In Vietnam, as in Korea and in the Asiatic and Pacific theaters in World War II, the cumulative effect of disease was the greatest drain on the strength of the American combat and support effort. Disease admissions accounted for just over two of every three (69 percent) hospital admissions in Vietnam in the period 1965-69; battle injuries and wounds, in contrast, were, responsible for approximately one of six admissions during this period. (Table 1) But the average hospital stay and thus the time lost from duty resulting from combat injury was considerably longer than that resulting from disease. In 1970, however, as a result of the diminution of the American combat role, disease and nonbattle injury accounted for more than half the man-days lost to the, Army in that theater. (Table 2)

While indicative of the theater's single greatest cause of morbidity, disease rates for Vietnam revealed encouraging trends when compared to rates for previous conflicts. The average annual disease admission rate for Vietnam (351 per 1,000 per year) was approximately one-third of that for the China-Burma-India and Southwest Pacific theaters in World War II (844 per 1,000 per year and 890 per 1,000 per year, respectively), and more than 40 percent less than the rate for the Korean War (611 per 1,000 per year). (See Table 1.) *

One of the most striking achievements of military medicine in Vietnam, was the rapid and effective establishment of a preventive medicine program that blunted the impact of disease on combat operations, In World War II, preventive medicine programs in the Far East did not begin to make inroads upon disease incidence until 1945, a year of transition from war to peace. In Korea the delay was less, but still considerable. In Vietnam, however, effective disease control programs were introduced in 1965, and these were successfully maintained throughout the stress of the troop buildup, (See Table 1.)

In addition to minimizing the incidence of disease in American troops, the medical effort in Vietnam had the ancillary benefit in the, late 1960's

*Rates are expressed as cases per annum per 1,000 average, strength, throughout this chapter.

33

¹⁾ July-December only.

Sources: (1) World War II: Morbidity and Mortality in the United States Army, 1940-1945. Preliminary Tables Based on Periodic Summary Reports, Office of the Surgeon General, US Army. (2) Korea: Korea, A Summary of Medical Experience, July 1950-December 1952. Reprinted from Health of the Army, January, February, and March 1953, Office of the Surgeon General, US Army. (3) Vietnam: Health of the Army, May 1966, May 1967, May 1968, May 1969, May 1970, Office of the Surgeon General, US Army.

of making predictable the parameters of various disease problems at particular points in time. The curves depicting the monthly rates per 1,000 per year of those diseases having greatest impact on military operations reveal that, as the Medical Department effort became established and routinized, the annual rates fell, month by month, very closely together. Thus, the 1968 and 1969 curves for malaria, for example, were almost superimposed upon each other. (Chart 6) Not only was disease being controlled but, if preventive measures were properly implemented, its incidence could be forecast with increasing accuracy, and it therefore became a variable for which the field commander could account in planning combat operations.

34

¹⁾ CRO: Carded for record only.
Source: Health of the Command, report submitted to the Deputy Surgeon General, March 1971.

Concentration upon prevention did not preclude the aggressive development of new treatment regimens for old and known problems. In 1965, the average time lost from duty for a patient ill with Plasmodium vivax malaria was 21 days, and for the Plasmodium falciparum malaria patient, 5 weeks. By 1969, P. vivax patients were being returned to duty in 5 to 8 days, and P. falciparum patients in 17 to 19 days. Similarly, in 1966, average time lost from duty for the patient with infectious hepatitis was 49 days; in 1970, it was 35 days.

Diseases of major military import for which the incidence in Vietnam exceeded the incidence in the Army as a whole include malaria, viral hepatitis, diarrheal diseases, diseases of the skin, FUO (fever of undetermined origin), and venereal disease. Venereal disease in Vietnam was most often gonorrhea or other infections of the urinary canal reported under this rubric on clinical grounds alone. It was treated on an outpatient basis and was not a major cause of lost duty time.

