for the Army as a whole and according totheaters of operations are given in table 13. The four diseases, cholera,louseborne typhus, relapsing fever, and smallpox, accounted for 402 cases and 32deaths among troops of the Army as a whole. All theaters and areas had someexperience with at least 1 of the 4 diseases. The China-Burma-India theater hadexperience with all four.
Relapsing fever was of commonest occurrence, for itappeared in home troops and in all theaters with the single exception of theEuropean theater. There were no deaths. The Mediterranean theater accounted for49 cases, an admirable record in view of the extensive epidemic that occurred inthe
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TABLE 13.-Internationally quarantinablecommunicable diseases, U.S. Army, by theater orarea, 1942-45
civilian population of the area. The greatest number, 70, was in theChinaBurma-India theater; aside from 28 cases in the United States and 13 casesin the Middle East, the remainder was scattered sporadic infection.
Smallpox was next in frequency, with 117 cases and 30deaths. The number of deaths indicates that the disease in most instances wasvariola 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 intheaters of operations.China-Burma-India had 33 cases and the 2 Pacific areasalmost equal numbers. Only the European and North American areas had nosmallpox.
The limitation of louseborne or classical typhus fever to 104cases and no deaths was one of the remarkable achievements of preventivemedicine 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 circumstanceswere not dissimilar from those of other wars whose outcome typhus fever sofrequently has decided. In World War 1, 1914-18, and the immediate periodthereafter, more than 5,000,000 persons had typhus fever in Russia alone, anddeaths 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 a6-month period in 1915. In the European theater, in this war, American troopsentered a region inGermany that had at the time about 17,000 cases among the civil population anddisplaced persons. The United States Army escaped with 10 cases and no deaths.
Cholera under ordinary circumstances is endemic onlyin the China-Burma-India theater among the eight principal divisions ofterritory its which the United States Army operated overseas. The disease hasgreat potentiality for spreading; it has repeatedly ranged far afield from thisendemic focus and on several occasions has invaded continental United States in epidemic proportions. Ten cases of cholera occurred among American troops ofthe China-Burma-India theater with two deaths, a usual fatality for cholera.There was much cholera in bothIndia andChina 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. Allbut two of them invaded one or more of the great command areas; no theaterescaped visitation by at least one of them. None gained a foothold. The risk wasreal. Here then is further justification for the emphasis on communicablediseases in military preventive medicine.
INFECTIOUS AND PARASITIC DISEASES OF ESSENTIAL MILITARY SIGNIFICANCE
The close relationship of communicable disease andmilitary operations has been so long recognized, so decisive in militaryhistory, and so stressed in military planning as to be accepted doctrine. Theseriousness of a given disease in respect to death and disability may be theissue.A relatively mild condition may attain importance because of thenoneffectiveness it engenders. Much depends on the nature of existing militaryoperations. In this war, an outbreak of mumps had disorganized a trainingprogram. Epidemics of acute upper respiratory infection complicated movements oftroops on long long journeys. An undue prevalence of so benign a disease asscabies interfered with preparations for marshaling an invasion. Dysenterydisrupted a campaign, and the German general staff could speak feelingly ofepidemic hepatitis its Africa. Typhus fever threatened again to settle the outcome of a war to become, asHans Zittsser has remarked, a more potent influence than generals.
Thecommunicable diseases transmissible by way of the respiratory tract fall intotwo main groups, those involving the respiratory tract itself and those leadingto general infection with various localization. The first group always hasimportance.
Fortune favored this war in respect to influenza. Thedisease was present in excessive amount in 1942 and 1943. Influenza A waspandemic in proportions but mild in form. This was a major consideration in theuniformly 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 populationsstationed in warm climates, such as China-Burma-India with 3.19 per100,000 and the Middle East with 2.05, than in the temperate zones of continentalUnited States and the European theater, which reported rates of 1.23 per annum per 100,000.
Tuberculosis failed to maintain its established placeas a cause of death and disability in military populations because of theeffective screening of recruits at the time of induction.
The diseases of the respiratory group leaving localizationother than in the respiratory tract itself failed to reach the statisticalexpectancy warranted by experience of previous wars. Mumps, the usual leader innumbers of cases, was outdistanced by rubella. The incidence of mumps wasconsiderably lower than it lead been in World War 1, while the rubella rate wasslightly higher. The incidence of meningococcal meningitis, justifiablyrecognized as a military disease, was only 0.51 per annuum per 1,000 for the,total Army and 0.67 for continentalUnited States.
The record for intestinal infections was remarkably good,considering the long history of these diseases as the primary concern of campand field. During the 4 years of war, the European theater had only two deathsfrom bacillary and unclassified dysentery combined, and operations were on abattleground where thousands have died of this cause in other wars.
Typhoid fever illustrates the effect of environment in theface of similar methods of prevention and control; 91 cases occurred incontinentalUnited States and 414 overseas, with rates of 0.01 and 0.04 per 1,000 averagestrength. The death rate for typhoid fever was relatively much greater inforeign operations, for 3 deaths occurred among home troops and 33 overseas.
Amebiasis was more costly in this war because of the manytropical areas in winch troops operated; the same is true for infections byintestinal protozoa other than Entamoeba histolytica. The disabilityengendered through food poisoning cannot be well determined from the existingdata, for food poisoning was not reported as such until 1944, and even thenacceptance of the new direction for reporting was not immediate; previously,cases were usually included among the diarrheas and dysenteries. Indication isthat this condition continued as a common cause of disability, despite theimprovements in camp sanitation and nutritional practices.
