CHAPTER VI
Diseases
The most important skin disease entities in Vietnam were fungal infections, bacterial infections, and immersion injuries. They caused most of the cutaneous disability in combat units and, with the exception of immersion injuries, were among the leading dermatologic causes of outpatient visits and hospitalization in the entire troop population. Their frequency and severity were directly related to the degree of exposure to heat, humidity, water, wet clothing, and mechanical trauma to the skin, thus accounting for their selectively high incidence in infantry units. Modes of treatment were adequate, but preventive measures were seldom effective.
Secondary in importance were diseases such as miliaria and acne, which, while extremely common, seldom resulted in disability. No effective preventive or treatment measures were known short of removing the affected individual from the tropical climate. Because of its low incidence, severe cystic ('tropical') acne was not a significant military problem.
A few conditions, notably pseudofolliculitis barbae and contact dermatitis caused by the insect repellent DEET (diethyltoluamide), were significant for other reasons, including, in these instances, a social reaction and a previously unrecognized hazard. Other conditions in this category include dyshidrosis, leech infestation, and blister beetle dermatitis.
Hundreds of other dermatoses, both common and rare, occurred among the U.S. troop population in Vietnam, but they had no military significance and therefore are not considered further in this history.
FUNGAL INFECTIONS
Superficial fungal infections were the most common and troublesome of all the dermatologic conditions that occurred among U.S. forces in Vietnam. Hardly anyone escaped some form of mycotic skin infection during his tour of duty in Vietnam, and a large majority of ground combat troops in wet, lowland areas developed extensive inflammatory lesions that led to high rates of disability.1 Neither treatment nor preventive measures
1Allen, Alfred M., Taplin, David, Lowy, James A., and Twigg, Lewis: Skin Infections in Vietnam. Mil. Med. 137: 295-301, August 1972.
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were particularly satisfactory, although the situation was significantly improved over that which prevailed in tropical zones during World War II.2
The infections were not caused by exotic species of fungi but by species of dermatophytes and yeasts common to the United States and other temperate areas of the world-Trichophyton mentagrophytes, Trichophyton rubrum, Epidermophyton floccosum, and Candida albicans.3
The chief offender was a zoophilic strain of T. mentagrophytes.4 This organism produced highly inflammatory lesions that often covered extensive areas of the body surface (fig. 5). Not only did these infections tend to create raw, weeping, itching lesions under the boot and in the groin, but they also frequently were complicated by secondary bacterial (streptococcal) infections. Treatment was effective if the soldier was removed from the environment that contributed to his infection; however, this was seldom practical for more than brief periods. Lesions that had almost healed would flare again to full intensity within 3 or 4 days after reexposure to a hot, wet environment.
Thus, the problems with fungal skin infections in Vietnam were related to their incidence, intensity, and persistence, but not to their innate differences from infections common in the United States.
Dermatophytosis (Ringworm)
History and military significance.-Invasion of the keratinized portions of the skin, nails, or hair by dermatophytic fungi was first related to the disease state known as dermatophytosis in the 19th century. Innumerable studies were made of dermatophytosis with little to show for the effort until the dramatic advent of griseofulvin into clinical medicine in 1958.5 Griseofulvin was found to be active against all species of dermatophyte fungi in vivo and to have almost no serious side effects. Within the space of 1 year, the entire management of an age-old disease was revolutionized. Treatment of 'ringworm' infections was put on a rational, scientific footing and ceased to be an inconvenient, messy, time-consuming ordeal with results that were uneven at best. Ringworm clinics closed for lack of patients. In 1964, a new and highly effective topical agent, tolnaftate, was introduced, which, together with griseofulvin, seemed to spell the end of serious difficulties in the management of ringworm infections of the skin.6
Dermatophyte infections have long been a military problem. Severe
2Blank, Harvey, Taplin, David, and Zaias, Nardo: Cutaneous Trichophyton mentagrophytes Infections in Vietnam. Arch. Dermat. 99: 135-144, February 1969.
3See footnote 1, p. 59.
4See footnote 2.5Blank, Harvey: Antifungal and Other Effects of Griseofulvin. Am. J. Med. 39: 831-838, November 1965.
6Robinson, Harry M., Jr., and Raskin, Joan: Tolnaftate, a Potent Topical Antifungal Agent. Arch. Dermat. 91: 372-376, April 1965.
