History

CHAPTER I

Respiratory Diseases

Yale Kneeland, Jr., M.D.

GENERAL CONSIDERATIONS

Diseases of the respiratory tract may be divided into two groups: The acuteinfections and the chronic diseases which may or may not be infectious. Most ofthese conditions will be dealt with in this chapter, although certain exceptionswill be made. For example, in World War II, the interrelationship oftonsillitis, scarlet fever, rheumatic disease, and nephritis was intensivelystudied; the subject of streptococcal infections as a whole will be discussedelsewhere. Similarly, two chronic infections, tuberculosis andcoccidioidomycosis, will be described by others. Lastly, chronic sinusitis,aero-otitis, and the like, are primarily the concern of the otologist and willnot be considered here.

The acute respiratory diseases which immediately come to mind are the commoncold, influenza, and pneumonia. These are communicated by droplets and dropletnuclei and are thus allied to certain virus infections, such as measles, whichare also presumably transmitted in this way. Certain communicable diseases ofchildhood will also be included here. Cerebrospinal fever and diphtheria,however, although their portal of entry is the respiratory tract, will bediscussed elsewhere in this volume. Clinical syndromes of unknown etiology,bizarre manifestations occurring only in localized outbreaks and not generallyrecognized as disease entities, are not included. This still leaves a largefield for discussion.

Any general consideration of disease in World War II immediately invitescomparison with the experience in World War I. Exact comparisons of morbidityand mortality of acute respiratory diseases in the two wars are not, however,possible for two reasons: First, more exact knowledge of the diseases led to achange in terminology; and second, certain new concepts, for example, that ofatypical pneumonia, evolved. In spite of this, a rough and startling comparisonmay be made of the 46,640 deaths from influenza, lobar pneumonia,bronchopneumonia, bronchitis, and measles in the First World War,¹roughly 73 percent of total deaths from disease, and the 1,285 deaths from thesame causes in the Second World War when an army well over twice the size ofthat of World War I was mobilized for a longer period.

Factors which played a role in this extraordinary change in importance of thedisease just mentioned were the advent of sulfonamides and anti-

¹The Medical Department of the United States Army in the World War. Washington: U.S. Government Printing Office, 1928, vol. IX.

biotics, the absence of pandemic influenza of the 1918 type,an apparent change in the whole pattern of respiratory infection between thewars, and a greater degree of immunity to certain communicable diseases in thegeneral population. The last was probably brought about by greatly increasedcommunications which lessened isolation of rural areas. In addition, the almostuniversal roentgen examination of the chest at induction undoubtedly lowered theincidence of chronic pulmonary diseases found in troops during World War II.

In the following pages, the occurrence and course of eachdisease in question during World War II is discussed, with emphasis placed uponproblems of diagnosis, treatment, and general management which were significantin a military sense. The chief military significance of many of the acutecommunicable diseases is epidemiological, and this aspect of the question hasbeen exhaustively presented in other volumes in the history of the MedicalDepartment in World War II.² It is obvious thatin many instances information will overlap. Some of the material will ofnecessity be repetitious.

Insofar as possible, proper names are avoided in the text,but where published material has been drawn upon, full acknowledgment is given.Other sources employed are as follows: Preliminary data from the MedicalStatistics Division, Office of the Surgeon General; the writer's own notes whilehe served as consultant in an oversea theater; essential technical medical datasent in by various theater surgeons; reports submitted by medical consultantsthroughout the world; and other unpublished notes, manuscripts, and memorandumsin the Professional Service Division, Office of the Surgeon General.

Part I. Acute Respiratory Diseases

COMMON UPPER RESPIRATORY INFECTION

Introduction

The term "common upper respiratory infection"includes a heterogeneous group of ill-defined conditions. In fact, it is a kindof scrapbasket which encompasses all the acute respiratory diseases aftereliminating the pneumonias and influenza. In a general way, the group includesthe common cold; nasopharyngitis which may or may not be due to the influenzavirus; infection of the pharynx and tonsils produced by certain micro-organisms,such as the hemolytic streptococcus and Vincent's organisms; and bronchi-

²(1) Medical Department, United States Army. Preventive Medicine in World War II. Volume IV. Communicable Diseases Transmitted Chiefly Through Respiratory and Alimentary Tracts. Washington: U.S. Government Printing Office, 1958. (2) Medical Department, United States Army. Preventive Medicine in World War II. Volume V. Communicable Diseases Transmitted Through Contact or By Unknown Means. Washington: U.S. Government Printing Office, 1960. (3) Medical Department, United States Army. Preventive Medicine in World War II. Volume VI. Communicable Diseases: Malaria. [In press.] (4) Medical Department, United States Army. Preventive Medicine in World War II. Volume VII. Communicable Diseases: Arthropodborne Diseases Other Than Malaria. [In preparation.]

tis. The latter is a loose term limited by some physicians tocases in which dry rales are audible; that is, the asthmatic type, while othersmay use it to describe an acute respiratory infection with substernal sorenessand paroxysmal cough. It is probable that the viruses of common respiratorydiseases, influenza, and atypical pneumonia can all produce this clinicalpicture, and it may also be the result of infection by such organisms aspneumococci or Hemophilus influenzae following a cold. In any cases, itis not an etiological entity.

The common cold had been shown before World War II to be primarily a virusdisease.³ Experimental studies are handicappedby the fact that only man and the anthropoid ape are susceptible to the virus,and such questions as that of immunity and whether the virus is an entity orwhether several distinct viruses exist were not settled. The Commission on AcuteRespiratory Diseases of the Army Epidemiological Board (Board for theInvestigation and Control of Influenza and Other Epidemic Diseases in the Army)during the war undertook, under the direction of Dr. John H. Dingle, toinvestigate the transmission of common respiratory diseases. Evidence wasproduced⁴that there are at leasttwo viruses: One, the coryzal type with a short incubation period, producinglittle if any active immunity; the other, with a longer incubation period,giving rise to more constitutional symptoms, often attended by fever, andconferring immunity against homologous reinoculation. The second type came to beknown as "undifferentiated respiratory disease." As the number oftransmission experiments was small, there is no information as to the relativefrequency of infection with these two agents. Recent observations by Atlas⁵suggest that more viruses of common respiratory infection may exist.

The presence of pathogenic bacteria in the upper respiratorytract adds to the complexity of the etiology of common respiratory diseases.Purulent complications, such as otitis and sinusitis, are due to bacterialinfection, but there is no proof of the role played by identified pathogenicorganisms in the production of subacute catarrhs, sphenoethmoiditis, and thelike. The best opinion during the war, confirmed by the use of chemotherapeuticagents in adults,⁶ was that the average cold isa fairly pure virus disease, but that the relationship of virus to bacteria wasoften not clear.

Colds are, on the whole, more serious in infants than in adults. Infantsusually develop a fever with a cold, and complications are more frequent.

³Dochez, A. R., Mills, K. C., and Kneeland, Y., Jr.: Studies on the Common Cold; Cultivation of Virus in Tissue Medium. J. Exper. Med. 63: 559-579, April 1936.
⁴Commission on Acute Respiratory Diseases: Experimental Transmission of Minor Respiratory Illness to Human Volunteers by Filter-Passing Agents. I. Demonstration of Two Types of Illness Characterized by Long and Short Incubation Periods and Different Clinical Features. II. Immunity in Reinoculation With Agents From the Two Types of Minor Respiratory Illness and From Primary Atypical Pneumonia. J. Clin. Investigation 26: 957-973; 974-982, September 1947.
⁵Atlas, L. T.: Minor Respiratory Diseases; Studies With Four Agents in Human Volunteers. Abstract in J. Clin. Investigation 32: 552-553, June 1953.
⁶Cecil, R. L., Plummer, N., and Smillie, W. G.: Sulfadiazine in the Treatment of the Common Cold. J.A.M.A. 124: 8-14, 1 Jan. 1944.

Various pathogenic bacteria are more conspicuous in culturesmade from children,⁷ and this suggests thatthey may have some influence on the severity of colds even in the absence ofdefinite purulent complications. Controlled studies made during the early waryears of the use of sulfonamides in very highly susceptible children supportthis concept.⁸

It was the writer's impression that soldiers reacted to common respiratorydiseases in a manner more suggestive of childhood than of adult life. Theytended to develop fever of higher degree than that seen in general civilianlife. Youth, exposure, and crowding probably contributed to this clinicalpattern. Incidence of infection with the virus of undifferentiated respiratorydisease may have been higher in the Army than in civilian life. Whatever thereasons, the acute phase of the common cold was apt to be more prostrating tosoldiers than to office-working civilians. However, the soldier's convalescencewas usually rapid.

Severe throat infections caused by the hemolyticstreptococcus, scarlet fever, and rheumatic fever will be discussed elsewhere.However, a certain proportion of admissions to the respiratory service of anArmy hospital were infections caused by this organism. Various complications tothe usual sore throat or inflammation of the lymphatic tissue are recognized,but in the Army the most common was peritonsillar cellulitis.

The clinical picture of exudative pharyngitis is wellrecognized, and when an acute tonsillitis or pharyngitis is observed showingwhitish exudate, most physicians assume it is caused by hemolytic streptococci.However, when endemic exudative pharyngitis was studied closely by theCommission on Acute Respiratory Diseases,⁹ inonly about 50 percent of cases could the hemolytic streptococcus be recoverd onculture and in only half of these was there a rise in the titer of streptococcalantibody during convalescence to suggest that the organism was playing animportant role in the disease. Since in only 25 percent of the cases of endemicexudative disease was the laboratory evidence for streptococcal infectioncomplete, the Commission designated the other cases as nonstreptococcalexudative pharyngitis, and some speculation occurred as to the possible viralorigin of this condition. Although, in the aggregate, cases of proved hemolyticstreptococcal pharyngitis differ clinically from the nonstreptococcal variety,mild cases may be indistinguishable.

Vincent's organisms may also at times produce throat lesions which resemblestreptococcal infections. The appearance of a typical case of so-calledVincent's organisms differed, however, from that of a streptococcal infection.The thick pseudomembrane and the tendency to ulceration were

⁷Kneeland, Y., Jr., and Dawes, C. F.: Studies on the Common Cold; The Relationship of Pathogenic Bacteria to Upper Respiratory Disease in Infants. J. Exper. Med. 55: 735-744, May 1932.
⁸Siegel, M.: Studies on Control of Acute Infections of the Respiratory Tract. II. Oral Administration of Sulfadiazine at the Onset of Acute Respiratory Illness. Am. J. Dis. Child. 66: 114-120, August 1943.
⁹Commission on Acute Respiratory Diseases: Endemic Exudative Pharyngitis and Tonsillitis; Etiology and Clinical Characteristics. J.A.M.A. 125: 1163-1169, 26 Aug. 1944.

characteristic, but differential diagnosis was not alwayspossible, and it was always necessary to rule out diphtheria. Vincent'sstomatitis presented itself often as only a dental problem, but occasionally thethroat was involved as well as the gums; likewise, Vincent's infection of thethroat without involvement of the gums was also encountered. A comparison of theadmission rates for the various designations of Vincent's infection in WorldWars I and II is presented in table 1.

TABLE 1.-Admissionrates for the various designations of Vincent's infection in the U.S. Armyduring World War I and World War II

[Rate expressed as number of cases per annumper 1,000 average strength]

Diagnostic terminology	Admission rate
	World War I	World War II
	World War I	1942-45	1942-43	1944-45
Trench mouth	0.02	0	1.94	0
Vincent's angina	¹1.56	0	0	0
Vincent's infection (not elsewhere classified)	0	0	2.30	0
Vincent's infection (all forms)	¹1.58	3.93	4.24	3.73

¹Enlisted personnel only.

Experience in the Continental United States
Noneffectiveness

Common upper respiratory infection was the most prolificcause of noneffectiveness in the U.S. Army. A graphic representation of itsincidence in the Army from 1925 to 1945, inclusive, would show a sharp risearound the beginning of each year. An unusual peak was reached around thebeginning of 1941, when no major general epidemic was prevalent. This militarypeak was coincident with a rapid increase in mobilization, the opening of newcamps, and the hurried assembly of large numbers of unseasoned civilians.

A careful statistical analysis presented by Dr. Philip E.Sartwell in another volume in the history of the Medical Department in World WarII shows that the magnitude of incidence of common respiratory diseases in anyarea is related to the proportion of new recruits.¹⁰It is conceivable that the unexpected increment of respiratory infection inrecruits was due to infection with the virus of undifferentiated respiratorydisease; that is, the one which leaves some active immunity in its wake. Theseasoning of troops is of military importance insofar as common respiratorydiseases are concerned as it governs the amount of noneffectiveness to beexpected.

For the remainder of the war, the curve of incidence of common respiratorydiseases in the United States was astonishingly symmetrical. At about

¹⁰See footnote 2 (1), p. 2.

the same time during each war year, there was a recurringpeak of almost the same dimension. Individual differences in type of disease andfrequency at various stations were cancelled out by the large numbers and widegeographic distribution.

Streptococcal infections were particularly numerous in theeastern slopes of the Rocky Mountains and the Great Lakes area. Here, they werethe subject of considerable study both in their less conspicuous form as part ofthe mosaic of common respiratory disease and when they became epidemic and wereassociated with scarlet fever and rheumatic fever. In cases associated withcommon respiratory disease, treatment varied in different stations. The typesand amount of sulfonamides employed differed, although, when available,sulfadiazine was probably the most widely used. Controlled studies¹¹in large numbers of cases indicated that sulfadiazine had no more effect thanthe routine APC capsule on the duration of the febrile period or on the lengthof hospital stay. In more severe cases, however, the drug seemed to limitspread, to lessen cervical lymphadenitis, and to prevent the development offrank abscess.

A study of air disinfection directed by the ArmyEpidemiological Board demonstrated that certain glycols, when vaporized, killedmicro-organisms¹² and also influenza virus.¹³These substances seemed wholly nontoxic in bactericidal concentration, buttheir efficacy was influenced by environmental factors, such as humidity.¹⁴Under clinical conditions, they diminished airborne cross-infection.¹⁵These reports represented progress in the control of infection, but practicallimitations in the application of aerosols prevented their use in the field.Oiling floors and bedding, another method aimed at reduction of airborneinfection, could not be shown to lower incidence of common respiratory infectionat Fort Bragg, N.C.

In summary, common upper respiratory infection, while thecommonest single cause of military noneffectiveness, did not seriously interferewith the training program. Prolonged disability as a sequel was almost entirelylimited to the streptococcal infections. Mortality was insignificant.

Experience Overseas

Incidence-The "transport cold" was a well-known feature ofcrossing the Atlantic in wartime. Its widespread occurrence could be attributedto

¹¹Rusk, H. A., and van Ravenswaay, A. C.: Sulfadiazine in Respiratory Tract Infections; Its Value in Treatment During the Winter of 1942-1943 at Jefferson Barracks, Missouri, J.A.M.A. 122: 495-496, 19 June 1943.
¹²Robertson, O. H., Bigg, E., Miller, B. F., and Baker, Z.: Sterilization of Air by Certain Glycols Employed as Aerosols. Science 93: 213-214. 28 Feb. 1941.
¹³Robertson, O. H., Bigg, E., Puck, T. T., and Miller, B. F.: Protection of Mice Against Infection With Air-Borne Influenza Virus by Means of Propylene Glycol Vapor. Science 94: 612-613, 26 Dec. 1941.
¹⁴Robertson, O. H.: Sterilization of Air With Glycol Vapors. Harvey Lect. (1942-1943) 38: 227-254, 1943.
¹⁵Harris, T. N., and Stokes, J., Jr.: Air-Borne Cross-Infection in the Case of the Common Cold. A Further Clinical Study of the Use of Glycol Vapors for Air Sterilization. Am. J.M. Sc. 206: 631-636, November 1943.

the great crowding, poor ventilation, and the bringingtogether of troops from many different units, thus introducing new infectivestrains. It was commonplace for as high as 80 percent of U.S. troops to contracta cold in the course of the voyage to England.