The other diseases can he divided into two rather general groups: those, such as hepatitis, which affected relatively few men but incapacitated them for long periods; and those, like most diarrheal and skin diseases endemic to Vietnam, which incapacitated large numbers of men,

35

Sources: (1) World War II: Medical Department, United States Army. Preventive Medicine in World War II. Volume IV. Communicable Diseases Transmitted Chiefly Through the Respiratory and Alimentary Tracts. Washington: U.S. Government Printing Office, 1958. (2) Korea: Korea, A Summary of Medical Experiences, July 1950- December 1952. Reprinted from Health of the Army, January, February, and March 1953. Office of the Surgeon General United States Army. (3) Vietnam: Health of the Army, May 1966, May 1967, May 1968, May 1969, and May 1970. Office of the Surgeon General, United States Army.

36

but for relatively short periods. Malaria, and especially the drug-resistant P. falciparum strain, widespread and incapacitating for relatively long periods, combined the least desirable features of each of these categories and was consequently the greatest medicomilitary disease problem in Vietnam. (Table 3)

 ¹ CRO: Carded for record only.
Source: Health of the Army, May 1966, May 1967, May 1968, May 1969, May 1970, Office of the Surgeon General, US Army.

Other diseases were of grave concern to the Medical Department because of their widespread presence in the civilian population with the concomitant threat to American troops or because of their relatively exotic nature. In the first of these categories fell such conditions as plague, tuberculosis, cholera, and rabies. In the second were found such disease problems as melioidosis, Japanese B encephalitis, and amebiasis. These diseases, although constantly monitored for preventive purposes, had no material effect on US fighting strength.

Statistics on hospital admissions are not an accurate guide to the extent of high-incidence, short-duration diseases, for often these conditions were treated on an outpatient basis. In 1968, for example, the Ninth Infantry Division surgeon reported that, after 5 days in the rice paddies of the Mekong Delta region, a battalion's strength was at one time reduced as much as a third by skin disease; though, not, fully fit for duty, most of these, men were, treated as outpatients. Similarly, statistics on diarrheal disease are commonly considered to reflect a small but unknown fraction of noneffectiveness caused by that problem.

37

A parallel problem is posed by FUO because of the tendency in the field to report such miscellaneous nonfebrile conditions as headache and backache within this category. One informed observer contends that between one-quarter and one-third of the disease reported as FUO was not in fact febrile illness. Statistics on malaria and infectious hepatitis are firmer because of the more precise nature, of the categories and because of the long-term impact of the disease upon the individual patient, although studies reveal that some malaria has been reported as FUO.

Experience showed that the acclimatization process had a significant effect on the impact of, the high-incidence, short-duration disease problems in Vietnam. Speaking at the 1970 Pacific Command Conference on War Surgery, Brigadier General George J. Hayes, MC, stated:

[t]here is a time reference with respect to diarrheal and upper respiratory disease and fevers of unknown origin. . . . The combination of change, in circadian rhythm, climate, and early acquired diarrhea, most certainly of viral origin, lead to about a six week acclimatization period for the troops. After this time the incidence of such disorders in acclimatized troops decreases to a negligible level.

Because of the 12-month rotation policy, unacclimatized troops continually arriving in Vietnam tended to keep the rates for these diseases high.

Acclimatization was not only a physical problem but a psychological and cultural one as well, as indicated by the substantial rates of neuropsychiatric ineffectiveness in the theater, especially during the latter part of the 1965-70 period. Not all replacements, upon entering Vietnam and being assigned to a, unit, were able to negotiate the period of psychological adjustment successfully, despite the salutary effect of the 1-year rotation policy. In addition, for the individual soldier, adjustment to the, Vietnam environment also involved coming to grips with the use of illicit drugs among his peers. The extent of this problem, the result of which is partially reflected in rising neuropsychiatric rates, is only now being explored.

Malaria.