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tinea pedis (athlete's foot) was commonplace in Army camps for many years and especially made its presence felt under the crowded conditions of training centers in the United States during both World Wars.7 A great deal of effort was expended in investigating this problem during World War II, but the upshot of all the research findings was that most of the recommended measures for preventing spread of infection (such as hypochlorite footbaths and duckboards in shower areas) were probably little better than useless.8 Good foot hygiene, coupled with frequent air drying and powdering of the feet, was shown to be the most effective preventive measure.9
In certain oversea commands during World War II, particularly in the Southwest Pacific Area, superficial fungal infections were such an enormous problem that a prominent civilian dermatologist, Dr. J. Gardner
7Grauer, Franklin H., Helms, Samuel T., and Ingalls, Theodore H.: Skin Infections. In 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, pp. 83-125.
8See footnote 7.
9See footnote 7.
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Hopkins, was dispatched to investigate the situation.10 Dr. Hopkins found that extensive involvement of the skin of the body and the groin (tinea corporis and tinea cruris) was common and occasionally was severe enough to require hospitalization. Little opportunity existed to culture these lesions, but of the 13 positive cultures obtained, 10 yielded T. mentagrophytes.11 This was in sharp contrast to results obtained at Fort Benning, Ga., where T. mentagrophytes was virtually unknown as a cause of tinea corporis or tinea cruris.12
British forces operating in Malaya during the late 1940's and early 1950's encountered the same fungal skin infection problems as did American soldiers in the Southwest Pacific almost a decade previously.13 Severe tinea infections were highly prevalent, especially during the rainy season, and nearly all were caused by a zoophilic strain of T. mentagrophytes.14 A special dermatologic team investigated and concluded that the infections were brought by the men to the Tropics in the form of latent toeweb infections and that activation and spread of infection to other body areas were related to environmental factors, particularly heat and humidity.15 The team also noted that native Asian troops did not suffer from these severe infections and that the few lesions which could be found among them were generally caused by T. rubrum rather than T. mentagrophytes.16
Epidemiology.-The epidemiology of dermatophytosis among U.S. combat forces in Vietnam was quite different than that found in similar populations in the United States.17 The majority of infections were caused by an elastase-producing, zoophilic strain ofT. mentagrophytes (table 15), whereas almost all of the T. mentagrophytes infections in the United States were caused by elastase-negative, anthropophilic strains. Whether the pathogens in Vietnam were derived from an animal host was not definitely determined, but identical-appearing strains of T. mentagrophytes were
10Thiesmeyer, Lincoln R., and Burchard, John E.: Combat Scientists. Boston: Little, Brown and Co., 1947, pp. 138-140.
11Pillsbury, Donald M., and Livingood, Clarence S.: Dermatology. In Medical Department, United States Army. Internal Medicine in World War II. Volume III. Infectious Diseases and General Medicine. Washington: U.S. Government Printing Office, 1968, pp. 543-546.
12Hopkins, J. Gardner, Hillegas, Arthur B., Ledin, R. Bruce, Rebell, Gerbert C., and Camp, Earl: Dermatophytosis at an Infantry Post: Incidence and Characteristics of Infections by Three Species of Fungi. J. Invest. Dermat. 8: 291-316, June 1947.
13(1) Sanderson, P. H., and Sloper, J. C.: Skin Disease in the British Army in S.E. Asia. I: Influence of the Environment on Skin Disease. Brit. J. Dermat. 65: 252-264, July-August 1953. (2) Archer, T. C. R.: Medical Problems of the Operational Infantry Soldier in Malaya. J. Roy. Army M. Corps 104: 1-13, January 1958.
14Sanderson, P. H., and Sloper, J. C.: Skin Disease in the British Army in S.E. Asia. II: Tinea Corporis: Clinical and Pathological Aspects, With Particular Reference to the Relationship Between T. interdigitale and T. mentagrophytes. Brit. J. Dermat, 65: 300-309, September 1953.
15Sanderson, P. H., and Sloper, J. C.: Skin Disease in the British Army in S.E. Asia. III: The Relationship Between Mycotic Infections of the Body and of the Feet. Brit. J. Dermat. 65: 362-372, October 1953.
16See footnote 14.