In spite of the climate in England, colder and damper than that to whichAmericans had been accustomed, the noneffective rate due to respiratory diseaseswas considerably lower there than in the United States. The fact that U.S.troops were seasoned when they arrived undoubtedly contributed to the lowerrate. In some Americans, the cold had a tendency to become chronic, particularlyduring the first year overseas, but usually thereafter the men had becomeacclimatized, and chronic catarrh and cough were much less marked. Individualswith a history of recurrent bronchitis were apt to have difficulty with theEnglish climate; in particular, any tendency to asthma seemed accentuated. Onthe whole, however, the health of the Army was excellent, and there was no undueincidence of sinusitis.

The incidence of common upper respiratory disease and influenza in theEuropean Theater of Operations, U.S. Army, pointed up the result of seasoning oftroops. In November 1943, at the time of the epidemic of influenza A, theincidence was slightly higher than in January 1943 when influenza was notidentified. After November 1943, there was a steady decline so that in June 1944and thereafter throughout the winter of 1945 the noneffective rate was at a verylow level.

Clinical features of common upper respiratory infection in the Europeantheater were not remarkable. Throat cultures yielded moderate numbers of highertype pneumococci and H. influenzae. The number of hemolytic streptococcuscarriers was not large, and only sporadic cases of streptococcal sore throatappeared during the winter months. The tendency to develop peritonsillarcellulitis has been mentioned. In 80 percent of such cases, the hemolyticstreptococcus could be cultivated. The remaining 20 percent, clinicallyindistinguishable, may represent cases of nonstreptococcal exudative pharyngitiswith an unusual degree of swelling of faucial pillars.

The incidence of common respiratory infection in the Mediterranean (formerlyNorth African) Theater of Operations, U.S. Army, was considerably below theaverage for the European theater and for the United States in 1942 and 1943. Inthe summer of 1944, it was slightly higher, but at this time morbidity elsewherewas unusually low. Common respiratory disease presented one special problem inthe Mediterranean theater-the likelihood of its being confused withcertain conditions which were endemic in the area, particularly sandfly fever,malaria, and the preicteric stage of hepatitis. Complications of commonrespiratory infections were not conspicuous, and a total of but 10 deaths wasrecorded from such purulent infections as meningitis.

Incidence of streptococcal infections in the Mediterranean theater was low.According to Circular Letter No. 16, Headquarters, North African

Theater of Operations, Office of the Surgeon, 22 March1944, subject: Preparation of Medical Department Reports and Records, U.S. Army,the term "streptococcal sore throat" was applied only to acutepharyngitis and tonsillitis known or suspected to be caused by the betahemolytic streptococcus, and foodborne and milkborne outbreaks of septic sorethroat. During the 11-month period from 1 May 1944 to 31 March 1945, inclusive,when streptococcal sore throat was reported separately, only 803 cases werereported. Two small outbreaks were studied, one involving 112 men and the other,38. In both instances, it was thought that the streptococcal infection waseither foodborne or milkborne. Interestingly enough, not a single case ofscarlet fever developed as a result of these outbreaks.¹⁶

An acute outbreak of membranous pharyngitis in Sicily, in October 1943, involved96 men, 66 of whom were reported by the local civilian laboratories as havingthroat cultures positive for Corynebacterium diphtheriae. Subsequentinvestigation by the staff of the 15th Medical General Laboratory, Naples,Italy, threw doubt on the diagnosis of diphtheria in this outbreak, and thetheater consultant in medicine later expressed the opinion that in allprobability it was of streptococcic origin. The epidemic was explosive and hadthe character of a foodborne or milkborne infection.

Vincent's angina (as distinct from stomatitis or trench mouth) was reportedonly 990 times from the Mediterranean theater. Nevertheless, the estimatedadmissions for the various types of Vincent's infection numbered about 2,800.

The admission rate for common respiratory infection in U.S. Army Forces,China-Burma-India, was comparable with that observed in temperate climates,although the curve of incidence was relatively devoid of seasonal peaks.Clinical characteristics were stated to be astonishingly similar to those notedin the United States, and the complications as frequent.

The Pacific area is so vast that generalizations about disease therein wouldbe dangerous. Conditions in parts of Australia are quite similar to those intemperate regions elsewhere, and common upper respiratory infection conformed tothe familiar pattern. On small tropical islands, however, the incidence wasstated to be much less under normal conditions, rising sharply with the arrivalof large numbers of troops. Studies have been reported from such areasindicating that the bacterial flora was different from that noted in temperateclimates. One study,¹⁷ for instance, included272 throat and sputum cultures in which pneumococci were found only 7 times. Itwas stated in this report that pneumonia was very infrequent.

¹⁶Report [Final], Lt. Col. Daniel W. Myers, MC, and Maj. Edward deS. Matthews, MC, MTOUSA, to Office of the Surgeon General, subject: Respiratory Diseases in the Mediterranean Theater of Operations, 1945.
¹⁷Norris, R. F.: Symposium on Recent Advances in Medicine: Observations on the Epidemiology and Bacteriology of Acute Respiratory Tract Infections Among the Armed Forces of the Tropical South Pacific. M. Clin. North America 28: 1418-1427, November 1944.

Two U.S. Navy observers¹⁸ stated that atleast 50 percent of the cases of catarrhal fever in a South Pacific Area showedasthmalike manifestations. An eosinophilia of 8 to 10 percent was a commonfinding. The significance is obscure unless it is related to the high incidenceof allergic disorders in the Tropics.¹⁹

Treatment-Treatment of common upperrespiratory infections was symptomatic and lacked uniformity. Apart fromstreptococcal and Vincent's infections, this group is not susceptible tochemotherapy. Nevertheless, it is unquestionable that a great many viralinfections were treated with sulfadiazine. The greater the experience of themedical officer, and the better his facilities for laboratory diagnosis, theless unnecessary sulfonamides were administered. The Professional ServiceDivision advised that sulfonamides should not be employed as a routine measurein the absence of definite indications. In doubtful cases, however, it seemedwise to prescribe them. If certain indications were present, such asleukocytosis, symptoms of otitis media, the presence of pneumococci in thesputum, or the clinical features of acute tonsillitis, sulfonamides, andparticularly sulfadiazine, were employed.

Sulfadiazine was used in the treatment of recognized streptococcal infectionswith prompt effect. It was likewise employed in Vincent's infection.

In the winter of 1945, studies were made, in a number of hospitals inEngland, of the effect of local penicillin therapy, either in the form of athroat spray or more frequently of lozenges containing 500 units of penicillin.Results in streptococcal infections were disappointing. The use of intramuscularpenicillin was also reported in a few hospitals. Its effects in streptococcalinfection were said to resemble those with sulfadiazine. Local and intramuscularpenicillin gave striking results in Vincent's infections in reports fromEngland, but variable results were obtained in a small number of cases ofVincent's angina when penicillin was used intramuscularly in the Mediterraneantheater.

INFLUENZA

Introduction

The word "influenza" has been in general Englishusage since the 16th century to designate irregularly recurring, widespreadvisitations of respiratory diseases, explosive in character and often associatedwith considerable mortality. Its recognition, until the introduction of the newserological methods, rested upon epidemiological and not clinical grounds, andone could not speak of an isolated case.

Good clinical descriptions of these outbreaks are available. Worldwideattention was directed to the disease in 1889 because of its high incidence

¹⁸Schneierson, S. J., and Wilson, W. A.: Unusual Feature of Respiratory Infections in a South Pacific Area. U.S. Nav. M. Bull. 44: 1010-1012, May 1945.
¹⁹Young, C. T., Cook, W. R., and Kawasaki, I. A.: Allergic Rhinitis and Asthma in Hawaii. War Med. 3: 282-290, March 1943.

and the relatively frequent association with fatal pneumoniaduring that epidemic. The influenza bacillus, isolated by Pfeiffer from a numberof those fatal cases, was regarded for some years as the cause of the disease.Pandemic influenza revisited the world in a more devastating form in 1918,toward the end of the First World War. Incidence was very high, distributionglobal, and the mortality appalling. In the U.S. Army alone, 24,664 deaths wereattributed to the disease, and the number of deaths throughout the world raninto millions.²⁰ This catastrophe gave rise toa most intensive scientific investigation of the disease which revealed that thePfeiffer bacillus could not be found in many typical cases of influenzalpneumonia. These pneumonias usually had a mixed bacterial flora, among whichpneumococci and streptococci were prominent. The conclusion became inescapablethat some wholly different agent, not recognizable by ordinary bacteriologicmeans, was the primary cause of the pandemic; that this agent, whileoccasionally killing in a few hours, usually produced its lethal effect bypaving the way for a secondary bacterial pneumonia; and that the agent wasoften, though not always, accompanied by Pfeiffer's bacillus. If this agent werenot bacterial, it must be in the category of the filterable viruses.

The highest mortality of the 1918 pandemic was in the age group between 20and 35 years. Susceptibility to the most severe form of the disease seemed toincrease with age until about 35 years, when it fell off sharply. This suggeststhat exposure to the primary agent in 1889 may have increased resistance in 1918and that the two pandemics were caused by the same virus.

Before and after theinfluenza outbreak of 1918, epidemic waves of acute respiratory diseasesoccurred which were clinically indistinguishable from mild cases in thepandemic. However, in these outbreaks, cases were uncomplicated and mortalitywas nil. These epidemics were called influenza of the interpandemic type orsimply epidemic influenza.

Intensive study of epidemic influenza during the past 15years was begun in England where the first successful isolation of a viruscapable of infecting laboratory animals was achieved. Investigators throughoutthe world have contributed to the work, the principal ones being Andrewes inEngland, Francis in the United States, Burnet in Australia, and Smorodintsev inRussia. From these researches, a fairly clear pattern has emerged although thereremain distinct gaps in our understanding of the disease.

Two causative agents have been identified. Influenza A virus,the first to be recognized, gives rise to epidemics which, in the NorthernHemisphere, tend to occur biennially in odd-numbered years in the winter months,with larger outbreaks every fourth year. Recent studies have shown thatinfluenza A is a group of which the various agents are related butimmunologically distinguishable.

²⁰The Medical Department of the United States Army in the World War. Washington: Government Printing Office, 1925, vol. XV, pt. 2, p. 134.

Influenza B virus has appeared less regularly and less explosively and hascaused less severe epidemics. It was first identified in the United States in1940, and retrospective study of sera saved from the 1936 epidemic of influenzafound them to contain antibodies to this virus. Clinically, it cannot bedistinguished from the disease caused by influenza A. Identification may be byisolation of the virus or by demonstrating a rise in titer of antibody to one ofthe two viruses following an attack. However, in some cases of influenza,identification of neither virus can be made. On the other hand, during anepidemic of one type, a significant proportion of sera may later show evidenceof infection by the other type.²¹

Exceptions to the general statement that epidemic influenza tends to be mildmust be noted. For example, in Boston, Mass., in December 1940 and January 1941,66 cases of staphylococcal pneumonia with 21 deaths occurred with coincidentinfection with influenza A in many of these.²²The Commission on Acute Respiratory Diseases recorded an outbreak of typeI pneumococcal infection in Northville, N.Y., related to influenza B infection.²³In a station such as the Army Air Force Technical School at Sioux Falls, S. Dak.,the already constant, rather high incidence of lobar pneumonia rose wheninfluenza appeared.

Active immunity acquired during an attack of influenza appears from clinicaland serological evidence to be of short duration. Complete correlation betweenthe level of serological immunity and susceptibility to the disease is notpossible although the Commission found some evidence that patients withinitially low antibody titer tended to be more severely ill than those with aninitially high titer. Reference will be made later to the first large-scaleattempt at active immunization of Army personnel with artificially cultivatedinfluenza vaccine.²⁴

What light do these studies of influenza throw upon thepandemic of 1918? Slight epidemiological evidence that the pandemics of 1889 and1918 were caused by the same agent and that therefore the interpandemic varietyis immunologically distinct has been mentioned. On the other hand, Shope's workon swine influenza, a persistent disease which first appeared in 1918, hassuggested another hypothesis. The virus of swine influenza is related to, butnot identical with, influenza A virus. If it is in reality a survival in anotherspecies of the 1918 human influenza, then one may suppose that pandemic andinterpandemic influenza are related. These questions may be answered if anotherpandemic appears. Had such an event transpired during World War II, it wouldlikely not have created the disaster of 1918

²¹Lush, D., Stuart-Harris, C. H., and Andrewes, C. H.: The Occurrence of Influenza B in Southern England. Brit. J. Exper. Path. 22: 302-304, December 1941.
²²Finland, M., Peterson, O. L., and Strauss, E.: Staphylococcic Pneumonia Occurring During an Epidemic of Influenza. Arch. Int. Med. 70: 183-205, August 1942.
²³Commission on Acute Respiratory Diseases and the New York State Department of Health: The Relation Between Epidemics of Acute Bacterial Pneumonia and Influenza. Science 102: 561-563, 30 Nov. 1945.
²⁴See footnote 19, p. 9.

because complications and therefore mortality might have been very favorablyaffected by chemotherapy and antibiotic treatment.

For a complete account of the epidemiology of influenza during World War II,the reader is referred to the chapter by Dr. Thomas Francis, Jr., in anothervolume in the history of the Medical Department in World War II.²⁵In the ensuing paragraphs, only the highlights most relevant to the interests ofthe Professional Service Division will be presented.

Experience in the Continental United States

Influenza was epidemic in the winter of 1940-41, but themajor epidemic took place at the end of 1943. It was explosive in character, butnot all parts of the country were simultaneously affected. It is of interestthat evidence of infection with influenza A virus was found in three patients inMay in a station hospital in Michigan, and on 18 November, at the very beginningof the epidemic, the same virus was recovered from two patients also inMichigan.²⁶ Thereafter, during the epidemic,influenza A appeared in various parts of the country. As in other epidemics, ina number of clinically typical cases, no rise in antibody titer to influenza Avirus could be demonstrated, and there were rare cases in which influenza Bvirus appeared to be involved.

The epidemic was fairly widespread, both in the Army andamong civilians, but like other outbreaks of the interpandemic type, the diseasewas of very short duration, rather mild in character, and generallyuncomplicated. Extensive clinical and serological studies were made by theCommission at Fort Bragg.²⁷ Some of theconclusions drawn are as follows: Influenza with typical features-suddenonset, severe malaise, painful eyeballs, flushed face, injected eyes, highfever, and leukopenia-occurred as a clinical entity in only about halfthe serologically proved cases. Moreover, certain cases of undifferentiatedrespiratory disease, prevalent at the time, presented the same characteristics.In the aggregate, there were significant differences between undifferentiatedrespiratory disease and influenza, but individual cases could not bedistinguished clinically.

In some areas, the 1943 influenza epidemic assumed a slightlymore severe character. An example of this occurred at the Army Air ForceTechnical School in Sioux Falls where the first definite case was noted on 22November. Following this, the incidence rose very sharply, the peak beingreached between 29 November and 1 December. Respiratory disease admissions per1,000 per week for the 4 weeks beginning 14 November through the week beginning5 December were: 7.8, 13.7, 99.0, and 19.6, respectively. Altogether, 11.1percent of the school population was affected. Age, length

²⁵See footnote 2 (1), p. 2.
²⁶Salk, J. E., Menke, W. J., and Francis, T., Jr.: Identification of Influenza Type A in the Current Outbreak of Respiratory Disease. J.A.M.A. 124: 93, 8 Jan. 1944.
²⁷Commission on Acute Respiratory Diseases: Studies of the 1943 Epidemic of Influenza A. II. Comparison of the Clinical and Laboratory Characteristics of Influenza A and Undifferentiated Acute Respiratory Disease (ARD). Am. J. Hyg. 48: 263-275, November 1948.

of service, and duration of stay at the post had nodetectable effect upon susceptibility. Clinically, the cases were typical ofinfluenza; throat cultures on 137 patients showed hemolytic streptococci in 17and pneumococci in 7. There was no evidence that the epidemic engendered thespread of beta hemolytic streptococci.