In Vietnam, the average, annual rate of admission to hospital and quarters for malaria, (26.7 per 1,000 per year) was about one-third of that for the Southwest Pacific theater (70.3 per 1,000 per year) and one-quarter of that for the China-Burma-India theater (101 per 1,000 per year) in World War II. (See Chart 6, Table 1) Vietnam rates, however, were, higher than those for the Korean War (11.2 per 1,000 per year), principally because P. falciparum malaria was encountered infrequently during 1950-53, and because primaquine, having just been

38

introduced into general use, had not yet induced the development of a drug-resistant strain of the parasite.

Over-all rates do not reflect the crippling effect of malaria on American strength at the outset of the Vietnam effort. In December 1965, the over-all Army rate in Vietnam reached a peak of 98.4 per 1,000 per year; during that period, rates, for certain units operating in the Ia Drang valley were as high as 600 per 1,000 per year, and at least two maneuver battalions were rendered ineffective by malaria.

Malaria rates among military personnel in Vietnam were cyclical, reaching their low in February or March and their high in October or November. Rates correlate with climatic conditions, region of operation, and degree of contact with the enemy. (Chart 7) Studies done from 1965 to mid-1967 showed that, in the central highlands, enemy soldiers, provided a reservoir for infection by the malaria parasite, especially the P. falciparum, strain.

The progressive gains of the antimalaria program can be measured by the difference between the peak and bottom monthly rates in each year of the American presence. The smaller the difference, the more effective the program has been in curbing malaria. In 1965, the differ-

Source: Health of the Army, May 1966, May 1967, May 1968, May 1969, and May 1970. Office of the Surgeon General, United States Army.

39

ence between these two rates was 97.1; in 1969, it was 20.7. Success was also indicated by the down trend, since 1967, in the absolute number of malaria cases, and by the low level at which deaths from malaria have been held:

Much of the success in the fight against malaria was the result of the ongoing preventive medicine, program and of findings of Army researchers in the field and the laboratory. Advances also were made in the treatment of the disease once it had been incurred, advances which lowered the relapse rate and returned the soldier to duty more quickly.

In mid-1966, a multiple treatment regimen consisting of quinine, pyrimethamine, and dapsone was instituted for the initial attack of P. falciparum. Before the addition of dapsone to this regimen, relapse rates, averaged 7 to 8 percent; after the change, they were lowered to 2 to 3 percent. Studies done in 1969 and 1970 at the 6th Convalescent Center, however, indicated that, among patients who received this regimen orally, the relapse rate had increased to about 10 percent. For those retreated with quinine orally, the relapse rate was 67 percent; with intravenous quinine, 11 percent. These observations suggest that the P. falciparum malaria parasite acquires substantial resistance to quinine, a phenomenon that demands further study.

Plasmodium vivax malaria was experienced very rarely in American troops until mid-1967. Since then, largely because of breakdowns in malaria discipline, it has become an increasingly large factor in the problem with this disease in Vietnam. P. vivax infection, has been easily treated with a short course of chloroquine followed by primaquine. A further problem with this strain, however, arose with its increasing appearance in the United States in Vietnam returnees, an experience which paralleled that of the American forces in Korea.

In 1965, 62 cases of malaria were treated in Army facilities in the United States. In 1970, 2,222 such cases were treated, and this figure is a minimum, neglecting cases that arose in returnees after separation from the service. Eighty percent of these stateside cases of malaria were of the P. vivax variety. This graphically pointed to a failure in the terminal

40

prophylaxis program, which, as a result, has received further command emphasis during 1970:

Hepatitis

As with malaria, the average annual infectious hepatitis rate in Vietnam (6.9 per 1,000 per year) was lower than comparable rates for World War II (SWPA, 27.1 per 1,000 per year; CBI, 9.8 per 1,000 per year), but unlike malaria, Vietnam rates for infectious hepatitis were also lower than those for Korea (7.9 per 1,000 per year) . (See Table 1; Chart 8). The hepatitis rate in Vietnam reached a peak in August 1968;

Sources: (1) World War II:. Medical Department, United States Army. Preventive Medicine in World War II, Volume IV, Communicable Diseases Transmitted Chiefly Through Respiratory and Alimentary Tracts. Washington: US Government Printing Office, 1958. (2) Korea: Korea, A Summary of Medical Experience, July 1950-December 1952. Reprinted from Health of the Army, January, February, and March 1953. Office of the Surgeon General, United States Army. (3) Vietnam: Health of the Army, May 1966, May 1967, May 1968, May 1969, and May 1970. Office of the Surgeon General, United States Army.