17Allen, Alfred M., and Taplin, David: Epidemic Trichophyton mentagrophytes Infections in Servicemen: Source of Infection, Role of Environment, Host Factors, and Susceptibility. J.A.M.A. 226: 864-867, 19 Nov. 1973.
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recovered from 29 (23 percent) of 124 wild rats trapped near troop living quarters (fig. 6).
The prevalence and severity of infection were directly related to the degree of exposure to water and wet clothing. The prevalence of clinically diagnosed lesions was approximately twice as great in infantrymen who were frequently exposed to water in paddies and swamps as in support troops who were able to stay dry (table 16). Fungal lesions in infantrymen were extensive and markedly inflamed, whereas those in support troops consisted of small patches on the body or mild rashes in the groin.
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TABLE 15.-Fungal species in culture-positive cases of dermatophytosis in U.S. troops and Vietnamese
Fungal species | U.S. infantrymen, | U.S. support troops, | Vietnamese military and civilians, percent |
Trichophyton mentagrophytes, zoophilic | 73 | 46 | 0 |
T. mentagrophytes, anthropophilic | 1 | 0 | 0 |
Trichophyton rubrum, common | 9 | 13 | 0 |
T. rubrum, "Vietnamese" | 5 | 2 | 95 |
Epidermophyton floccosum | 12 | 39 | 5 |
Source: Allen, Alfred M., and Taplin, David: Epidemic Trichophyton mentagrophytes Infections in Servicemen. J.A.M.A. 226: 864-867, 19 Nov. 1973.
Toeweb infections (tinea pedis) were surprisingly rare, especially among infantrymen whose feet were exposed to water day after day (table 17). This was one of the facts that contradicted the theory that inflammatory tinea corporis was caused by activation and spread of previously latent toeweb infections. Another was that tinea pedis was just as common in men with no signs of tinea corporis as it was in men with this disease, indicating a complete lack of association between clinically apparent tinea pedis and tinea corporis.
Susceptibility to infection was nearly universal among American troops. The highest rates of infection occurred among infantrymen in wet terrain, nearly three-fourths of whom had clinically recognizable infections by the fourth month of tropical service.
The epidemiology of ringworm infections among adult Vietnamese, both military and civilian, stood in marked contrast to that in American soldiers. T. mentagrophytes infections were rare. The predominant pathogen in adult Vietnamese was a distinctive morphologic variant of Trichophyton rubrum (fig. 7, table 15). The prevalence of tinea corporis among Vietnamese infantrymen exposed to wet terrain was similar to that in their American counterparts (table 16), but the frequency of infection in Vietnamese rice farmers was much lower than in the soldiers. Presumably this was because the farmers wore lighter clothing and could dry their skin at night (fig. 8).
Etiology.-Nearly all dermatophyte infections in American servicemen were caused by T. mentagrophytes (zoophilic or anthropophilic strains), T. rubrum, and E. floccosum (table 15). The species distribution varied according to the site of infection; lesions on the exposed skin areas (face, trunk, and extremities) were usually caused by zoophilic T. mentagrophytes, whereas those in the intertriginous areas (groin and toewebs) were commonly caused by T. rubrum and E. floccosum as well as by T. mentagrophytes (table 18).
Environmental factors played an important role in the etiology and pathogenesis of fungal skin infections. The single most important factor
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TABLE 16.-Prevalence of clinically diagnosed tinea corporis and tinea cruris in U.S. troops and Vietnamese, 1968-69
Population | November | December | January | February | ||||||||
Number | Total | Percent | Number | Total | Percent | Number | Total | Percent | Number | Total | Percent | |
U.S. infantrymen | 110 | 188 | 59 | 79 | 157 | 50 | 34 | 73 | 47 | 13 | 68 | 19 |
U.S. support troops | 34 | 103 | 33 | 33 | 120 | 28 | --- | --- | --- | --- | --- | --- |
Vietnamese infantrymen | --- | --- | --- | --- | --- | --- | 28 | 50 | 56 | 15 | 43 | 35 |
Vietnamese civilians | 8 | 81 | 10 | --- | --- | --- | --- | --- | --- | --- | --- | --- |
Source: Allen, Alfred M., and Taplin, David: Epidemic Trichophyton mentagrophytes Infections in Servicemen. J.A.M.A. 226: 864-867, 19 Nov. 1973.