Associated pneumonitis was said to be present in 5.8 percentof the patients. In these cases, onset and symptoms were similar to theuncomplicated ones, but the disease was more severe, the fever higher and ofslightly longer duration (3.2 days average), and there were rales at the basestogether with X-ray changes. There was no associated leukocytosis, andsulfonamides did not shorten the duration of fever. Influenzal pneumonia-whichthis picture most assuredly suggests-has been very uncommonly foundelsewhere. In addition, at Sioux Falls, there was a sharp rise (from 1.5 tonearly 5 per 1,000) in the weekly incidence of lobar pneumonia, the peakcorresponding precisely with that of influenza.

By 1943, the production of a vaccine made with artificiallycultivated influenza virus had been greatly improved, and a quantity ofmaterial containing both the A and B viruses was available for testing duringthe epidemic. Vaccination of man with both the A and B viruses had been shownnot only to stimulate the production of antibodies but also to induceconsiderable immunity against the artificially induced disease.²⁸The active immunity to type A was apparently of shorter duration than to type B,as those vaccinated with the former 4 months before the test were considerablymore susceptible than those vaccinated 2 weeks before. A large-scale trialseemed warranted. By great good fortune, some 6,263 students in the ArmySpecialized Training Program were vaccinated just before the epidemic. Thesubsequent incidence of influenza was significantly less than that in 6,211controls, the ratio being 1:3.2.²⁹

Evidence of influenza B infection was established in localoutbreaks in different parts of the continental United States, in the CanalZone, Alaska, and Hawaii in the spring of 1945. The occurrence of some influenzain the spring was reminiscent of the year 1918, and this led the chairman of theArmy Epidemiological Board to recommend that the entire Army be vaccinated. Theproposal was approved by The Surgeon General, U.S. Army, and was carried out inOctober 1945. From this uncontrolled experiment, two conclusions³⁰could be drawn by comparing disease rates in the Army with those of unvaccinatedU.S. Navy personnel. The first was that mass

²⁸(1) Francis, T., Jr., Salk, J. E., Pearson, H. E., and Brown, P. N.: Protective Effect of Vaccination Against Induced Influenza A. Proc. Soc. Exper. Biol. & Med. 55: 104-105, February 1944. (2) Salk, J. E., Pearson, H. E., Brown, P. N., and Francis, T., Jr.: Protective Effect of Vaccination Against Induced Influenza B. Proc. Soc. Exper. Biol. & Med. 55: 106-107, February 1944.
²⁹Commission on Influenza: A Clinical Evaluation of Vaccination Against Influenza; Preliminary Report. J.A.M.A. 124: 982-985, 1 Apr. 1944.
³⁰(1) Francis, T., Jr., Salk, J. E., and Brace, W. M.: The Protective Effect of Vaccination Against Epidemic Influenza B. J.A.M.A. 131: 275-278, 25 May 1946. (2) Hirst, G. K., Vilches, A., Rogers, O., and Robbins, C. L.: The Effect of Vaccination on the Incidence of Influenza B. Am. J. Hyg. 45: 96-101, January 1947.

vaccination had exerted a definitely protective effect inlowering mortality, and the second, that influenza B was a better immunizingagent than influenza A.

Experience Overseas

European theater

The history of influenza in the U.S. Army in the European theater isextraordinarily interesting in the light of what might have happened. Since1931, epidemics had occurred in England in the odd-numbered years with a largerwave every fourth year. Had this schedule been maintained, a moderate outbreakwould have occurred in January 1943 and a more severe one in January 1945. Theformer would not have been serious as hospital facilities in England were morethan adequate to care for all troops then stationed there. However, in 1945,hospitals were already filled beyond normal capacity. A sharp epidemic at thattime would have been extremely difficult to cope with and its effect upon themilitary situation would have been grave. It is not known why the epidemic didnot occur.

There is seldom a complete explanation of any epidemiological phenomenon. Inthis instance, the events were as follows: The January 1943 epidemic did nottake place; it was delayed 10 months, until November, when a sharp, widespreadepidemic developed. The rhythmic pattern of influenza was thus disturbed. Latein 1944, the senior consultant in infectious diseases, European theater,ventured to predict to the surgeon, United Kingdom Base, that influenza wouldnot occur in 1945. Partly as a result of this point of view, many hospitalizedpatients with trenchfoot were retained for duty in the theater rather than beingboarded home in order to increase the number of available hospital beds. Itrequired some fortitude to make the prediction of a healthy winter from therespiratory standpoint, but, mirabile dictu, precisely this came to pass, andthe U.S. Army went through the most critical period of the winter campaign withan extraordinarily low noneffective rate due to respiratory disease.

Actually, the prediction was based on fairly sound epidemiological andimmunological reasoning. It has been demonstrated that considerable immunity isleft by epidemic influenza and that outbreaks of the interpandemic type occur atleast 2 years apart. The delay in appearance of influenza in 1943 deflected whatwould have been an almost intolerable extra burden in 1945 at a time whenmedical facilities were badly strained.

Observations made by English investigators³¹ on the behavior of theinfluenza viruses may be briefly summarized, as follows: Although no epidemicoccurred in the winter of 1943, a few sporadic cases of influenza showed rise inantibody titer to influenza B. In the spring and summer. a few cases were notedwith influenza A. This is a very unusual time for

³¹Stuart-Harris, C. H., Glover, R. E., and Mills, K. C.: Influenza in Britain, 1942-43. Lancet 2: 790-793, 25 Dec. 1943.

finding evidence of influenza A infection. Then when thewidespread epidemic took place in November, influenza A was incriminated in manysections of the country.³²

Influenza in the U.S. Army paralleled this disease in the British civilianpopulation. The incidence of all respiratory infections in the U.S. Army in theEuropean theater reached a sudden peak in November 1943, with almost as rapid afall to a point somewhat above the preepidemic level, and a subsequent slowerdecline through the winter months. By June, at the time of the invasion, theincidence was extremely low, and it remained low, with much less than theexpected seasonal upturn, through the winter of 1945.

The great bulk of the cases on which this curve is based fall into thecategory called common upper respiratory infection. That the striking peak ofNovember 1943 represents superadded influenza is presumed because of theexplosive character of the epidemic, its clinical features, and serologicalevidence. Tests were not done on a large scale in the Army, but a sufficientnumber of sera from different parts of the country were examined to show thatthe Army experience was quite similar to British civilian experience; that is, amajority showed a rise in titer to influenza A virus.

In the Army, as with civilians in England and elsewhere, all influenzaencountered during World War II was mild and uncomplicated. The patientswere moderately, not severely, prostrated, and the disease was a short one witha febrile course of 2 or 3 days. To all intents and purposes, pneumonia did notoccur. Influenzal pneumonia of the 1918 type was not seen. A reported increasein civilian deaths in England was found by the Ministry of Health to be due toan increased mortality caused by such conditions as congestive heart failure,associated with the general rise in the respiratory disease rate. In the U.S.Army, no deaths were attributed to influenzal pneumonia. A few complications,such as otitis and sinusitis were observed, but they were not conspicuous.

As for the clinical features of the epidemic, the familiarsymptoms were encountered in many cases. However, the writer was more impressedwith the widespread character of the disease than by its uniformity of behavior.As he had observed in other epidemics of influenza, a typical case was hard todefine. For example, at an airbase in East Anglia in November 1943, a largenumber of patients were treated, but many of these had persistent colds caughton their recent transport voyage, and common upper respiratory disease confusedthe picture of sudden outbreak of influenza.

Mediterranean theater

Maj. (later Lt. Col.) Daniel W. Myers, MC, and Capt. (later Lt. Col.) EdwarddeS. Matthews, MC, stated in their report on respiratory diseases

³²Andrewes, C. H., and Glover, R. E.: Influenza "A" Outbreak of October-December, 1943. Lancet 2: 104-105, 22 July 1944.

in the Mediterranean theater: "Influenza was reported11,094 times in MTOUSA, thus apparently making up 5.9 percent of commonrespiratory infections; however, it is doubtful whether true influenza wasencountered in MTOUSA."³³ The authorsmention the fallacy of making the diagnosis solely upon clinical criteria, asthe same symptoms occurred in other diseases, such as sandfly fever, malaria,and hepatitis, prevalent in the theater. There were no reports of geometricincrease in frequency of influenza-like respiratory disease from anyorganization in this theater and incidence of acute common respiratory diseasesremained within expected seasonal range. Because of lack of sufficientindication, influenzal virus studies were not attempted on a large scale. It isnoteworthy, however, that by far the highest peak for the annual rate of commonrespiratory disease (nearly 300) occurred in January 1944 only very slightlyafter the epidemic of influenza A in England and the United States. It seemsunlikely that the Mediterranean theater should have completely escaped sowidespread a visitation, and superadded influenza would be a logical explanationfor the shape of the curve at that time.

Other oversea theaters

Reported admission rates for influenza in theChina-Burma-India theater and the Pacific areas were low throughout the war, andthe curves for common respiratory infection show no peaks suggestive of thesuperadded effect of influenza.

So the history of influenza during World War II stands in happy contrast tothat of World War I. Pandemic influenza did not occur. Owing to the prolongationof the epidemic cycle in the middle of the war, only one important outbreak tookplace and that at a time when it could be handled with ease.

PRIMARY ATYPICAL PNEUMONIA

Introduction

The term "primary atypical pneumonia" would haveevoked polite incomprehension in the average medical practitioner about 20 yearsago, and today it is one of our commonest diagnoses.

Pneumonias were originally classified on an anatomical basis;this was followed by a combined anatomical-clinical approach and, also, by anendeavor to identify them etiologically. These three phases were oftenharmonious. Thus, the common type of pneumonia appearing as a primary diseasewas lobar in distribution; it had well-defined clinical characteristics, and itwas due to the pneumococcus. Therefore, "lobar pneumonia" wasdesignated an anatomical, clinical, and etiological entity. As the identifica-

³³See footnote 16, p. 8.

tion of pneumococcus types became more exact, the qualification "type Ilobar pneumonia" or "type VII lobar pneumonia" was added.

Apart from the disruption of the pattern caused by the 1918 pandemic ofinfluenza, lobar pneumonia had maintained a fairly consistent record for manyyears in the temperate zones as primarily a winter disease with a usualmortality of about 30 percent in cases not specifically treated. It had beensubjected to exhaustive research, and a great deal of knowledge had beenaccumulated as to the mechanisms of recovery and immunity. The biology of thepneumococcus was, perhaps, better understood than that of any othermicro-organism. By 1938, specific therapeutic sera had been produced for morethan 30 types of pneumococcus.

"Bronchopneumonia" was also originally an anatomical term, but theclassification of bronchopneumonias clinically was much less clearly defined.They formed a heterogeneous group. It was known that a number of micro-organismsbesides the pneumococcus could cause pulmonary consolidation of peribronchialdistribution. Most of these pneumonias, however, were secondary; that is, theyoccurred as complications of other diseases or surgical operations and in theaged and debilitated. Primary bronchopneumonias were recognized, but generallyspeaking they were relatively uncommon. Occasionally, the hemolyticstreptococcus gave rise to primary bronchopneumonia, either in sporadic cases orin localized epidemics, when it often followed in the wake of measles orepidemic milkborne sore throat. One type of virus pneumonia, psittacosis, wasrecognized, but was admittedly rare. As for influenzal pneumonia, this, to allintents and purposes, had vanished after the 1918-20 pandemic.

In 1938, two events occurred to change the clinical concept ofpneumonia. In the first place, in England, a chemotherapeutic agent, M. & B.693 or sulfapyridine, was introduced which was highly effective againstpneumococcal infections. Intense interest was manifested in whethersulfapyridine would supplant serum therapy as the treatment of choice in lobarpneumonia and if it would constitute a successful treatment of thebronchopneumonias. At almost the same time, an increasing number of primarypneumonias, apparently not caused by the pneumococcus and quite obviously notsusceptible to chemotherapy, were being observed. A new disease entity wasrapidly suspected.

The principal characteristics of this disease were asfollows: It seemed to have a predilection for young adults; the onset was rathergradual; the pulmonary consolidation was patchy and often showed a migratorytendency; there was no associated leukocytosis (at least in the early stages),and the bacterial flora of the sputum was not different from that found innormals; some patients were gravely ill but after a variable febrile periodcomplete recovery took place, with a very low overall mortality; and such slighthistological material as was available indicated that the process was aninterstitial pneumonitis with a mononuclear type of exudate. Strepto-

coccus viridans was at first thought to be the cause, butthis hypothesis failed to be substantiated. With no evident bacterial etiology,the disease was then presumed to be due to a filterable virus.

But was it a new disease? Hospital clinical records between 1922 and 1935contain infrequent descriptions of single cases exactly corresponding with thedescription just cited. Furthermore, beginning about 1933, occasional notationsin medical literature indicate that some observers were aware of benignbronchopulmonary infiltrations simulating tuberculosis, and localized epidemicsof an influenza-like disease associated with mild pneumonitis had beendescribed. It is likely that both of these conditions were caused by the sameagent or agents of the "new disease." Atypical pneumonias more or lessconforming to the same description were likewise described as occurring duringthe winter of 1917-18.³⁴ The following factors probably caused thedelay until 1938 in general recognition of primary atypical pneumonia: The morenumerous and severe cases observed in that year, the more exact bacteriologicaldiagnosis of the familiar types of pneumonia, and the introduction of the newchemotherapeutic agents.

Most of the increasing number of papers on primary atypical pneumonia duringthe ensuing years were clinical descriptions, but the research work was goingforward. Broadly speaking, it is now generally agreed that atypical pneumonia iscaused by a virus but by far the majority of cases are not due to theidentifiable viral agents, such as psittacosis, ornithosis-lymphogranuloma, andrickettsia. Endeavors to transmit the agent to laboratory animals, or tocultivate it, have been, on the whole, disappointing. The most important studiesof the etiology of primary atypical pneumonia were performed during World War IIby the Commission on Acute Respiratory Diseases under the direction of Dr.Dingle. Briefly, these studies were as follows:

The disease was successfully transmitted from man to man by bacteria-freefiltrates under conditions of quarantine.³⁵ A minority of thoseinoculated developed atypical pneumonia, but others had less severe illnesseswhich might be called bronchitis or common upper respiratory infection. In otherwords, there is evidence that under epidemic conditions the virus may producemany cases of nondescript respiratory infection for each one of frank atypicalpneumonia. Under experimental conditions, the incubation period was not quite solong as the 2 or 3 weeks which had been estimated from epidemiological studiesof the naturally occurring disease.

Two serological reactions which develop during convalescence from atypicalpneumonia in the majority of cases have been discovered. One of

³⁴See footnote 1, p. 1.
³⁵(1) Commission on Acute Respiratory Diseases:Transmission of Primary Atypical Pneumonia to Human Volunteers. J.A.M.A. 127:146-149, 20 Jan. 1945. (2) Commission on Acute Respiratory Diseases: The PresentStatus of the Etiology of Primary Atypical Pneumonia. Bull. New York Acad. Med.21: 235-262, May 1945. (3) Commission on Acute Respiratory Diseases: AnExperimental Attempt to Transmit Primary Atypical Pneumonia in Human Volunteers.J. Clin. Investigation 24: 175-188, March 1945.

these phenomena is the cold hemagglutinin;³⁶theother is the agglutinin for a certain strain of nonhemolytic streptococcus.³⁷These two agglutinins are not identical, and their significance is not clear.There is general agreement that the particular streptococcus in question is notthe cause of the disease.