41

Source: Health of the Army, May 1966, May 1967, May 1968, May 1969, and May 1970. Office of the Surgeon General, United States Army.

the low rate for the theater, achieved in July 1965, has not been approached since that time. (Chart 9) Unlike statistics for most other disease entities in Vietnam, hepatitis incidence has not shown a downward and stabilizing trend over a period of time. Largely caused by failures in mess and field sanitation and by consumption of nonpotable water and ice available through the local economy, this disease was most commonly acquired by soldiers in their fourth through ninth month in Vietnam. The incidence of hepatitis co-varied with the occurrence of combat operations and with the degree of troop interaction with the civilian populace. Although no specific treatment was available, most patients recovered completely from viral hepatitis with adequate rest and diet. A study at the 6th Convalescent Center reconfirmed Korean War findings that bed rest was not essential after the patient had recovered from the acute phase of this illness.

Recently, added attention has been paid to the serum hepatitis problem. Its true extent among American soldiers is unknown because it is masked by over-all hepatitis statistics, but those who ran the greatest risk were men receiving multiple transfusions after battle injury, and those injecting illicit drugs intravenously.

Diarrheal Diseases

The incidence of that fraction of diarrheal disease severe enough to require hospitalization or assignment to quarters showed a steady downward trend between 1965 and 1970. In 1965, the average theater-wide annual rate for this type of disease was 69 per 1,000 per year; in 1969, it was 35 per 1,000 per year. Also during this period, the difference

42

between the annual high and low rates was significantly reduced, indicating an improvement in control during periods of peak disease incidence. In 1965, this difference was 55.4; in 1969, it was 18.7.

A comparison with World War II experience gives Vietnam diarrheal disease rates added significance. With respect to the China-Burma-India theater, it was reported that ". . . except for an occasional winter month, monthly rates for diarrheas and dysenteries were never under 100 per 1,000 per year until the fall of 1945." For both the China-Burma-India and Southwest Pacific theaters, average annual rates, when viewed over a period of time, did not reveal a downward trend as did those for Vietnam; furthermore, the Vietnam rate was a fraction of the rates for these areas. (Table 4) Accurate comparisons with the Korean experience cannot be made because of differences in the bases for statistics in the two conflicts.

Incidence of diarrheal disease peaked in May or June, corresponding with the monsoon season, and sometimes reached a secondary peak in October. (Chart 10) Affected most severely were unacclimatized troops and troops under combat conditions. For the latter, disease often stemmed from feces-laden soil being washed into inadequately protected water supplies in the field.

Any one of a host of viral, bacterial, or parasitic agents caused diarrhea in Vietnam; an exact etiology could not be identified in most instances. When specific agents were identified, excellent therapy was readily available. The average hospital stay for a patient with a diarrheal problem was 5½ days.

 Sources: (1) World War II: Morbidity and Mortality in the United States Army, 1940-45. Preliminary Table Based on Periodic Summary Reports, Office of the Surgeon General, US Army. (2) Vietnam : Health of the Army, May 1966, May 1967, May 1968, May 1969, May 1970, Office of the Surgeon General, US Army.

43

Source: Health of the Army, May 1966, May 1967, May 1968, May 1969, and May 1970. Office of the Surgeon General, United States Army.

It is notable that cholera, the most feared of diarrheal diseases, has not been a military problem in Vietnam, though it is endemic in the civilian population. Immunization against typhoid fever, however, has not been so effective; 25 Army cases have occurred in the theater, 13 of these in 1970.