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TABLE 17.-Site-specific prevalence of clinical dermatophytosis in U.S. troops and Vietnamese
Location | U.S. infantrymen, | U.S. support troops, | Vietnamese infantrymen, | Vietnamese civilians, |
Toewebs and soles | 8 | 14 | 0 | 0 |
Feet (dorsa) and ankles | 18 | 3 | 8 | 1 |
Legs | 4 | 1 | 3 | 1 |
Groin | 33 | 22 | 20 | 5 |
Buttocks | 19 | 8 | 25 | 5 |
Waist | 8 | 3 | 23 | 0 |
Above waist | 1 | 1 | 9 | 0 |
Source: Allen, Alfred M., and Taplin, David: Epidemic Trichophyton mentagrophytes Infections in Servicemen. J.A.M.A. 226: 864-867, 19 Nov. 1973.
was occlusion of the skin by water or sweat-dampened clothing. This was indicated by the marked tendency for lesions to occur in areas where opportunities for occlusion were greatest, the groin, buttocks, ankles, and dorsa of the feet in infantrymen, and the groin and toewebs in support
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TABLE 18.-Distribution of dermatophytic pathogens in U.S. troops in the Mekong Delta, 1968-69
Location | Trichophyton | Trichophyton | Epidermophyton | Candida | No pathogen isolated |
Toewebs | 3 | 7 | 2 | 8 | 20 |
Boot/sock | 12 | 1 | 1 | 2 | 4 |
Leg | 2 | 1 | 0 | 0 | 1 |
Groin | 23 | 7 | 24 | 7 | 18 |
Buttocks | 21 | 2 | 0 | 1 | 10 |
Waist | 7 | 0 | 2 | 0 | 8 |
Other | 3 | 0 | 0 | 0 | 3 |
Source: Allen, Alfred M., and Taplin, David: Epidemiology of Dermatophytosis in the Mekong Delta. In Fungous and Bacterial Skin Infections in the Tropics, Annual Progress Report, by Harvey Blank and David Taplin, to the U.S. Army Medical Research and Development Command, March 1970, pp. 14-25.
troops (table 17). The effects of occlusion also were vividly demonstrated by the outline and distribution of the lesions in instances where the source of occlusion (that is, boots and socks, web belt, or scrotum) clearly left its imprint.
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Also of consequence was the host's reaction to dermatophytes. Previous studies had indicated that protective immunity could follow infection with a particular dermatophyte,18 but there was little to suggest that this occurred among troops in Vietnam.19 Nonetheless, the differences in frequency of T. mentagrophytes infections between Americans and Vietnamese suggested that the latter may have been protected by immunity developed in response to infections sustained during childhood (fig. 9).20
The means by which infections were transmitted from person to person or from animals to people was not established. Laundered clothing was repeatedly suggested as an important vehicle for spread of infection,21 but survey data indicated that this was unlikely.22 More probable was that transmission occurred by contact with spore-bearing rafts of desquamated epithelium which had been shed into the environment from infected lesions.23
Clinical features.-The most common form of dermatophytosis was a T. mentagrophytes infection of the glabrous skin.24 Many infections covered
18Huppert, Milton: Immunization Against Superficial Fungous Infection. In Fungi and Fungous Diseases (G. Dalldorf, editor). Springfield: Charles C. Thomas, Inc., 1962, pp. 239-253.
19See footnote 17, p. 62.
20See footnote 17, p. 62.
21See footnote 2, p. 60.
22See footnote 17, p. 62.
23Georg, Lucille K.: Epidemiology of the Dermatophytoses: Sources of Infection, Modes of Transmission, and Epidemicity. Ann. New York Acad. Sc. 89: 69-77, 27 Aug. 1960.
24See footnote 2, p. 60.
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large areas of the body surface. The usual sites of involvement were the groin, buttocks, and feet. Among infantrymen exposed to wet terrain, the infections had a striking predilection for areas covered by layers of clothing, particularly the feet and ankles (but not including the toewebs and soles), the buttocks, the groin, and the waist under the webbed canteen belt (figs. 10-13).25
T. mentagrophytes infections often started as a mycotic folliculitis (fig. 14) and spread to form bright red, ringed lesions which became confluent (fig. 15). In black soldiers, these lesions appeared as areas of hyperpigmentation and psoriasiform scaling rather than as red rashes (figs. 16 and 17). The principal symptom was itching, which often was severe enough to cause loss of sleep at night.