Experience in the Continental United States

The concept of atypical pneumonia was still a fairly new one in the winter of1941, and while the disease was recognized in most university clinics, it wasnot familiar to the profession as a whole. In the summer of 1941, something inthe nature of a mild epidemic of pneumonia which did not respond to sulfonamidetherapy occurred in southern training camps. At the request of the surgeon,Fourth Corps Area, a small civilian mission ³⁸ was dispatched inOctober to several southern training camps, notably Camp Claiborne, La. Itreached the conclusion that this was an epidemic of atypical pneumonia. TheSurgeon General accepted a recommendation from this mission that a permanentcommission be instituted for the study of the disease, inasmuch as the Armyseemed an ideal milieu for such a study. This commission, established inDecember 1941, continued to work throughout the war, first at Camp Claiborne,and later at Fort Bragg. It conducted intensive clinical and scientificresearches on the subject of atypical pneumonia, as well as other acuterespiratory infections.³⁹ Among many noteworthy accomplishments of the Commissionon Acute Respiratory Diseases were the successful human transmission experiments.⁴⁰

The characteristics of the disease as originally seen at Camp Claiborne werebriefly described by the chief of medical service of the station hospital andtwo of his colleagues.⁴¹ They reported that 262 cases occurred duringa period of 4 months with a camp population of about 27,000. In general,these cases were mild with a short febrile course. A few more severe cases

³⁶(1) Peterson, O. L., Ham, T. H., and Finland, M.: ColdAgglutinins (Autohemagglutinins) in Primary Atypical Pneumonias. Science 97:167, 12 Feb. 1943. (2) Turner, J. C.: Development of Cold Agglutinins inAtypical Pneumonia. Nature, London 151: 419-420, 10 Apr. 1943.
³⁷Thomas, L., Mirick, G. S., Curnen, E. C., Ziegler, J. E., Jr., andHorsfall, F. L., Jr.: Serological Reactions With Indifferent Streptococcus inPrimary Atypical Pneumonia. Science 98: 566-568, 24 Dec. 1943.
³⁸Drs. A. R. Dochez and Y. Kneeland, Jr., of the College ofPhysicians and Surgeons, Columbia University, New York, N.Y., and Dr. Colin M.MacLeod, of the New York University College of Medicine, New York, N.Y., allmembers of the recently created Board for the Investigation and Control ofInfluenza and Other Epidemic Diseases in the Army.
³⁹(1) Dingle, J. H., Abernethy, T. J., Badger, G. F.,Buddingh, G. J., Feller, A. E., Langmuir, A. D., Ruegsegger, J. M., and Wood, W.B., Jr.: Primary Atypical Pneumonia, Etiology Unknown. War Med. 3: 223-248,March 1943. (2) Commission on Acute Respiratory Diseases: Epidemiology ofAtypical Pneumonia and Acute Respiratory Disease at Fort Bragg, North Carolina.Am. J. Pub. Health 34: 335-346, April 1944. (3) Dingle, J. H.,Abernethy, T. J., Badger, G. F., Buddingh, G. J., Feller, A. E., Langmuir, A.D., Ruegsegger, J. M., and Wood, W. B., Jr.: Primary Atypical Pneumonia,Etiology Unknown. (Parts I, II, and III.) Am. J. Hyg. 39: 67-128, January;197-268, March; 269-336, May 1944. (4) Dammin, G. J., and Weller, T.H. (in collaboration with Commission on Acute Respiratory Diseases): Attemptsto Transmit Primary Atypical Pneumonia and Other Respiratory Tract Infections tothe Mongoose. J. Immunol. 50: 107-114, February 1945.
⁴⁰See footnote 35, p. 18.
⁴¹Moore, G. B., Jr., Tannenbaum, A. J., and Smaha, T. G.: AtypicalPneumonia in an Army Camp. War Med. 2: 615-622, July 1942.

were noted, and two patients died, although there was somequestion of the diagnosis in one of them. Men over 28 years old were beingreleased from the Army at this time. Occasionally, the routine predischargeX-ray in these individuals showed areas of infiltration resembling tuberculosiswhich cleared up quite rapidly. This, taken together with the human transmissionexperiments just cited, suggests that there were probably many "walkingcases" of the disease. The rate of 262 cases in 27,000 troops over a periodof 4 months may thus not indicate the true communicability. That it may be quitehigh under special circumstances is indicated by an occasional report. Forexample, on one occasion about 40 percent of the men out of a single companyengaged as "cleanup teams" in a wire operations school contracted thedisease.

Shortly after the Commission began its activities, a changein terminology of the pneumonias was made by The Surgeon General, so thatthenceforward primary atypical pneumonia was reported as such.⁴³Clinical recognition of the disease became increasingly accurate in manyhospitals, although there is reason to believe that the officially reportedincidence was always low. A perusal of the large number of papers submitted toThe Surgeon General to be approved for publication convinces one that theclinical characteristics of the disease were fairly uniform. The student isreferred to the original articles⁴⁴published by the Commission onAcute Respiratory Diseases for the best account of the manifestations andepidemiology of the disease.

The annual incidence of primary atypical pneumonia in Armycamps throughout the war was remarkably constant. The highest admission rate inthe United States (8.95 per annum per 1,000 average strength) occurred in 1943,although the validity of this may be questioned owing to change in diagnosticcriteria. Seasonal variations in admission rates were more marked; with strikingexceptions, rates were usually higher in the winter months. Generally speaking,cases of atypical pneumonia showed an immense numerical preponderance over lobarpneumonia, rates for which were exceedingly low. One report, from Truax ArmyAir Field, Madison, Wis., gives this ratio as approximately 10:1. At ScottField, Belleville, Ill., 738 cases of atypical pneumonia were seen during aperiod when 24 lobar pneumonias and 37 bacterial bronchopneumonias occurred.⁴⁵At Jefferson Barracks, Mo., 1,862 cases of atypical pneumonia weredescribed as contrasted with 62 lobar pneumonias occurring over the same periodof time.⁴⁶ These

⁴²Idstrom, L. G., and Rosenberg, B.: Primary AtypicalPneumonia. Bull. U.S. Army M. Dept. No. 81, pp. 88-92, October 1944.
⁴³Circular Letter No. 19, Office of the Surgeon General, U.S. Army, 2 Mar. 1942.
⁴⁴See footnote 39 (1), (2), and (3), p. 19.
⁴⁵Owen, C. A.: Primary Atypical Pneumonia. An Analysis of 738Cases Occurring During 1942 at Scott Field, Ill. Arch. Int. Med. 73: 217-231, March 1944.
⁴⁶Van Ravenswaay, A. C., Erickson, G. C., Reh, E. P.,Siekierski, J. M., Pottash, R. R., and Gumbiner, B.: Clinical Aspects ofPrimary Atypical Pneumonia: A Study Based on 1,862 Cases Seen at StationHospital, Jefferson Barracks, Missouri, from June 1, 1942 to August 10, 1943.J.A.M.A. 124: 1-6, 1 Jan. 1944.

cases of atypical pneumonia were said to be more severe thanthe average thus far described in the Army. Two deaths resulted. Pleuraleffusions appeared in 9.7 percent of cases; about one-quarter of these werelarge.

Between 1942 and 1945, 110,133 admissions for primary atypical pneumonia werereported in the Army in the United States with 101 deaths as compared to 50,807admissions and 69 deaths overseas. Atypical pneumonia was never of sufficientmagnitude to interfere seriously with the huge training program. On the otherhand, the rather prolonged course of the disease and the lengthy convalescenceoften affected the military career of the individual concerned. Because of therarity of complications and late sequelae, chronic invalidism did not occur.

Experience Overseas

European theater

During the late summer and autumn of 1942, there was a mild epidemic ofatypical pneumonia among U.S. troops in the European theater. The incidence oflobar pneumonia was very low; in one hospital, for example, during one of theautumn months, the chief of medical service reported 3 cases which might becalled typical pneumonia and 70-odd cases which were atypical. As in casesdescribed in the States among military personnel, these cases were milder onthe average than those presented in earlier reports from civilianhospitals. The febrile course was shorter, being perhaps 5 to 7 days instead of10 to 12, and the tendency to relapse, or prolonged migratory pneumonia, wasmuch less pronounced. Moreover, such bizarre manifestations as erythematousskin lesions, liver involvement, pericarditis, and so forth, which had beennoted on rare occasions in civilian outbreaks, were not observed.A true pleuritic pain, so commonly found in lobar pneumonia, is not a feature ofatypical pneumonia. Sterile pleural effusions may occur; when they do, they areusually small and often interlobar. Occasionally, however, they may persist foran appreciable period, and in 1942 when this was so they were conventionallyconsidered highly suggestive of tuberculosis. It waspointed out then that a small effusion need not be regarded as tuberculous,and where there was any evidence of associated pneumonitis, past or present,atypical pneumonia was probably the cause.

In the autumn of 1942, a board composed of an epidemiologist, Lt. Col.(later Col.) John E. Gordon, MC; a clinician, Lt. Col. (later Col.) YaleKneeland, Jr., MC; and a virologist, Maj. (later Col.) Ralph S. Muckenfuss, MC, was appointed to consider thesubject of atypicalpneumonia. The resultsof its deliberations were embodied in a circular letter, which outlined thehistory and clinical features of atypical pneumonia, together with advice as tomanagement. It was pointed out that sulfonamides were ineffective in thisdisease and that, if the diagnosis could be made with reasonable certainty by amature clinician with an adequate laboratory at his disposal, sulfonamides werecontraindicated. Where the diagnosis was in doubt, or

satisfactory laboratory facilities unavailable, sulfonamidesin full dosage were recommended for a brief but definitive therapeutic trial.Attention was drawn to the possibly prolonged residual effects of an attack ofatypical pneumonia and to the need for a considerable rehabilitation before thesoldier returned to duty.

During the winter and summer of 1943, atypicalpneumonia was less conspicuous. The phenomenon of cold hemagglutination wasdescribed and carefully reported in relation to a fairly large series of casesby a medical officer in the European theater almost simultaneously withindependent discovery of the phenomenon in the United States.⁴⁷Rarecases of encephalitis complicating the pulmonary lesions were encountered in thetheater. In one fatal case, histological evidence was found at autopsy.⁴⁸In two others, encephalitis was recognized clinically from symptoms and spinalfluid findings.⁴⁹

Atypical pneumonia was not generally recognized by the bulkof the British medical profession in 1942, although scientificinvestigators were aware that a form of pneumonia, presumably of viral origin,had recently come into prominence in America. Contacts between Britishinvestigators and American medical officers were soon established. ProfessorBedson,⁵⁰ for example, tested serum from several convalescent U.S.soldiers for antibodies to psittacosis virus with negative results. Dr. C. H.Andrewes tested sera for antibodies to influenza virus,similarly with negative results. The possibility that pigeons imported by theU.S. Army Signal Corps might introduce an ornithosis-like disease in humans intothe British Isles seemed remote when it was found that native British birds werealready infected.⁵¹ It seems highly unlikely that atypical pneumoniawas brought into the British Isles de novo by the U.S. Army. In fact, wardrounds in any British Army hospital in the autumn of 1942 convinced onethat the disease in a mild form was present. Stimulated in part by Americaninterest in the disease,⁵² British physicians shortly began torecognize it, and in 1943 an excellent descriptive article⁵³appearedin the Lancet.

In the autumn of 1943, at a second meeting of the Atypical PneumoniaBoard (p. 21), it was recommended that routine cold agglutinin tests beperformed in hospitals, that careful records be kept, that a summary be made ofthe results of the test in a large series of cases, and that informa-

⁴⁷See footnote 36 (1), p. 19.
⁴⁸Perrone, H., and Wright, M.: Fatal Case of Atypical Pneumonia WithEncephalitis. Brit. M.J. 2: 63-65, 17 July 1943.
⁴⁹Hein, G. E.: Primary Atypical Pneumonia. Lancet 1: 431-432, 3 April 1943.
⁵⁰Sir Sam Phillips Bedson, M.D., F.R.C.P., F.R.S., Consulting Advisor inPathology, Ministry of Health.
⁵¹Andrewes, C. H., and Mills, K. C.: Psittacosis (Ornithosis) Virus inEnglish Pigeons. Lancet 1: 292-294, 6 Mar. 1943.
⁵²Brown, J. W., Hein, G. E., Ellman, P., and Joules, H.: Discussion onAtypical Pneumonia. Proc. Roy. Soc. Med. 36: 385-390, June 1943.
⁵³Drew, W. R. M., Samuel, E., and Ball, M.: Primary Atypical Pneumonia.Lancet 1: 761-765, 19 June 1943.

tion be obtained as to the frequency of second attacks. Some data werecollected, but no important conclusions could be drawn.

The annual admission rate in the European theater for primary atypicalpneumonia was 9.23 in 1942, 6.35 in 1943, and only 4.80 in 1944. Apart from thelate summer-autumn peak of 1942, these rates were considerably lower than inthe United States. This may be partly ascribed to the fact that the virus ofatypical pneumonia seems to have been less widespread and virulent in Englandthan in the United States. Seasoning of troops might have played a role also,but one is inclined to doubt that it was very large, since rates in theMediterranean theater, where the troops were also seasoned, were much higherthan at home for the years 1944 and 1945.

An interesting observation was made in the winter of 1945 atthe 7th General Hospital in Dorsetshire, England. Two patients were studied whoshowed extremely high cold agglutinin titers with associated hemolytic crises.One of these episodes followed a definite attack of atypical pneumonia. Thisphenomenon has since been discussed in considerable detail by Finland and hiscoworkers.⁵⁴

Mediterranean theater

Available statistical reports in the Mediterranean theater do not provide areliable indication of the relative frequencies of lobar and atypical pneumoniabefore May 1944. From 1 May 1944 to 31 March 1945, inclusive, 7,142 primarypneumonias were reported, of which 5,684, or approximately 80 percent, wereclassified as atypical pneumonia.⁵⁵ If this percentage holds for the entirehistory of the theater, it would seem that the preponderance of atypicalpneumonias over bacterial pneumonias was less than in some other areas.

The general situation in regard to pneumonia in the Mediterranean theater asreported in 1945 (p. 8) is described in the following paragraph:

The pneumonia rate in the theater remained at comparativelylow levels until January 1944 when a marked increase was noted principally inthe troops based in Italy. This increased incidence was manifested by both BaseSection and Army troops, the peak level for this season occurring in thePeninsular Base Section during April 1944 when the rate was 38.5 per 1,000 perannum. The rate in Italy remained high until July, the incidence in Army fallingmore precipitously and at an earlier date than in the Base. In January 1945 asimilar rise in pneumonia rates began, the rate in March 1945 reaching a levelsubstantially higher than that in the preceding year. Peninsular Base Sectionand Fifth U.S. Army troops participated in the rise, and once more the incidencewas highest in the Base, attaining the surprising level of 82 per 1,000 perannum in the month of March. It is of interest, though an explanation is notoffered, that pneumonia in the Army Air Forces reached its height in February1945 and fell precipitously in March when Fifth U.S. Army and Peninsular Baserates were still ascending. The case fatality rates showed

⁵⁴Finland, M., Peterson, O. L., Allen, H. E., Samper, B. A., and Barnes, M.W.: Cold Agglutinins. I. Occurrence of Cold Isohemagglutinins in VariousConditions. II. Cold Isohemagglutinins in Primary Atypical Pneumonia of UnknownEtiology With a Note on the Occurrence of Hemolytic Anemia in These Cases. J.Clin. Investigation 24: 451-457; 458-473, July 1945.
⁵⁵See footnote 16, p. 8.

a fall rather than a corresponding rise in the years ofgreatest incidence. In 1943, 24 deaths occurred in 1,427 pneumonias, a casefatality rate of 1.68 percent. There were 7,489 pneumonias and 35 deaths in1944, a rate of 0.47 percent. During the first 3 months of 1945, 3,263pneumonias and 6 pneumonia deaths were encountered, a case fatality of 0.18percent. The quoted rates included all pneumonia deaths.

If 80 percent of the pneumonia was atypical its incidence was at times veryhigh.