Diseases of the Skin

Rates of incidence of skin disease severe enough to require hospitalization or admission to quarters in Vietnam varied around the 30 per 1,000 per year level until 1968, when the institution of a prophylactic program resulted in a dramatic drop to the 20 per 1,000 per year level. (See Table 3.) Figures for 1970, however, indicate a resurgence of this problem to heights comparable to those of 1965. This rise is, as yet, unexplained.

No adequate statistics exist for the comparison of dermatological problems in Vietnam with those of World War II and Korea. As previously noted, hospital statistics provide minimum figures only in this

44

area of disease; dermatological problems have been severely debilitating in units operating in flooded areas of Vietnam.

The three major skin disease problems in Vietnam have been superficial fungal infection (dermatophytosis), bacterial infection, and immersion foot. Disease is probably due to the interaction of four factors: changes brought about in the resistance of the skin to infection because of prolonged exposure to contaminated water; damage to the skin by trauma and friction generated by wearing boots and socks; presence of the etiological organisms in the watery environment; and increased temperature of the tropical environment. Susceptibility to dermatological diseases increased with time in combat, peaking at the 10th month, although some individuals had inherent immunity. Black troops proved to be less susceptible than white troops.

The keynote in dealing with the militarily important dermatological diseases in Vietnam was prevention. Immersion foot was treated through the use of a drying-out period, and the others through the therapeutic use of griseofulvin-V, broadscope antibiotics, and a variety of topical treatments,

Melioidosis

Melioidosis, one of the more exotic medical problems encountered by US troops in Vietnam, is an infectious disease caused by Pseudomonas pseudomalli, a common bacterium of Southeast Asia that has been cultured from soil, market fruits and vegetables, well water, and surface water. The source of the infection is not fully known, nor has man-to-man transference been observed.

In humans, melioidosis is manifest in one of three ways: by acute lung infection, by overwhelming systemic infection, or by localized abscess. The unfamiliarity of American physicians with this, disease and their concomitant failure to diagnose and treat it properly in all but the most severe cases are shown in the low rate and high fatality incidence in 1966:

Although multiple antibiotics were initially used to treat melioidosis, it has become clear over time that tetracycline alone was the drug of choice. Since 1967, most patients have been treated and returned to duty in Vietnam. Patients evacuated from Vietnam or found to have

45

the disease after departing were referred to Valley Forge General Hospital, Phoenixville, Pa., or Fitzsimons General Hospital, Denver, Colo., both designated by The Surgeon General as melioidosis treatment centers.

Neuropsychiatric Problems

Psychosis and neurosis. Until 1968, the neuropsychiatric disease rate in Vietnam remained roughly stable and parallel with that for the rest of the Army. In that year, however, Army-wide rates began to increase, and rates in Vietnam increased more precipitously than in any other location where substantial numbers of American troops were serving, (Table 5, Chart 11) Rising rates showed increases in all areas of psychiatric illness: psychosis, psychoneurosis, character and behavior disorders, for example.

Source: Health of the Army, May 1966, May 1967, May 1968, May 1969, and May 1970. Office of the Surgeon General, United States Army.

The extent of the problem is evident from several statistical indices, Rates for admission to hospital and quarters for neuropsychiatric cases in Vietnam more than doubled between 1965 (11.7 per 1,000 per year) and 1970 (25.1 per 1,000 per year). (See Table 3.) In terms of estimated man-days lost, neuropsychiatric conditions were the second leading disease problem in the theater in 1970; the 175,510 figure, for that year is more than twice as high as the estimate for 1967 (70,000), reflecting a steady increase over the 1967-70 period. (See Table 2.)

Statistics in this area are not comparable with those for World War II and Korea because of differences in diagnostic standards, and categories but it is notable that, unlike the case for World War II, in Viet-

46

¹ January-September only.
Source: Morbidity Report, RCS MED-78.