When the surface infections had subsided, multiple pus-filled nodules often remained at the site of hair follicles (figs. 18 and 19). These follicular infections usually persisted for weeks after the surface inflammation had completely disappeared. The pus from these nodules yielded pure cultures of T. mentagrophytes.
Secondary infection of the raw, weeping, inflamed surfaces produced by T. mentagrophytes infections was common. The usual invaders were Streptococcus pyogenes and Staphylococcus aureus.26
T. mentagrophytes infections of the bearded area of the face were not unusual, but they posed considerable diagnostic and management problems for physicians.27 They were frequently misdiagnosed as abscesses, granulomatous processes, or contact dermatitis (fig. 20). As a result, a number of unnecessary attempts were made to drain the pus, and this led to more residual scarring than otherwise would have been the case.
Toeweb infections were essentially no different than those commonly found among troop populations in the southern United States during the summer (figs. 21 and 22).28 They caused mild to moderate itching, but otherwise were not a significant problem.
Diagnosis.-Physical examination alone was sufficient to establish a presumptive diagnosis of dermatophytosis in the majority of cases that occurred in Vietnam. Typical patches and rings in exposed areas of skin, such as on the ankles and buttocks, were difficult to confuse with other dermatoses (figs. 23 and 24).
However, skin lesions in the groin, the toewebs, the axillae, and the bearded area of the face often presented considerable problems in differential diagnosis. In the groin, for example, dermatophytosis was frequently difficult to differentiate from candidiasis, erythrasma, and simple intertrigo on clinical grounds alone, and laboratory aids (for example, cultures) often were necessary to establish the correct diagnosis.
25See footnote 17, p. 62.
26See footnote 17. p. 62.
27See footnote 2, p. 60.
28See footnote 17, p. 62.
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FIGURE 14.-Early mycotic folliculitis caused by T. mentagrophytes.
Microscopes and fungal culture media seldom were available except to dermatologists, and even then their use was limited by constraints of time and feasibility. The vast majority of physicians who were called upon to treat dermatologic disorders had no access to laboratory facilities, and as a result, many diagnostic errors were made.
Prognosis and complications.-The prognosis for resolution and complete healing of dermatophyte infections was heavily dependent on environmental factors. For troops living under field conditions during the rainy season, particularly those with T. mentagrophytes infections, the prognosis was not good. Constant exposure of the skin to water and wet clothing effectively counteracted even the most conscientious attempts at treatment.
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During the dry season, however, when conditions were more favorable, the lesions often underwent spontaneous resolution (table 16).
Inflammatory T. mentagrophytes infections, especially those on the ankles and feet, not infrequently were secondarily infected by beta-hemolytic streptococci (fig. 25), thus leading to further damage to the skin.
With the exception of the scarring that resulted from inappropriate treatment of tinea barbae, adverse long term effects were not observed.
Treatment.-The vast majority of patients with ringworm infections were treated on an outpatient basis with griseofulvin plus a topical agent such as tolnaftate, Whitfield's ointment, or Castellani's solution. The usual dose of griseofulvin was 1 gram per day. Survey data indicated that few soldiers took this medication for the recommended 30-day period, and even a 2-week course of therapy was unusual.29
Except for the few patients who could be kept in a dry and hygienic environment, the response to treatment was uneven at best. On a group basis, it was difficult to tell whether this was primarily because of adverse environmental factors (it was proposed that griseofulvin might be leached
29See footnote 2, p. 60.
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out of the skin by water30), failure to take the treatment as prescribed, or resistance of the organisms to antifungal antibiotics. The last possibility seemed less likely than the first two.
In acute, inflamed lesions, topical steroids were helpful in reducing inflammation and relieving symptoms. Use of tolnaftate and Whitfield's ointment was contraindicated because they were irritating to raw surfaces and only increased the patient's discomfort.
A few patients, primarily those with very extensive lesions that did not respond to outpatient therapy, were hospitalized for treatment. It was difficult to determine whether their improvement following hospitalization
30See footnote 2, p. 60.