Clinical descriptions of the disease in the Mediterranean theater weregenerally similar to those published elsewhere. However, several peculiaroutbreaks occurred which excited a good deal of interest and were the subjectof considerable investigation. The report of Myers and Matthews (p. 8)described these in some detail. One took place in an isolation ward of the 24thGeneral Hospital in the Bizerte area, Tunisia, in the winter of 1943-44.Within a 9-day period, over half the patients and ward personnel (13 in all)contracted mild atypical pneumonia. A tentmate of one of the affected aidmen anda substitute aidman also became ill, the latter 6 days after the first contact.The outbreak appeared to have an unusually short incubation period and a highdegree of communicability. Its origin could not be traced.

During the 1944-45 pneumonia season, seven local outbreaks occurred. One, of82 cases in the personnel of one company, arose in Corsica in December 1944, andthe remaining six outbreaks occurred between December and April in separateorganizations in a 5-mile radius of North Central Italy. The Corsican cases wereas follows:

* * * The usual duration of fever was five days, maximum temperature varyingfrom 100? to 105?, and recovery without serious complications ensued in everycase. Diagnosis was established by chest X-ray examination in nearly everyinstance. Two hundred cold agglutination tests were performed by Capt. Joseph H.Swartz, utilizing the sera from the 82 patients and a 2 percent suspension ofwashed human group O erythrocytes. In two cases agglutination was observed witha serum dilution of 1:32. In the remainder agglutination did not occur withserum titer greater than 1:8. There were no circumstances incriminating aninsect vector.

The extremely high attack rate and the negative cold agglutinin tests suggestthat this was not primary atypical pneumonia. The same report gives adescription of four localized, sharp epidemics occurring near Pagliana,Italy, and totaling at least 355 cases. These constitute additional evidenceof the existence in Italy of a specific and different disease entity. One of theinvolved units had an attack rate of 27.7 percent. The diseasecharacteristically had an abrupt onset, with an incubation period apparentlyvarying from 17 to 23 days. Cold agglutinins were not found, and it wassuspected that the etiological agent might have had an insect vector, a mite,which was found in large numbers in the area used by one of the unitsinvolved.

Two more outbreaks, totaling 53 cases, occurred about 10airline miles north-northeast of Pagliana. These cases again differed in certainnoteworthy respects from atypical pneumonia; that is, abruptness of onset, fre-

quent appearance of pleuritic pain, and absence of coldagglutinins. Complement fixation tests performed with lymphogranuloma antigenon both human and pigeon serum (from the area) were negative for psittacosis,as were other serological tests (Weil-Felix, influenza A and B, coldagglutinin). Attempts at virus isolation were also made. Preliminaryobservations suggested that throat washings from acute cases contained afilterable agent which produced fever on guinea pig inoculation and wastransmissible in series. A rickettsial agent was finally isolated from thematerial. Moreover, late followup serological tests on other casesof the disease which developed in troops returning from Italy have shown thatthe condition was, in fact, Q fever. It seems definitely provedthat all the above cases as well as the so-called Balkan grippe occurringamong British paratroopers in Greece were Q fever.⁵⁶

Myers and Matthews noted that true atypical pneumonia inItaly during the winter of 1943-44 took on a rather more severe character thanthey were accustomed to observe in Army practice. There was a large number ofsevere cases, reminiscent of those described in the United States in 1938, withcyanosis, dyspnea, and extensive pulmonary involvement. Someof these ended fatally. Another group showed a protracted coarse,with persistence of pulmonary infiltration beyond the expected period. In onegroup,⁵⁷ 55.8 percent of cases had residualX-ray changes after 3 weeks of illness.

Lt. Col. Tracy B. Mallory, MC, of the 15th Medical GeneralLaboratory, furnished the following description of his findings in the tissuesof nine fatal cases:⁵⁸

Each of the nine cases showed consolidation of more than75 percent of the total lung substance. Microscopic examination disclosedmassive exudation into the alveoli of a protein-rich fluid, almost free offibrin, and containing mononuclear and red cells but few polymorphonuclearleukocytes. Alveolar wall thickening was observed but was minor in degree.In no case was there evidence of necrotizing bronchiolitis or atelectasis,lesions characteristic of the atypical pneumonia seen in troops in thecontinental United States during 1942-43. A serous or purulent effusion wasnot found in any instance.

Four of the nine evidenced other pathological changesunrelated to the pneumonia but of such character and degree as to havecontributed to the fatal issue. One exhibited recent vegetations superimposedon an old rheumatic valvulitis, the second had a fresh myocardial infarction,the third a hemoperitoneum associated with a fractured pelvis, and the fourth afracture of the dorsal spine with paraplegia. Three other cases displayed a well-marked acutemyocarditis which was deemed to be a complication of thepneumonia and which undoubtedly played in important part in the outcome.

Summary

In summary, primary atypical pneumonia was by far the most common varietyof pneumonia in U.S. troops in the European and Mediterranean

⁵⁶Commission on Acute Respiratory Diseases: Outbreaks of a RickettsialDisease Related to Q Fever. Bull. U.S. Army M. Dept. 5 (No. 3): 245-246, March 1946.
⁵⁷Theodos, P. A., and Zwickel, R. E.: Clinical Aspects of PrimaryAtypical Pneumonia. M. Bull. North African Theater Op. 2: 104-109, November1944.
⁵⁸See footnote 16, p. 8.

theaters. Even so, it never became a military medical problem of any realimportance. Rates for Europe were lower than in the continental United States,but in the Mediterranean they were sometimes higher. On the whole, the caseswere mild and recovery tended to be complete, although an average of about 30days per patient were lost to duty. Very rarely, the individual might be leftwith a chronic bronchitis, sometimes of an asthmatic type. Secondarybronchiectasis was almost unknown. Complications were very infrequent. A few ofthe patients at times seemed to have some secondary bacterial infection. Suchsecondary infections were usually not very clear cut, but when definite theywere controlled by sulfonamides. The death rate was almost nil.

Had the incidence of this condition been higher, it wouldhave been a military problem of some magnitude owing to the rather prolongeddisability incurred by the individual. This low incidence probably reflects aconsiderable degree of immunity in the general population. The virus, too, maybe one of rather low communicability, and the long incubation period militatesagainst the explosive type of epidemic spread when individuals are temporarilycrowded together, as on transports.

Rates for atypical pneumonia were low throughout the war in the Pacific area.They were also low in the China-Burma-India theater apart from a moderate peakin July and August 1942. In the latter area, the disease picture was stated toconform with that seen in the United States except that an initial shaking chilland pleuritic pain were more commonly encountered.

An interesting outbreak, latein 1944, was described by the surgeon of an airbase in India. Fourteen persons,all of whom had been in the same hold of a troop transport arriving in Bombay,came down with atypical pneumonia almost simultaneously a few days afterward.About a fortnight later, there were eight secondary cases at the station.

BACTERIAL PNEUMONIA

Introduction

Lobar pneumonia due to the pneumococcus has been so closelystudied and so accurately described that it would be presumptuous to review thedisease here. Medical records indicate a total of 109,882 admissions for pneumonia other than atypical as occurring in the Army from 1942-45 (table 2). Ofthese, 970 patients died, giving a case fatality rate of 0.88 percent. This isin contrast to a figure of 160,940 admissions for atypical pneumonia with 198deaths. How many of these reported cases were actually pneumococcal pneumonia isimpossible to state; probably the percentage was a relatively small one. Twogeneralizations may be made concerning the condition in World War II. First, theincidence was generally lower than anticipated, particularly overseas. This lowrate was simultaneously true of the civilian population and probably reflects aninexplicable fluctuation in the character

of the disease which had begun some years before World WarII. Secondly, and perhaps for the same reason, the individual cases seemedsurprisingly mild. One is accustomed to think of lobar pneumonia beginningviolently in the classical way, with a rapid development of the complete pictureof the disease and bacteremia in about 25 percent of the cases. In the Army, thedisease did begin suddenly with the customary symptoms, but the patient usuallydid not appear as ill as one might expect; the amount of consolidation by X-raywas often astonishingly slight, and bacteremia was extremely uncommon. It ispossible that these differences were apparent rather than real, that they weredue to prompt recognition and early treatment. Nevertheless, it is the writer'sbelief that the essential severity of the disease was diminished.

Other varieties of primary bacterial pneumonia were rarelyencountered. On the extremely infrequent occasions in which organisms, such as Staphylococcus,Friedl?nder's bacillus, and H. influenzae, produced pneumonia, theyran true to form. Secondary pneumonias, usually on the surgical wards, wereoccasionally noted, but on the whole the control of these conditions byantibiotics was satisfactory.

TABLE 2.-Admissions for primary atypical pneumonia, bacterial pneumonia, and other pneumonia, in the U.S. Army, by area and year, 1942-45

[Preliminary data based on sample tabulations of individual medical records]
[Rate expressed as number of admissions per annum per 1,000 average strength]

Disease category and year	Total Army		United States		Overseas
Disease category and year	Number	Rate	Number	Rate	Number	Rate
Primary atypical pneumonia:
1942-45	160,940	6.32	110,133	7.47	50,807	4.73
1942	19,891	6.13	17,902	6.74	1,989	3.40
1943	51,177	7.45	46,375	8.95	4,802	2.84
1944	43,022	5.52	25,056	6.31	17,966	4.70
1945	46,850	6.18	20,800	7.09	26,050	5.61
Other pneumonia:
1942-45	109,882	4.31	81,962	5.56	27,920	2.60
1942	27,583	8.51	24,267	9.13	3,316	5.66
1943	41,161	5.99	35,735	6.90	5,426	3.21
1944	23,473	3.01	14,470	3.64	9,003	2.36
1945	17,665	2.33	7,490	2.55	10,175	2.19
Bacterial pneumonia:¹
1942-45	50,943	2.00	37,406	2.54	13,537	1.26
1942	10,441	3.22	9,340	3.52	1,101	1.88
1943	16,838	2.45	14,690	2.83	2,148	1.27
1944	13,014	1.67	8,526	2.15	4,488	1.18
1945	10,650	1.41	4,850	1.65	5,800	1.25

¹Cases recorded as lobar pneumonia.

The hemolytic streptococcus gives rise to an occasional caseof primary pneumonia; however, the cases become numerically important only whenfor some reason the organism is widely distributed in a highly pathogenic state,as is sometimes found in association with a milkborne epidemic. Measles andinfluenza viruses seemed to "activate" the hemolytic streptococcus inthe First World War but during the Second World War measles was unimportant inthe Army and influenza of the 1918 type did not occur. These facts probably arerelated to the low incidence of streptococcal pneumonia. What effect did thewidespread use of sulfonamides have in preventing the streptococcus from reallygetting under way? This complex subject will be considered elsewhere, togetherwith that extraordinarily interesting phenomenon, the appearance ofsulfonamide-resistant strains of beta hemolytic streptococci.

Experience in the Continental United States

On summary health reports, statistical data in the Army with regard to the pneumonias are unsatisfactory. After March 1942, the pneumonias were reported under three headings: Primary atypical pneumonia; pneumonia, primary; and pneumonia, secondary. The rates for pneumonia, secondary, were generally very low. Our interest here is in the term "pneumonia, primary."

By definition, this should mean any pneumonia arising de novo, or in thecourse of minor upper respiratory infection, which a medical officer considersto be bacterial, not viral, in origin. Presumably, these should be mainlypneumococcal, that is to say, lobar pneumonia. As might be expected, medicalrecords based on the consolidated statistical health report (WD MD Form 86ab)contain an enormous amount of error, resulting from the natural limitations ofthis source of information.

For example, at Camp Lee, Va., between 6 November 1943 and 3 March 1944, 155cases of pneumonia were reported; 147 designated pneumonia, primary, and 8atypical pneumonia. This seemed of sufficient interest to warrant furtherinvestigation. The Director, Commission on Pneumonia, Army EpidemiologicalBoard, visited Camp Lee and studied records on 97 pneumonia cases admittedsince 1 January 1944. In his opinion, 58 of these were atypical pneumonia, andonly 8 were lobar pneumonia. The remainder consisted of 6 definitelystreptococcal cases, 13 doubtful streptococcal cases, 10 probably bacterialpneumonias from which no organism was isolated, and 2 staphylococcal cases.

There were several reasons for this woeful degree ofinaccuracy. One, of course, was the failure of many clinicians to think clearlyalong etiological lines; another was lack of interest and experience on the partof the laboratory; and last, but not least, was the registrar's habit of makingup the statistical health report from the morning report which was usuallycompiled by a nurse. There is, therefore, little to be gained from a discussionof the overall incidence of so-called pneumonia, primary, as reported onperiodic

summary reports. In contrast, considerable information ismade available from the tabulations of final diagnoses from individualmedical records (table 2).

The low incidence and mortality of lobar pneumonia in the Army may beillustrated by two figures which, although not strictly comparable, do give acrude index of affairs. The death rate from lobar pneumonia is given in theofficial history of the First World War as 2.59 per 1,000 per year, or 259 per100,000 per year, for the period 1 April 1917 to 31 December 1919. PreliminaryArmy figures in World War II, 1942-45, give the death rate for the bacterialpneumonia in the United States as less than 2 per 100,000 per year.

Lobar pneumonia was mildly epidemic in the United States at times, but onlyin certain localities. Epidemic conditions never became generalized. The mostconspicuous instances of this were in the Sixth Service Command where the ratesfor pneumonia were significantly higher than in other service commands. Thesehigh rates were entirely contributed by Air Forces personnel, the rate for ArmyService Forces being not dissimilar to that in other regions. Accordingly, thematter was investigated by the consultant in medicine of the Sixth ServiceCommand and the director of the Commission on Pneumonia who reported a numberof interesting figures. For example, rates for common respiratory disease theweek of 20 October 1944 at three airfields were 150, 111, and 83 as compared to55 and 64 in two service camps. Similarly, the pneumonia rates were 32, 41, and55, compared to 7 and 3. These reported pneumonias included both lobar pneumoniaand atypical pneumonia. The exact proportion of the two varieties was hard todetermine. At one field between 1 January and 8 December 1944, 215 cases ofprimary pneumonia were reported as against 396 atypical pneumonia cases, butwhen the investigators studied the individual medical records rather than thestatistical health report they found that at the three airfields primarypneumonia was being somewhat overdiagnosed at the expense of atypical pneumonia.Nevertheless, it was obvious that lobar pneumonia was unusually prevalent.

At one field, pneumococcus typings had been performed in 160 cases. In these,type VII was present in 18.1 percent of cases, types I and II each in 14.4percent, so that these three together accounted for nearly half the cases. Theprominence of type VII seems a little surprising; whether it was also such anotable offender at the other two fields is unknown.

A careful attempt was made to discover the reasons for this unusual incidenceof respiratory infection including pneumonia. In the final analysis, the moststriking difference between life at the air station and in the service forceswas that the former involved men being together in classrooms all day.

Another interesting example of the behavior of lobar pneumonia was reportedat the Army Air Force Technical School, Sioux Falls. Coincident

with the peak of a sharp epidemic of influenza in November1943, and extending for about a fortnight afterward while the influenza wasrapidly subsiding, the rate for lobar pneumonia (already rather high) rose to anunprecedented level. For the week of 3 December, it was 4.8 per 1,000. In 72cases, pneumococci were isolated and typed. Of these, 17 proved to be type II, 9type V, 6 type I, and 5 type VII. The rest were scattered or untypable. Later inthe winter, during a controlled experiment on sulfadiazine prophylaxis at thesame station, it was noted that the drug appeared to reduce significantly theincidence of lobar pneumonia, although the result was not as striking as in thecase of streptococcal infections.