The data cited in table 12 and the accounts of individualtheaters show that the venereal diseases were still a main feature ofmedicomilitary practice; the records were better than in some outer wars, butmuch remains to be done before control can be considered adequate orsatisfactory.
Fungus infections took on new importance withoperations in tropical countries, where mycosis of the feet interfered withmilitary effectiveness and specific fungus infections were relative frequent.Coccidioidomycosis was a special problem of troops in theUnited States.
Schistosomiasis and filariasis were military infections newto most military physicians of this war and were responsible for much disabilitybefore control
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was effected. Scabies, that common accompaniment of troops, had aninteresting history in that admission rates progressively increased as the warcontinued; 1942 had a rate for overseas troops of 2.03 per 1,000 which increasedin successive years to 2.84, 3.08, and 5.48. At home, rates were similar tothose overseas, although the spread between first and final years was greaterfor domestic troops, the rates being 2.38 in 1942 and 7.60 in 1945. Theexperience of the United States Army in World War I was repeated in World WarII, and the problem of prevention of scabies still remains unsolved. Progresshas been made, however, in the control of infestation by lice. Admission rateswere 0.32 per annum per 1,000 in continentalUnited States and 0.18 overseas. The degree of louse infestation in the AmericanExpeditionary Forces in 1918 was estimated to be 1 to 2 percent, but thesignificant feature is that in both regions rates declined in the sameprogressive fashion as they rose for scabies. The new insecticides give improvedmethods for control.
The arthropodborne diseases introduced a fresh elementinto historicalUnited States military practice. Malaria was the chief problem. Troops had of course operatedbefore in malarious regions and had developed effective control, for instance,inPanama. A new situation was encountered, however, when field operations had to becarried on both in unfamiliar environments and in many places where malaria washyperendemic. The initial costs of this disease were heavy, but the finalresults were good. Filariasis, scrub typhus, and sandfly fever also posedrelatively new problems. Dengue had almost been forgotten, especially the factthat it could reach such epidemic proportions as developed in the Pacifictheaters.
Infectious hepatitis has had a part in war before but neverto the same extent as in World War II, in which was added the furthercomplication of serum hepatitis.
The results attained in control of tetanus, a diseaselong recognized as a peculiar hazard of war, are so striking as to deservespecial mention. In the European theater where battle casualties were morenumerous than in any other theater, both the mortality and the morbidity rateswere approximately the same as those for troops stationed in continental UnitedStates, thousands of miles from a battlefield. The almost unbelievably goodresults, a single case and a single death during the whole period of operationsin Europe, are attributable to the remarkable effectiveness of active immunizationbrought about by tetanus toxoid. Eight cases in the Zone of Interior wererelated to tetanus infection among recruits, principally before immunization hadbeen accomplished. Only four cases of tetanus occurred among all troopsoverseas.
ACHIEVEMENTS AND CHALLENGES
Many new problems come to light in the course of anexperience as broad as that described in this chapter. The development ofadministrative measures and the search for new knowledge on which those measuresdepend 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 theachievements of the war years fills many pages in these volumes on infectiousdiseases. The stimulus continues. No one of these problems was wholly solved butwhat 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. Forinstance, FortBragg fever was eventually found to be a form of leptospirosis. Clinical variants andimmunological 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 amongtroops, 13,571 admissions in continentalUnited States and 4,961 abroad. A significant feature was that rates rose each year for bothgreat groups of troops, in theUnited States from 0.29 in 1942 to 1.71 in 1945, and overseas from 0.23 to 0.58 per annum per1,000 average strength.
Lymphocytic choriomeningitis was present amongdomestic 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 numbered425 for the same 3 years, 260 leaving occurred in 1945, primarily in Europe and the Mediterranean areas, but with all theaters represented, even theexemplary North American area. The disease is worldwide in its distribution,and, with due allowance for unconfirmed diagnosis, seemingly more frequent thanordinarily recognized.
The behavior of herpes zoster and chickenpox in this group ofyoung adults, both at home and abroad, warrants further analysis. Like othercommunicable diseases of childhood, chickenpox is a fairly frequent infection oftroops, especially recruits, less so than mumps and measles but more thanwhooping cough. Among troops stationed in continental United States, 8,555 cases of chickenpox occurred, but the returns also give 5,384 admissionsfor herpes zoster. Compared to continentalUnited States, chickenpox was one third as frequent among overseas troops, but herpes zosteroccurred more frequently. Overseas, the 2,109 cases of chickenpox were exceededby the 4,735 admissions for herpes zoster.
World War 11 involved more men and extended over awider geographical area than any other war in history. The successful resultthat accrued to American arms was influenced in forceful degree by favorablecasualty rates for the communicable diseases, rates that have no precedent.
The actual experiences of this war justify the firm emphasiswhich military medical officers continue to place on the significance of thecommunicable diseases. These experiences included the repeated threat of thegreat pandemic diseases; the occurrence of epidemics oven under the best ofconditions; and the strange problems brought by modern warfare, characterized asit is by rapid movement and wide dispersal of resources. Well-known infectiousdiseases, typhoid fever for example, carefully evaluated and adequatelycontrolled under conditions of the American environment take on new significancewhen 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 isthe steady erosion of manpower brought about by everyday infections, losseswhich become evident when communicable disease is measured in terms of noneffectiveness and of the permanent injury which leads to lasting disability. Thedeaths that these diseases cause are not the sole concern, nor do they alwaysprovide a reasonable basis for judgment, in both the military and civilianpractice of medicine and public health.