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was principally because of the beneficial effects of air-conditioning and simple hygienic measures or because of stricter adherence to the therapeutic regimen.
Prevention.-The only sure way to prevent serious infections and reduce disability was to limit the amount of exposure to adverse environmental conditions. In infantry units, this meant limiting the duration of combat operations in wet terrain and providing time and facilities so that the men could allow their skin to dry. The high rates of morbidity from skin diseases forced this course of action in the U.S. 9th Infantry Division, and commanders were ordered to allow a full 24-hour 'standdown' period in a dry base camp between every 48-hour period of exposure to field conditions. This significantly reduced the rates of severe skin infections, but also became the chief limiting factor in the duration of combat operations.
Two other approaches to the prevention of fungal skin infections also were employed on an experimental basis: (1) administration of prophylactic griseofulvin and (2) provision of lightweight, fast-drying items of
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footwear. Both were alleged to be successful on the basis of field trials carried out in combat units, but their effectiveness was never definitively determined.
Griseofulvin was first seriously considered as a prophylactic agent for troops in 1967. Early, small-scale field trials indicated that prophylactic administration of 0.5 gram of micropulverized griseofulvin daily to each man in a combat unit would reduce the incidence of dermatophytosis by as much as sevenfold.31 Subsequent studies using larger numbers of subjects were not so encouraging,32 and in the final trial, there was no significant difference between the griseofulvin-treated and placebo-treated groups in the incidence of dermatophytosis.33 A randomized, double-blind trial involving subjects experimentally infected with T. mentagrophytes in the United States revealed that griseofulvin provided significant protection against the development of florid inflammatory lesions, but did not prevent
31(1) Report, Lt. Col. Nicholas F. Conte, MC, USARV Medical Consultant, to Surgeon, USARV, October 1968, subject: End of Tour Report. (2) Akers, William A.: Prophylactic Griseofulvin Against Trichophyton mentagrophytes Infections. In The Diagnosis and Treatment of Fungal Infections (Harry M. Robinson, Jr., editor). Springfield: Charles C. Thomas, Inc., 1974, p. 543.
32See pages 533-551 of footnote 31(2).
33Allen, Alfred M., and Taplin, David: Epidemiology of Cutaneous Mycoses in the Tropics and Subtropics: Newer Concepts. Proc. Third Internat. Conf. on Mycoses, Sao Paulo, Brazil, 27-29 August 1974. Pan Am. Health Org. Sc. Pub. No. 304, 1975.
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appearance of minimal signs of infection in most of the drug-treated subects.34
Prophylactic griseofulvin was issued to all men in the 10 maneuver battalions of the U.S. 9th Infantry Division during the rainy seasons in 1968 and 1969.35 This action did not have a marked effect on the rates of disability from dermatophytosis. The reasons for the failure of prophylactic griseofulvin to eradicate the epidemic of disability ringworm infections were not discovered, but the possibilities included failure to take the medication regularly as prescribed and leaching of the drug from the stratum corneum by sweat and paddy water.36
The usefulness of drying the feet to prevent fungal infections was clearly recognized in World War II,37 but measures to implement this action remained difficult to put into practice under wartime conditions. The heavy losses of combat manpower in Vietnam caused by fungal skin infections and immersion foot led to high-level interest in developing
34Allen, Alfred M., Reinhardt, Jeffrey H., Akers, William A., and Gunnison, Douglas: Griseofulvin in the Prevention of Experimental Human Dermatophytosis. Arch. Dermat. 108: 233-236, August 1973.
35Letter, Lt. Col. Archibald W. McFadden, MC, Surgeon, U.S. 9th Infantry Division, to all medical sections/units in the Division, 23 May 1969, subject: Surgeon's Information Letter 31-69: Use of Griseofulvin.
36See footnote 2, p. 60.
37See footnote 7, p. 61.