In harmony with all experience elsewhere, the treatment of lobar pneumoniawith sulfadiazine was highly satisfactory, and complications were veryinfrequent. In this connection, it is interesting to review the role of serumtherapy. At a conference on pneumonia held at the Office of the Surgeon Generalin January 1944, the subject of classification was discussed at length. Therapywas also considered, and it was agreed that antipneumococcus serum may belifesaving in cases of drug-resistant pneumonia. Shortly thereafter, aremarkable variation in the actual use of antipneumococcus serum in varioushospitals was uncovered in a survey by the Professional Service Division. A goodmany hospitals had never used serum while in others it had been employedsurprisingly often. The opinion of all the service command consultants inmedicine was then sought. The great majority agreed that serum was necessary inonly very exceptional instances and that it could, if necessary, be obtainedfrom local sources. In other words, the consensus was that antipneumococcusserum could be discontinued in the Army drug lists; in this, the ChiefConsultant in Medicine, Office of the Surgeon General, and the National ResearchCouncil concurred on 15 May 1944. The advent of penicillin as an addition tosulfonamides had much to do with influencing this view, which would have beenconsidered mildly revolutionary a few years earlier. The efficacy of treatmentof lobar pneumonia with sulfonamides alone is shown by a report of 454 casesover a period of 3 years with only 4 deaths.⁵⁹ In the last year ofthis study, 92 cases were treated without a single death.

An important study of immunization against lobar pneumonia byinjection of specific capsular polysaccharides was started in September 1944 atthe Sioux Falls Army Air Force Technical School⁶⁰where thepneumonia rate had been very high; over 1,500 cases had occurred in thepreceding 2 years. Of these, 34.9 percent were due to type II pneumococcus. Morethan 8,000 men were injected with a single dose of a mixture containingpolysaccharides derived from pneumococcus types I, II, V, and VII with a strik-

⁵⁹Adamson, W. B.: Lobar Pneumonia. Air Surgeon's Bull. (No.11) 1: 21, November 1944.
⁶⁰MacLeod, C. M., Hodges, R. G., Heidelberger, M., andBernhard, W. G.: Prevention of Pneumococcal Pneumonia by Immunization WithSpecific Capsular Polysaccharides. J. Exper. Med. 82: 445-465, December 1945.

ing subsequent immunity to pneumonia caused by these types ascompared with a similar control group. The carrier rate of these four types wasalso significantly reduced, but no effect was noted against infection with, orthe carrier rate of, other types.

Hemolytic streptococcal pneumonia was comparatively uncommon. Some cases wereseen, however, which conformed to the pattern set in the First World War; thatis, an abrupt onset of the pneumonia with symptoms of pleurisy and the rapiddevelopment of a massive effusion. Such effusions were characteristically thinbut, of course, infected. The opportunity to use local penicillin therapy wasseized, but the cases were not sufficiently numerous to draw any finalconclusions as to its efficacy. Early in 1944, one station hospital in the ThirdService Command reported 5 such cases, together with 10 other pneumonias,believed to be streptococcal, which did not have associated empyema. At aboutthe same time, six cases were present in another hospital in the same servicecommand. These numbers, however, were quite unusual. Other varieties ofbacterial pneumonia were occasionally encountered, but not with sufficientfrequency to merit particular comment.

Bacterial pneumonia never became a serious problem in theUnited States, and its response to sulfonamides and antibiotics completelychanged its significance as compared with the First World War.

Experience Overseas

European theater

The incidence of bacterial pneumonia in the European theater was extremelylow, and the mortality almost nil. This small fatality rate can be ascribed, inpart at least, to early diagnosis and satisfactory response to treatment.

Empyema following lobar pneumonia was very inconspicuous in the Second WorldWar. When it occurred, it was ordinarily the result of delay in the institutionof treatment, the pneumonia at times having been unsuspected. Othercomplications were exceedingly rare.

The typing of pneumococci was always difficult overseas. This was no doubt inpart due to lack of training of laboratory technicians. However, it alsoappeared to be a fact that the available typing serum was weak.

There were a number of scattered cases of bronchopneumonia inthe European theater, particularly in the spring of 1944, in which thedifferential diagnosis between atypical and bacterial infection was in doubt.Clinically, these cases resembled atypical pneumonia, but the sputum was morepurulent than one expects in that disease and contained a pathogenic organism.These cases occasionally showed a moderate, although not a dramatic, response tosulfonamides. They may have represented instances of secondary infectionsuperimposed on a pneumonia originally of viral origin.

Mediterranean theater

Preliminary data on pneumonia in the Mediterranean theaterindicate that there were 17,715 admissions for these diseases during the period1942-45. Of these, 12,908 were reported as primary atypical pneumonia, and 2,443(approximately 14 percent) were regarded as bacterial pneumonia. There were 74deaths, and of these, 28 were due to bacterial pneumonia. Presumably, the bulkof the bacterial pneumonias were pneumococcal, and pneumococcal lobar pneumoniais estimated to have caused about one-third of the deaths from pneumonia thatoccurred in the theater.

Other types of bacterial pneumonia were occasionally noted inthe Mediterranean theater but in insufficient numbers to warrant discussion. Asmall number of cases in which a green streptococcus was cultivated from bloodand sputum are recorded. Str. viridans pneumonia was a clinical rarity,but had been previously observed. It is possible to speculate on the relation ofthis condition to atypical pneumonia, with the streptococcus in the role ofsecondary invader, but no proof of such relationship exists.

The standard treatment of lobar pneumonia was sulfadiazine,which yielded satisfactory results. Penicillin was tried in a limited number ofcases and found to be effective. Occasionally, in a severe case, both agentswere used. Serum therapy was only recommended in very exceptional cases.

MEASLES

Introduction

Measles (rubeola) is a highly communicable virus disease witha stereotyped clinical pattern which is universally familiar. Susceptibility tomeasles is considered to be almost universal, and one attack, in the majority ofpersons, confers lifelong immunity. In urban communities, it is more or lessepidemic in the early spring of each year with a greater number of cases inalternate years. Approximately 102,000 cases of measles occurred in the U.S.Army in the First World War, with 2,370 deaths. Associated infections were a cause of serious illness, prolonged invalidism, and death. In World War II,by contrast, the total number of cases was 60,809, with only 33 deaths, in spiteof the fact that the Army was about four times as large and the duration of thewar twice as long. The seasonal peak for measles during World War II occurred inlate winter or early spring, but during World War I peak incidence due tomobilization occurred in the late fall of 1917. This is of sufficient importanceto warrant considerable discussion.

Uncomplicated measles is almost never fatal. The gravity of thecondition lies in complications caused by certain micro-organisms. Bacterialinfections due to pneumococcus, C. diphtheriae, H. influenzae,Mycobacterium tuberculosis, and most particularly the hemolyticstreptococcus, are described.

The most frequent and serious complications ofmeasles are pneumonia and otitis media. In the First World War, there were93,629 admissions due

to measles among enlisted men in the continental United States and Europe ofwhich bronchopneumonia and lobar pneumonia were complications of measles in6,283 cases, with 2,186 deaths. Similar data for the entire Army are notavailable. Suppurative pleurisy, undoubtedly secondary to pneumonia, occurred in645 cases with 268 deaths. There were 3,926 instances of otitis media, but only122 of these patients died. Careful studies of thebacteriology of these complications indicated that the hemolytic streptococcuswas the causative agent in nearly every case. One may ask how this secondaryinfection comes about. Does it occur in a carrier of streptococcus who becomesinfected with measles? Does one catch the streptococcus along with the virus ofmeasles or does one become secondarily infected as a result of living in ahighly contaminated environment after contracting the measles? It seems likelythat all these mechanisms play a part. At one hospital in the First World War,for instance, the carrier rate for hemolytic streptococcus rose steadily onmeasles wards from 11 percent on admission to 57 percent in patients who hadbeen on the ward from 8 to 16 days. If noncarriers of streptococcus with measleswere carefully segregated from carriers at the time of admission, the differencein complications was striking, the rate being 6.4 percent in the noncarriers asopposed to 36.8 percent in the carriers. While the mechanism of secondaryinfection might not always be clear in the individual case, it is safe toconclude that, during a measles epidemic in a training camp, the hemolyticstreptococcus became widely distributed.

Following a measles epidemic with much complicating pneumonia, primarystreptococcal pneumonia made its appearance in some camps. The caseswere severe, with a high incidence of early suppurative pleurisy, and a highcase fatality rate. This disease also spread to the civilian population. Itseems likely that rapid passage from individual to individual through themediation of measles enhanced the essential infectivity and virulence of thehemolytic streptococcus.

Epidemiological studies of measles in the First World War also have aninteresting bearing on more recent events. In such a station as Camp Pike,Ark., which drew its recruits from the rural regions of Alabama, Arkansas,Louisiana, Mississippi, and Tennessee, the rate was enormously higher than incamps drawing from urban areas. Thus, the admission rate for measles among whiteenlisted men at Camp Pike was 164.67 per 1,000 per year, compared to 7.27 atCamp Dix, N.J. For white and colored enlisted men combined, the admission rateswere 142.05 per 1,000 per year for Camp Pike and 7.73 for Camp Dix. Moreover,as might be expected, the incidence of measles was highest in recruits less than2 months in camp. Thus, it was essentially a disease of country boys coming forthe first time in their lives into a densely crowded environment.

The only tenable explanation of the much lower rates formeasles in the Second World War is that the number of susceptibles was muchsmaller. There is no question that a great change in habits of life occurred inrural

America between the two World Wars. In 1910, rural districtswere fairly well isolated; it was the "horse and buggy era"; thefacilities of travel were limited; people stayed on the farm. By 1935, all thishad changed. There was a moving picture house in nearly every village; schoolswere larger, and education was more centralized. As a result, the country boygrowing up in this decade had far more opportunity for exposure to theexanthemata of childhood with a consequent reduction in susceptibility rate atthe time of induction into the Army. Although there is no firm statistical basisfor this conclusion, one cannot avoid feeling that it must be correct.

Complications of measles were much less conspicuous in WorldWar II. Undoubtedly, this was related to the low incidence of the disease. Wherecases are sporadic, rather than epidemic, the widespread dissemination ofvirulent streptococci is unlikely to take place. Moreover, the use ofsulfadiazine in cases with threatened or actual complications unquestionablyserved to modify the picture. Part of the small number of deaths were probablydue to secondary infection; some may have occurred as a result simply ofoverwhelming virus infection or complicating encephalitis.

An average of about 13 days was lost to duty for each case ofmeasles.

Experience in the Continental United States

Most of the measles in the Army took place in the United States for the reasons just mentioned; that is, that it is essentially a disease of unseasoned troops first entering military life. Actually, 54,388 cases occurred in the United States as contrasted with 6,421 overseas. The largest number and the highest rates were reported in 1943, although in the civilian population the absolute numbers of cases were about the same in 1942, 1943, and 1944. As in the First World War, the disease was seasonal, but the peaks were much lower. In other words, while the total number of cases was considerable, measles never became a really serious military problem.

The relative insignificance of complications is illustrated by a report of400 cases of measles at the Station Hospital, Fort Sill, Okla., in which otitismedia occurred but 6 times.⁶¹ Three hundred of these were givensulfonamides, but 100 control cases were untreated. No difference wasnoted in the clinical course of the treated as opposed to the control cases.

Suppression or modification of measles following exposure bythe injection of convalescent serum or immune globulin are establishedprocedures in pediatric practice. Measles in the Army, however, never wassufficiently serious to warrant the generalized use of these measures.Similarly, no attempt was made to apply the principles of active immunization,although interesting preliminary studies, under the direction of the Commissionon Measles

⁶¹Haerem, A. T.: Treatment of Measles and Mumps With Three Well-KnownSulfonamides. Mil. Surgeon 92: 306-309, March 1943.

and Mumps, Army Epidemiological Board, indicated the immunizing value ofartificially cultivated measles virus.⁶²

Experience Overseas

Measles rates in the European theater were low, a total of 2,554 cases beingreported. The disease was sporadic, and nothing in the nature of a real epidemicever developed. Clinically, the cases presented no unusual features.Sulfadiazine was administered to most of the patients for several days duringthe acute phase. Only one death was attributed to the disease.

Between 1 January 1943 and 31 March 1945, 612 cases of measles with no deathswere reported in the Mediterranean theater.

MUMPS

Introduction

Of the so-called communicable diseases of childhood, mumps(epidemic parotitis) was the most common in the U.S. Army. There were 103,055cases recorded between 1942-45 compared with approximately 237,000 during theFirst World War, for a much smaller number of men over a shorter period of time.This marked reduction was greater than that for measles, the comparable figuresbeing 60,809 and 102,000, respectively.

No exact explanation of the reason for this is possible, buta plausible hypothesis suggests itself. As has already been pointed out in thesection on measles, a change in the living habits of rural America probablypermitted more exposure in childhood and resulted in fewer susceptibles ofmilitary age. Measles is more highly communicable than mumps; therefore, whenmeasles occurs under conditions of military life, where opportunity for spreadof epidemic disease is excellent, it is likely that a higher percentage of thenonimmunes will contract measles than mumps. Thus, the proportionate decline inthe incidence of the two diseases during the two World Wars might be expected tobe greater in measles, the highly communicable disease, than in mumps, thedisease of lesser communicability.

Complications

Mumps is a specific virus infection with a particular tendency tolocalization in the parotid glands. In the majority of cases, these are the onlyorgans clinically affected. However, a number of other glands and structures areordinarily spoken of as complications, although they are probably betterregarded as additional manifestations of the virus infection. Generally speak-

⁶²(1) Stokes, J., Jr., O'Neil, G. C., Shaffer, M.F., Rake, G., and Maris,E. P.: Studies on Measles. IV. Results Following Inoculation of Children WithEgg-Passage Measles Virus. J. Pediat. 22: 3-18, January 1943. (2) Maris, E.P., Rake, G., Stokes, J., Jr., Shaffer, M. F., and O'Neil, G. C.: Studies onMeasles. V. Results of Chance and Planned Exposure to Unmodified Measles Virusin Children Previously Inoculated With Egg-Passage Measles Virus. J. Pediat. 22:17-19, January 1943.

ing, these complications are troublesome, but notparticularly serious. Mumps is essentially a nonfatal disease, and in the FirstWorld War the only deaths occurred as a result of infrequent secondaryinfections, such as pneumonia. At that time, the case fatality rate where mumpswas the primary cause of admission was 0.08 percent. As there were only fivedeaths from mumps reported for the entire U.S. Army during the Second World War,it can be seen that even the cited low figure was markedly reduced.

Perhaps the most striking of these so-called complications isorchitis which develops as a rule when the parotitis is subsiding. Rarely it issaid to be the only manifestation of mumps. In a recent study of the disease incivilian life, orchitis is stated to occur in 18 percent of cases of mumps, andin about one-sixth of these the condition is bilateral.⁶³ In over 50 percent,some atrophy is said to result, but ensuing sterility is claimed to be rare,probably because the cases are unilateral, and even in bilateral cases withatrophy a sufficient amount of spermatogenic tissue is left intact. The authorsof this paper recommend surgical decompression in severe cases, a procedurewhich was tried at times in the Army during World War II with allegedly goodresults.⁶⁴ It seems likely that comparatively few cases aresufficiently severe to require such an operation. It is reported to causeremarkable relief, however, in patients with very marked swelling, intolerablepain, and high fever.

Pancreatitis may be another complication of mumps. How oftenit occurs is impossible to say. The clinical diagnosis is occasionally made onthe basis of the appearance of upper abdominal pain, nausea, and vomiting duringthe course of mumps. Unfortunately, there would appear to be no means oflaboratory confirmation, for a study at Camp Adair, Oreg.,⁶⁵ showedthat the level of blood diastase was elevated in 73 percent of cases of mumps.Only 15 percent of these had any symptoms of pancreatitis, and it was assumedthat the diastase originated in the affected salivary glands rather than in thepancreas. In any event, pancreatitis is an unpleasant rather than a seriouscomplication.

The virus of mumps can also cause meningoencephalitis which manifests itselfas a rule by headache, some stiffness of the neck, and increased cell count inthe spinal fluid. Although more severe central nervous system manifestationscan occur, this complication is usually a rather mild one of short duration.Complete recovery is the rule.