47

nam the incidence of neuropsychiatric admissions, did not co-vary with the incidence of combat injury, Rather, neuropsychiatric rates rose despite the diminishing combat role in that country in 1969 and 1970.

Several hypotheses have been offered to explain these rising rates in the Army in general arid in Vietnam in particular. It has been suggested, for example, that increased drug abuse has been reflected in increased rates of psychosis, rates which include toxic (drug-induced) psychosis. For Vietnam, it has also been suggested that identity with another peer group, such as one based upon race, political affiliation, or drug use, at the unit level has threatened the integrity of the squad as the, sole reference point for the soldier in combat. This tendency in turn resulted in rising neuropsychiatric rates among individuals who, presented with alternatives, lack the certainty in the stress of combat that confidence in the squad gave the World War II infantryman. These and other hypotheses are currently under study.

In providing psychiatric support for combat troops, the practice in Vietnam was to offer aid as close to the unit as possible, relying upon the social worker and enlisted clinical specialist, and upon, three basic tools- rest, sedation, and supportive psychotherapy. Guidelines indicated that hospitalization was to be avoided except when the patient was dangerous to himself or others or mentally ill. Hospitalization for simple drunkenness, for sociopathological individuals, or for administrative convenience was forbidden by regulation. This adds significance to the rising statistics cited previously.

Drug abuse. One of the unique problems that faced the Medical Department, in Vietnam was the drug milieu into which the American soldier was immersed, both on and off duty, upon arrival in the theater. The growth of illicit drug use within the Army kept pace with that in the larger society, but the ready availability of marijuana, barbiturates, amphetamines, heroin, opium, and other substances in Vietnam, at a lower price for a less adulterated product than that available in the United States, exacerbated the problem.

Comprehensive statistics are not available, but preliminary work based upon sample surveys of soldiers entering and leaving the combat zone indicates that illegal drug use is widespread, especially among younger, lower ranking enlisted men, and that many individuals started using drugs while in Vietnam. One study, done in 1969 at the Cam Ranh Bay replacement depot by Captain Morris Stanton, MC, reported that, of a population of 994 outgoing enlisted men, 53.2 percent had tried marijuana sometime in their lives, 21.5 percent for the first, time in Vietnam. The same study reported that the use, of opium among the soldiers sampled nearly tripled during their stay in Vietnam, rising front 6.3 percent to 17.4 percent.

48

Growing command awareness, of the, nature and extent of the drug problem in Vietnam, led to a search for a flexible, nonpunitive response that would encourage drug users to seek professional help in solving their problems, thus aiding them and, at the same time, serve the Army's interest in conserving the fighting strength. This search resulted in a two-fold program in Vietnam. At the first level the program, was educational, bringing information about the problem to key commissioned and non-commissioned officers so that they could deal intelligently with it, and provide believable advice about drug abuse to the troops in Vietnam. The latter task was the more difficult because conflicting information available in all sectors of American society about the dangers of marijuana and the, linking of its use with other drug problems led to a state of incredulity among American troops. This credibility gap was partially overcome through the use of ex-addicts in information programs, through the realistic redirection of the efforts of the Armed Forces Radio, and through an attempt to dispense factual data personally through medical channels.

But informational activities were directed at men, who had not yet become deeply involved with drugs. For others less fortunate, the experimental institution of an amnesty program in the 4th Infantry Division in 1968 attracted wide attention as a promising attempt to deal with the problem. The program provided that a soldier who voluntarily presented himself as a drug user to his commanding officer, chaplain, or unit surgeon, would not be punished merely for admitting to the use of drugs, if this use had not previously come to the attention of the command. The drug user who voluntarily sought assistance was aided through limited hospitalization to determine the nature and extent of his addiction; through extensive, psychiatric, and other counseling, including group therapy when possible; and through assignment of a "buddy" to give him positive reinforcement in his effort to give up drugs. During the period of counseling and rehabilitation, the patient, continued, as much as possible, to perform full military duties. The 4th Infantry Division's program was adopted throughout the Army in December 1970.