In World War I, mumps was third in order of importance as acause for noneffectiveness; in World War II, with less than half thenumber of cases, it was obviously less important. However, as the average numberof days lost

⁶³Wesselhoeft, C., and Vose, S. N.: Surgical Treatment of Severe Orchitisin Mumps. New England J. Med. 227: 277-280, 20 Aug. 1942.⁶⁴(1) McGuinness, A. C., and Gall, E. A.: Mumps at Army Camps in1943. War Med. 5: 95-104, February 1944. (2) Nixon, N., and Lewis, D. B.:Mumps Orchitis; Surgical Treatment. Air Surgeon's Bull. 2: 152-154, May 1945.
⁶⁵Zelman, S.: Blood Diastase Values in Mumps and Mumps Pancreatitis. Am.J.M. Sc. 207: 461-464, April 1944.

to duty for each case was about 18 during World War II, itremained one of the major causes of noneffectiveness among the acute infections,being surpassed only by hepatitis, common respiratory diseases, the pneumonias,gonococcal infections, malaria, syphilis, and dermatophytosis. Mumps usuallybegins in the late autumn, and there is a slow development of the epidemicduring the winter and spring. It is not as explosive as measles. On the otherhand, the incidence may rise sharply when a unit with sporadic mumps is closelypacked in together for a long period of time, as happens on a transport on aprotracted sea voyage.⁶⁶

Experience in the Continental United States

As with other so-called childhood communicables, the greatestincidence of mumps occurs in the first months of Army service. Mumps occurred atsome time in all Army camps and, at times, was sufficiently prevalent to becalled epidemic. One such epidemic at Camp McCoy, Wis., was reported in detailby McGuinness and Gall. During a 7-month period, 1,378 cases were treated in thestation hospital. The slow evolution of the epidemic is noteworthy, the peak of194 cases not being reached until the 17th week. One group of soldiers waspredominantly from the rural areas of the South. This group, roughly equal insize to the other group from the industrialized North, contributed 84 percent ofthe cases. Nearly half the companies in the northern group had but one caseeach, whereas in one southern company 19 percent of the men contracted thedisease. Orchitis occurred in slightly over 36 percent of the cases in thisepidemic as compared to 15 percent of some 250 to 300 cases in an epidemic intwo large camps in the Fourth Service Command. This relationship was borne outelsewhere; that is, the larger the epidemic, the higher the incidence ofcomplicating orchitis. Orchidotomies were performed in 83 cases at Camp McCoywith what were described as good results. An attempt to ward off orchitis byenforcing 2 weeks of bed rest was a failure. The complication appeared to be asfrequent as in ambulatory patients. Of the entire series of mumps cases,one-third were moderate in degree, and one-third severe. Clinicalmeningoencephalitis was uncommon.

Other interesting observations were made elsewhere in regardto orchitis. For example, no relationship between incidence of this complicationand preceding gonorrhea⁶⁷could be found. Generally speaking,treatment with convalescent serum was found ineffective in preventing orchitis,⁶⁸except in a small series treated with serum drawn from convalescent orchitiscases. Here, there was an apparent reduction in incidence to 4.2 percent from anaverage of about 20 percent.

⁶⁶Dermon, H., and Le Hew, E. W.: A Mumps Epidemic in aSmall Task Force. Am. J.M. Sc. 208: 240-247, August 1944.
⁶⁷See footnote 66.
⁶⁸Bailey, W. H., and Haerem, A. T.: Some Observations on the Efficacy of Convalescent Serumin Mumps. Mil. Surgeon90: 134-139, February 1942.

No advance in treatment of uncomplicated mumps was recorded.At one station hospital in the Third Service Command, atropinizing did notappear to ameliorate symptoms⁶⁹in a small series of cases.

On the whole, it may be stated that, while not infrequently bothersome, mumpsdid not constitute a very serious military problem.

Experience Overseas

As in measles, mumps was more common in the United Statesthan overseas, although the difference was less marked. About nine times as manycases of measles were reported at home as abroad; about four times as many casesof mumps were reported. This difference is presumably due to the lowercommunicability of mumps. The disease tended to be mild in the European theater.It was somewhat more common in Negroes than in white troops. A number ofcomplications, particularly orchitis, was observed, but they did not prove verytroublesome. It was the writer's impression that bed rest had little influenceon the likelihood of development of orchitis.

Routine lumbar punctures were done on a number of consecutivecases of mumps, at the 30th General Hospital,⁷⁰ Nottinghamshire, England, andin about half of them the spinal fluids showed pleocytosis. On the other hand,only 10 percent of the cases showed clinical evidence of meningoencephalitis.This indicates that the central nervous system is affected by the virus muchmore often than was formerly believed but that in most cases the infection isasymptomatic. In this connection, it is worth remarking that a very occasionalcase of mild encephalitis without mumps was seen in an individual from a unit inwhich the disease was epidemic. It was suggested that such cases were actuallymumps meningoencephalitis without parotitis. This may well be true, althoughthere was, of course, no way of verifying the diagnosis.

The question of length of quarantine of patients wasconsidered by the infectious disease board. The board suggested that isolationof the individual case could be terminated as soon as all evidence of swellinghad disappeared and there was no fever or other manifestations. This resulted inconsiderable shortening of hospital stay for the mild cases and, as far as onecould tell, produced no untoward consequences.

From 1 January 1943 to 31 March 1915, inclusive, approximately 1,700 cases ofmumps were reported in the Mediterranean theater.

INFECTIOUS MONONUCLEOSIS

Introduction

Infectious mononucleosis is a fairly common disease which affects malessomewhat more than females and which shows a predilection for people under

⁶⁹Potter, H. W., and Bronstein, L. H.: Some ClinicalCharacteristics of Mumps, and the Effect of Belladonna in Treatment; A StudyMade at the Station Hospital, Fort George G. Meade, Maryland. Ann. Int. Med. 21: 469-474, September 1944.
⁷⁰Kirkland, H. B., and Brown, J. W.: Mumps Complicated by Meningo-encephalitis.ETO Med. Bull. 9: 9-10, September 1943.

30 years old. A survey at Harvard University, Cambridge,Mass., in 1944, indicated that it caused 1.5 percent of all student admissionsto the infirmary.⁷¹ Therefore, one would expect to encounter it quite often in theArmy.

It was frequently recognized in the U.S. Army, but it is probable that thereported incidence is considerably below the actual. Infectious mononucleosispresents itself in a number of clinical forms and is often sufficiently vague incharacter to escape detection unless one is on the alert. The classical formwith sore throat, enlargement of the upper deep cervical lymph glands, palpablespleen, and rather prolonged fever, is easily recognized, either immediately orduring a workup to exclude such conditions as syphilis or Hodgkin's disease. Onthe other hand, it is probable that nearly 20 percent of patients have noabnormal lymph gland enlargement. In some cases, the presenting feature is anulcerative throat infection of the Vincent's type, from which Vincent'sorganisms are obtained. There may be an associated stomatitis. A smallpercentage of patients will have jaundice, which may be confused with infectivehepatitis of the ordinary type. Some cases show a skin eruption which may bepurpuric or resemble German measles. Mumps also may be simulated. Evidence ofmeningoencephalitis is found on rare occasions. Lastly, some of the cases areextremely mild and therefore likely to be dismissed as undifferentiatedrespiratory infection.

In connection with jaundice, a study at the Station Hospital, Boca Raton ArmyAir Field, Fla., is worthy of mention.⁷² Serial liver function testsperformed in 15 consecutive cases of infectious mononucleosis showed someevidence in every case of deranged liver function, although clinical jaundicewas not present in any of the cases. Since World War II, it has becomerecognized that the cephalin flocculation reaction is almost invariably positivein mononucleosis. It has, in fact, become a useful ancillary aid in diagnosis.

The etiological agent of infectious mononucleosis is stillunknown, but is not believed to be any of the several microbes which have beendescribed in the past. It may well be a filterable virus, although transmissionexperiments have usually been unsuccessful. Nor has the mode of transmissionbeen established. It is apparently infectious, and occasional, localizedepidemics with a high incidence have been described. The communicability wouldseem to be usually rather low as many of the cases are sporadic, withouthistory of contact. Moreover, cases are treated on an open ward in mosthospitals, and the disease does not appear to spread under these circumstances.If it is true that infection is widespread but that most of the cases aresubclinical, then the phenomenon of apparent low communicability would beexplained.

Infectious mononucleosis is a benign disease with a mortality that may beconsidered nil, though death may result from conditions complicating the

⁷¹Contratto, A. W.: Infectious Mononucleosis; A Study of 196 Cases. Arch.Int. Med. 73: 449-459, June 1944.
⁷²Cohn, C., and Lidman, B. I.: Hepatitis Without Jaundice in InfectiousMononucleosis. J. Clin. Investigation 25: 145-151, January 1946.

disease, as has been recorded in several reports.⁷³The disease may persist for several weeks and require considerable additionaltime before convalescence is complete. Sixty percent of a series of cases in theArmy spent more than 3 weeks in the hospital.

Experience in the Continental United States

During 1944, it became clear that in certain areas in the Fourth and Eighth Service Commands infectious mononucleosis was being more frequently reported than formerly and was presumably mildly epidemic. An extensive clinical study at a station hospital in the Eighth Service Command reviewed the findings in some 556 cases occurring over a period of about a year.⁷⁴ Several points of interest were noted in this excellent report. The disease was found in more than the anticipated number of Negroes, in whom it was formerely thought to be rare. Skin manifestations occurred in 16 percent of all the cases, a higher figure than has been commonly recorded. In 23 percent of 223 patients on whom cardiograms were taken, some abnormality was noted, usually of the T-waves. Six percent of the patients were jaundiced, but unequivocal meningoencephalitis occurred only once. The authors also noted 14 cases in which there was radiographic evidence of pneumonitis, a complication which has received scanty attention in the literature. The rest of the clinical manifestations conformed to the varied picture which has already been described. The blood counts were typical, and heterophile antibody titers of 1:112 or higher were noted in most of the cases. Very few had titers below 1:56. False-positive Kahn tests were only noted in 8 of 263 cases, and the incidence of other false serological reactions, that is, Weil-Felix, Widal, cold agglutination, was exceedingly low.

In contrast, what was described as an epidemic of 91 cases of infectiousmononucleosis in the Caribbean Defense Command occurred in the autumn of 1944.Of these, 48.7 percent showed an exanthem, and the titer of heterophileantibodies was remarkably low, in the majority being below 1:28. A Weil-Felixreaction of above 1:160 was found in half the cases. Moreover, there werenumerous other transient serological reactions, such as the Kahn, Widal, andcold agglutinin tests, a finding which has been noted in typhus. Histologicalstudies of a few excised glands were made at the U.S. Army Medical Museum,Washington, D.C., and the findings were not typical in all of them. Altogether,there is a strong suspicion that this outbreak may have been rickettsial innature.

In summary, it may be stated that while infectiousmononucleosis was fairly common, it was not a serious medical problem in thecontinental United States. It is estimated from sample tabulations that about21,000

⁷³(1) Bernstein, A.: Infectious Mononucleosis. Medicine 19: 85-159, February1940. (2) Custer, R. P., and Smith, E. B.: Pathology of InfectiousMononucleosis. Blood 3: 830-857, August 1948.
⁷⁴Wechsler, H. F., Rosenblum, A. H., and Sills, C. T.: InfectiousMononucleosis; Report of an Epidemic in an Army Post. Ann. Int. Med. 25: 113,July; 236, August 1946.

cases occurred in the total U.S. Army during the period 1942-45, of whichabout 15,000 were in the continental United States.

Experience Overseas

Sporadic cases of infectious mononucleosis were observed inthe European theater throughout World War II where the case rate was aboutone-half that in the United States. At one time, the disease was mildly epidemicin an area of East Anglia, where a considerable number of cases was reportedamong Army Air Force personnel, and also among the personnel of the 2dEvacuation Hospital. In one of these, a most unusual complication occurred,spontaneous rupture of the spleen. The patient recovered following splenectomy.This epidemic was not of sufficient magnitude significantly to affect militaryoperations.

As might be expected in any disease with such variedmanifestations, very unusual clinical cases were observed. One patient, forinstance, had a severe thrombocytopenic purpura during the acute phase of thedisease.⁷⁵ The writer saw a patient who was nearly exsanguinated owing tohemorrhage from an ulcerative pharyngitis. He recovered following transfusionsand penicillin therapy. This indicates that the associated Vincent's infectionin mononucleosis may be a dangerous complication. No useful purpose is served inmultiplying these remembered clinical curiosities.

RUBELLA

Rubella (German measles) is the mildest of the exanthemata ofchildhood. Unlike the others, it is almost wholly uncomplicated, and themortality rate is usually stated as nil. The disease is highly communicable, butthe symptoms are so trifling and the resulting disability of such short durationthat its only importance is its nuisance value. Clinically, it may cause somedifficulty in differential diagnosis as it can be mistaken for other diseases,such as measles, infectious mononucleosis, drug eruptions, scarlet fever, oreven syphilis.

Although the diagnosis is purely clinical, it seems probablethat German measles in its usual form is recognized with some accuracy byclinicians of wide experience. However, the differential diagnosis between itand measles may be difficult for others less experienced. This point is broughtup because of certain peculiarities in its reported behavior during World WarII. In the first place, unlike measles and mumps, rates were higher than in WorldWar I. This is difficult to explain unless the low rates for the First WorldWar resulted from marked under reporting of a trifling malady. Secondly, sevendeaths were ascribed to German measles, and the average days lost to duty (9)was not much lower than the number lost owing to measles (13 days).

⁷⁵Lloyd, P. C.: Acute Thrombocytopenic Purpura in InfectiousMononucleosis; Report of a Case. Am. J.M. Sc. 207: 620-624, May 1944.

Lastly, there was a striking peak in the incidence of Germanmeasles in 1943, the year of the highest rate for measles. All these factscreate the suspicion that cases of measles were being reported as Germanmeasles. The most important differentiating points are the different modes ofonset of the two diseases, and the exanthem of true measles.

There were 135,830 cases of German measles reported in WorldWar II, of which 125,530 occurred in the United States. If these figures areaccurate, it caused more noneffectiveness than measles. It was aninconsequential malady, of extremely benign character, and presented no clinicalfeatures worthy of discussion. However, the interesting observation made inAustralia during the Second World War that German measles occurring in the first2 months of pregnancy is associated with a high incidence of congenitalmalformations of the newborn⁷⁶was obviously devoid of militarysignificance.

Part II. Chronic Respiratory Diseases

CHRONIC BRONCHITIS

"Chronic bronchitis" is a rather loose diagnosticterm which does not usually indicate a clear-cut pathological or, for thatmatter, clinical entity. One variety is the chronic cough of older men, usuallymore marked in winter. Some of these individuals may have occasional wheezingrales; in others, there are no noteworthy physical signs. X-rays of the chestmay show some exaggeration of the bronchial markings, but often the diagnosis isa presumptive one based on the observation of a chronic cough. As the individualgrows older, he may develop varying degrees of emphysema with its attendanteffects on respiratory physiology. Cigarette smoking and chronic disorders ofthe upper respiratory tract are most assuredly contributing factors to thecondition. Because of the age distribution of Army personnel, this type ofchronic bronchitis was more often seen on the officers wards. In some climates,it tended to get worse. It was the writer's impression, for instance, thatelderly officers coughed more in England than they had at home. Dampness,unheated billets, and excessive smoking undoubtedly contributed to this. It hasalso been remarked that in a tropical climate, such as Panama, soldiers with ahistory of recurrent acute bronchitis tend to develop chronic bronchitis.⁷⁷

The management of these cases was largely a matter ofappraisal. In the author's experience, it was almost always impossible topersuade an officer stationed overseas to stop smoking. If the condition weredeemed

⁷⁶Swan, C., Tostevin, A. L., Moore, B., Mayo, H., and Black, G. H.B.:Congenital Defects in Infants Following Infectious Diseases During Pregnancy,With Special Reference to the Relationship Between German Measles and Cataract,Deaf-Mutism, Heart Disease and Microcephaly, and to Period of Pregnancy in WhichOccurrence of Rubella is Followed by Congenital Abnormalities. M.J. Australia 2: 201-210, 11 Sept. 1943.
⁷⁷Cohen, A. G.: An Early Form of Chronic Bronchitis in Panama. War Med. 5:105-108, February 1944.

incompatible with any kind of duty, the patient was boardedhome. At times, it was possible to effect a change in his working and livingconditions. On the whole, however, there was little in the way of medicaltreatment which could be offered. Diagnosis of chronic bronchitis was sometimesused as a handy means of returning home elderly officers who had outlived theirusefulness in an oversea theater.

A just appraisal of the importance of chronic bronchitis in the Army isdifficult. It never seemed to be a major problem, and yet preliminary data basedon sample tabulations indicate that the disease was responsible for about 34,000admissions during the period 1942-45. Nearly half of these occurred overseas.The figure seems extraordinarily high and, perhaps, indicates that the diagnosiswas freely used to designate any case of chronic cough.

Mustard gas is a recognized cause of chronic bronchitis. Had this or otherirritating inhalants been employed in any of the campaigns, the disease mightwell have become a major problem. During World War II, virtually the onlyindividuals at risk were those engaged in the manufacture of mustard gas. A fewcases were reported.⁷⁸

Asthma-The dividing line between chronic bronchitis and asthma is oftennot very clear cut. In younger individuals, chronic bronchitis isoften of an asthmatic character; that is, it may be really a manifestation ofasthma of the endogenous or intrinsic type. These asthmatic bronchitides tendedto get worse overseas.⁷⁹ Moreover, it is interesting to note that, in oneseries of 28 asthmatics whose initial attack occurred in the Army, in 23 itdeveloped overseas.⁸⁰ This is presumably related to heavy pollination incertain tropical areas. At the same time, intrinsic asthma was aggravated duringthe tropical rainy season.

The management of asthma in the Army is fraught with discouragement. Incivilian practice, one can perform an exhaustive study and, depending upon thefindings, endeavor to modify the external environment or to exert influence onthe patient, by either improving his respiratory disease status or actuallyrendering him less sensitive. None of these is feasible during a militarycampaign, save in very exceptional instances. The clinical management of asthma,apart from symptomatic treatment, consists principally in appraisal. Byobserving the patient over a considerable period of time, the medical officertries to answer the following questions: Is this man capable of full duty? Oflimited duty? Should he be boarded home from an oversea theater or, if at home,separated from the service?

Most medical officers believed that very few asthmatics, no matter how mildtheir disease, were fit for combat duty. Exertion and dust, for in-

⁷⁸Morgenstern, P., Koss, F. R., and Alexander, W. W.:Residual Mustard Gas Bronchitis; Effects of Prolonged Exposure to LowConcentrations of Mustard Gas. Ann. Int. Med. 26: 27-40, January 1947.
⁷⁹See footnote 19, p. 9.
⁸⁰Alford, R. I.: Disposition of Soldiers With Bronchial Asthma. J. Allergy15: 196-202, May 1944.

stance, tended to produce some shortness of breath in theseindividuals even when the asthma did not seem to be clinically active. On theother hand, many such individuals could be retained on a limited duty statuseither overseas or at home. It must be added, however, that this was partlydependent on the man's willingness to serve. Asthma undoubtedly has apsychosomatic aspect, and if a relatively mild asthmatic wished to get himselfsent home from an oversea theater, he usually succeeded in doing so. Mild asthmaoften got worse overseas. Thus, asthma was one of the leading medical causes forreturn to the Zone of Interior. The disposition of asthmatics in the UnitedStates may be indicated by a report of 100 consecutive patients, of whom 71 weredischarged from the service.

BRONCHIECTASIS

In young individuals, bronchiectasis may be a progressive anddisabling disease. The likelihood of such a person being accepted for militaryservice is extremely remote, and it has been stated that bronchiectasis was themost common form of chronic nontuberculous lung disease discovered on inductionexamination. However, bronchiectasis of a milder type, essentially cylindricalrather than saccular, may be discovered in a soldier who has previously been inreasonably good health. The pathogenesis of the condition is somewhat obscure,but the lesions may arise apparently as a result of sinusitis, followingpneumonia, or in older individuals as a consequence of chronic bronchitis.Bronchiectasis by itself does not necessarily produce any physical signs orX-ray changes. It is likely, therefore, that the disease is overlooked onoccasion. Undoubtedly, if more bronchographic studies were performed, it wouldbe more frequently recognized.

Bronchiectasis has been termed the most common chronicpulmonary disease in the U.S. Army.⁸¹ As evidence of this, the authorsreported 95 cases investigated bronchographically, mostly for slowly resolvingpneumonia. Of these, 37 showed frank and 24 minimal bronchiectasis. Nobronchiectasis was found in 34 patients. Two other reports might be cited, bothfrom station hospitals in the Third Service Command: At Fort Belvoir, Va., 33cases were discovered during the course of a year⁸²-14 were said tobe severe, 9 moderate, and 10 minimal. At Fort Eustis, Va., the diagnosis wasmade 40 times over a 15-month period;⁸³9 patients were studiedbecause of chronic cough, and the rest were admitted with a diagnosis ofatypical pneumonia. When resolution failed to occur in 4 to 6 weeks,bronchographic studies revealed the true condition. Only 23 of the entire series

⁸¹Evans, W. A., Jr., and Galinsky, L. J.: The Diagnosis ofBronchiectasis in Young Adults; Prebronchographic Roentgen ManifestationsObserved Among Military Personnel. Am. J. Roentgenol. 51: 537-547, May 1944.
⁸²Thompson, T. E., Jr., Cawley, F. C., and Seltzer, A.: A Study ofBronchiectasis at Station Hospital, Fort Belvoir, Virginia. M. Ann. District ofColumbia 13: 93-97, March 1944.
⁸³Grier, G. S., III: Importance of Bronchography in Cases of UnresolvedPneumonia. Arch. Int. Med. 73: 444-448, June 1944.

gave a long history of chronic cough. These patients did notshow the typical textbook picture of severe bronchiectasis with wasting, foulsputum, clubbed fingers, and so forth. The disease was obviously in a muchmilder, or earlier, stage. The author of this study did not believe that theseslowly resolving pneumonias were primary atypical pneumonia but rather that theywere of the variety long recognized as occurring in conjunction with symptomaticflareups of bronchiectasis. Some internists believe that chronic bronchiectasisis at times a rare sequel of severe atypical pneumonia. For instance, thedisease was believed to follow atypical pneumonia in no less than 17 of 33 casesadmitted during a 9-month period to the Percy Jones General Hospital, BattleCreek, Mich.⁸⁴ However, a review of the case reports given in thispaper leaves serious doubts as to the diagnosis of atypical pneumonia. Flareupsof pneumonitis are a common feature of bronchiectasis, and the differentiationof these from primary atypical pneumonia is extremely difficult. Van Ravenswaayand his associates⁸⁵ stated that bronchiectasis occurred as a sequel toatypical pneumonia at Jefferson Barracks in 11 of 1,862 cases. This question isnot yet entirely settled. On the other hand, dilated bronchi, which laterreverted to normal, have been shown in a few patients convalescing from atypicalpneumonia.⁸⁶ The condition was termed "pseudobronchiectasis."

It is estimated that the disease caused more than 6,000 admissions in theperiod 1942-45, four-fifths of them in the continental United States. When thediagnosis was established, it was ordinarily a cause for separation from theservice.

A certain number of cases were treated surgically during World War II. Forexample, in 1943, 25 lobectomies were performed at Fitzsimons General Hospital,Denver, Colo., with 2 deaths.

LUNG ABSCESS

The possibility that a person with a chronic lung abscess could pass theinduction X-ray and physical examination is so slight that cases of thiscondition observed in the U.S. Army presumably developed in the service. Acutelung abscess is by no means uncommon in civilian practice; such cases follow afairly well recognized clinical pattern, and a considerable percentage, perhapsnearly half, recover spontaneously without surgical drainage. The remainder willbecome chronic if not drained. Acute abscesses of this type coming on de novo,so to speak (in the absence of such predisposing factors as dental extractionand tonsillectomy) were very rarely encountered in the Army. The reason for thisis not entirely clear unless it be the generally low incidence of bacterialpneumonias. Lung abscess

⁸⁴Kay, E. B.: Bronchiectasis Following Atypical Pneumonia. Arch. Int. Med. 75: 89-104,February 1945.
⁸⁵see footnote 46, p. 20.
⁸⁶Blades, B., and Dugan, D. J.: Pseudo Bronchiectasis Following Atypical Pneumonia. Bull. U.S. ArmyM. Dept. No. 70, pp. 60-68, November 1943.

developing after surgical procedures also seemed unexpectedlyrare. It is the writer's impression that many of the lung abscesses seen in theArmy were in battle casualties.

The disease is estimated to have been responsible for about 500 admissions inthe 1942-45 period, with 16 deaths.

SPONTANEOUS PNEUMOTHORAX

The sudden appearance of air in the pleural cavity not due to penetratingwounds of the chest wall or endotracheal trauma is known as spontaneouspneumothorax. It was formerly thought to be related to tuberculosis. Now,however, while it is known that spontaneous pneumothorax may occasionally occuras a complication of frank pulmonary tuberculosis, it is also recognized thatthe great majority of cases take place as a result of rupture of a subpleuralbleb and have no relationship with tuberculosis whatsoever. Interestinglyenough, rupture often takes place quite independently of physical exertion.

In many instances, pneumothorax is a recurrent disease. Recurrences wereformerly thought to be uncommon, but it now seems likely that if more frequentlyrecognized by general practitioners their incidence would rise. For example, areport from the Station Hospital, Seymour Johnson Field, Goldsboro, N.C.,⁸⁷points to a highly suggestive history of one or more previous episodes infive out of seven carefully studied cases.

Spontaneous pneumothorax is most frequently encountered in relatively youngmales and gives rise to characteristic physical signs only if the amount ofescaped air is large enough. Roentgen examination, however, as a rule isunequivocal; and if chest X-rays are routinely taken of individuals giving asuggestive clinical history (there is almost invariably some sudden chest painat the onset followed by varying degrees of dyspnea), the condition should notbe overlooked. Pneumothorax is rarely complete; in probably three-fourths of thecases, the collapse is less than 50 percent, so that the number of cases notdetectable with assurance on physical examination is high. Following spontaneouspneumothorax, fluid may occasionally appear, but these effusions are small.

In the usual course of events, there is a single leakage ofair which will be absorbed in the course of time. On the other hand, there maybe recurrent leakages during the reexpansion period, or the pneumothorax may bepermanent due to an open fistula. Such cases require the attention of thethoracic surgeon. Another clinical variety is the so-called tension pneumothoraxwherein so much air escapes (often aided by a valve effect in the rent pleura)that dangerously high intrathoracic pressures are produced. Fortunately, this isa rare happening, but when it occurs, it may constitute a real medicalemergency. The patient is extremely dyspneic and cyanotic,

⁸⁷Pease, P. P., Steuer, L. G., and Chapman, A.: Spontaneous Pneumothoraxin Soldiers. Bull. U.S. Army M. Dept. No. 82, pp. 102-107, November 1944.

and his gasping respirations only serve to aggravate thesituation. In such instances, the quick release of air by means of a needleplunged through the chest wall is lifesaving. Lastly, the rare phenomenon ofhemopneumothorax might be mentioned. Here, bleeding occurs from the torn pleura,sometimes on a large scale.

There were 3,831 admissions for spontaneous pneumothorax toU.S. Army hospitals between 1942 and 1945. It was about twice as common at homeas overseas. The vast majority of these cases were of the uncomplicated benigntype, and in about 10 percent was the condition a cause for separation frommilitary service. Recurrence was the reason for most of the discharges. Theaverage duration of hospitalization was in the neighborhood of 2 months, so thatneither in terms of man-days lost nor manpower permanently lost did the diseaseconstitute a serious medicomilitary problem. The four deaths attributed to thecondition were presumably due to tension pneumothorax.

In 1944, at the suggestion of the National Research Council,a booklet on spontaneous pneumothorax was prepared for general distribution byDr. James J. Waring.⁸⁸ In this, he advocated conservative therapy,with emphasis on hospitalization, bed rest, and the avoidance of air transport.Dr. Waring also discussed the indications for thoracotomy, chemical pleuritis inthe recurrent cases, and the disadvantages of these procedures. In general, headvised an individualized approach to each case.

PULMONARY FIBROSIS

Diffuse fibrosis of the lungs may follow granulomatousdiseases, such as tuberculosis, fungus infections, sarcoidosis, and berylliumpoisoning. It is also a serious occupational hazard of those exposed to theinhalation of silica dust. The preinduction X-ray screening of U.S. Armypersonnel in World War II made it highly improbable that individuals with anysignificant degree of pulmonary fibrosis would be accepted for military service.Moreover, the conditions leading to its development were not a feature of armylife, so that, apart from a certain amount secondary to chronic pulmonarytuberculosis, it was never a feature of medicomilitary practice. It might beadded that the only generalized fungus infection with a fairly high incidence inthe Army, coccidioidomycosis, is not a recognized cause of diffuse pulmonaryfibrosis.

Peculiar instances of rapidly progressive pulmonary fibrosiswhose etiology is entirely obscure have been recorded in the literature. Notableamong these is the report of Hamman and Rich.⁸⁹ It is of interestthat four

⁸⁸Waring, J. J.: Spontaneous Pneumothorax. Office of Medical Information,Division of Medical Sciences, National Research Council, July 1944.
⁸⁹(1) Hamman, L., and Rich, A. R.: Acute Diffuse Interstitial Fibrosis ofthe Lungs. Bull. Johns Hopkins Hosp. 74: 177-212, March 1944. (2) Eder, H., Hawn,C. V., and Thorn, G. W.: Report of a Case of Acute Interstitial Fibrosis of the Lungs. Bull. JohnsHopkins Hosp. 76: 163-171, April 1945.

cases thought to resemble those described by Hamman and Richwere observed in the U.S. Army in New Guinea in 1944. Of these, one patientfinally recovered while two were evacuated and lost to followup study. One cameto autopsy.

PULMONARY EMPHYSEMA

Chronic pulmonary emphysema was occasionally noted in theU.S. Army in the older age groups, particularly among officers. It was lesscommon than in civilian practice, probably owing to the generally higherstandards of health prevailing in the Army. It was said to be responsible forabout 750 admissions in the period of 1942-45, most of them in the continentalUnited States.

MALIGNANT DISEASE OF THE LUNGS

The incidence of malignant disease generally in the U.S. Armyis very low, owing to the age group involved. Moreover, a survey of 15 millionArmy man-years in the 20- to 40-year age group made in 1944-45 indicated thatthe incidence in this group was lower than among civilians.⁹⁰ Thereason for this difference is not apparent. In any case, cancer occurs withexpected frequency in the older age group, again particularly among officers.

As a measure of the importance of malignant disease of thelungs in military medicine, the following is cited: Bronchogenic carcinoma isestimated to have been recognized 200 times during the period 1942-45. Therewere 91 cases of all forms of malignant diseases of the lungs identified atLetterman General Hospital, San Francisco, Calif., between 1944 and 1950. Thisrepresented almost exactly 1 per 1,000 admissions.⁹¹

⁹⁰Lindsey, D., and Cohart, E. M.: Incidence of Cancer in American Males;15,000,000 Man-Years of Aggregate Experience, United States Army, 1944-45.Cancer 3: 945-959, November 1950.
⁹¹For the surgical aspects of diseases of the chest see Blades, Brian B.,Carter, B. Noland, and DeBakey, Michael E.: Surgical Aspects of Diseases of theChest. In Medical Department, United States Army. Surgery in World War II.Thoracic Surgery. Volume II, ch. XI. [In preparation.]-J. B. C., Jr.

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