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effective means to prevent these conditions. Nowhere was this more apparent than among those responsible for developing new and improved items of clothing and footwear for the Army. A great deal of time, effort, and money was put into the development of boots and socks that would dry quickly after wetting and be light in weight even after walking in water and thick, tenacious mud (fig. 26). The final result of these efforts was that three new items of footwear-a lightweight nylon sock, a slide fastener for the tropical combat boot, and a lightweight comfort shoe-were adopted in March 1970 as Standard A items for Zones 1 and 2 (Hot, Tropical Areas).38
The first footwear item to be developed was a nylon mesh boot with an extremely coarse weave to promote drainage of water and to permit maximum aeration of the foot. The so-called 'Taft boot,' named after Lt. Col. Foster H. Taft, Jr., MC, the Surgeon of the 9th Division who originated the idea, had excellent drying qualities but was rejected because grit and small stones entered through the coarse weave and created erosion on the skin of the feet. A variety of other boot types were also tested, including boots with Nomex or nylon duck uppers and jungle boots with
38Swain, D. S., and Spaeth, J. F.: Footwear for Inundated Areas. Technical Report 73-57-CE, Clothing and Personal Life Support Equipment Laboratory, U.S. Army Natick Laboratories, July 1973.
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extra drain holes, but none possessed significant advantages over the standard canvas and leather jungle boot. A slide fastener (zipper) which was installed into the lace area of the jungle boot allowed the boot to be put on and taken off more easily and therefore was adopted as a new standard item. Few of these slide fasteners were actually worn and found suitable under combat conditions, however, and consequently their true value to the foot soldier was never fully established.
The standard Army sock worn by American soldiers in Vietnam was cushion-soled and composed of 50 percent wool, 30 percent cotton, and 20 percent nylon. It held a great deal of water when wet and was slow to dry. Two alternative types of socks were developed and tested as substitutes, one of nylon-cotton mesh and one of stretch nylon. The latter was found to be superior to the standard sock for use in wet tropical areas, and 500,000 pairs were shipped to the 9th Infantry Division in the Mekong Delta. These new socks were not used long in the field because the 9th Division was sent home from Vietnam shortly after their arrival.
A lightweight comfort shoe (essentially a very light tennis shoe) was developed to provide an alternative to the combat boot when men were in base camp or in defensive positions at night. These shoes proved popular in base camp but were of little use in the field at night because the extremely thin soles offered little protection against stones and other hard or sharp objects on the ground. Like the other footwear items developed by the U.S. Army Natick Laboratories, the comfort shoes arrived in Vietnam too late in the war to receive a thorough evaluation under actual field conditions.
Cutaneous Candidiasis
History and military significance.-Individually, yeast infections of the skin have had much the same military significance as dermatophyte infections. However, except in certain high risk populations such as cooks and boilerroom workers employed in extremely hot and humid environments,39 their cumulative effect has not been nearly so great as that of dermatophytosis.
Epidemiology.-Candidiasis of the skin was much less prevalent among troops in Vietnam than was dermatophytosis. In one survey of troops in the Mekong Delta,40 10 percent of the men with clinical evidence of cutaneous mycosis yielded Candida albicans on culture, frequently in association with a dermatophyte. Ninety percent of the infections were in the groin and toeweb areas.
39Report, Dermatologic Team of the Commission on Cutaneous Diseases, AFEB, to the President, AFEB, 15 Jan. 1968, subject: Report on Trip to Vietnam.
40See footnote 1, p. 59.
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Since C. albicans is part of the normal gut flora, it was presumed that those found on the skin probably were derived from that source rather than from contagion. In surveys carried out in the delta,41 perineal carriage of C. albicans could be detected in 16 percent of 245 U.S. infantrymen, 6 percent of 101 U.S. support troops, and zero percent of 80 Vietnamese rice farmers, thus indicating that the presence of C. albicans on the skin was strongly correlated with environmental factors and possibly with racial factors as well.
Etiology.-Virtually all cutaneous yeast infections were caused by C. albicans. Other species, such as C. tropicalis, were recovered on occasion, but there was no indication that they were important in causing disease.
In the presence of organisms, prolonged occlusion of the skin is all that is required to produce typical cutaneous candidiasis in an otherwise healthy person.42 This accounts for the frequent appearance of candidiasis of the groin in obese men with apposing thighs.
Clinical features.-Lesions usually were located in either the toewebs or the groin. Typical groin lesions presented as moist, red eruptions surrounded at the periphery by satellite papules (fig. 27). Lesions in the toe-
41Allen, Alfred M., and Taplin, David: Epidemiology of Dermatophytosis in the Mekong Delta. In Fungous and Bacterial Skin Infections in the Tropics, Annual Progress Report, by Harvey Blank and David Taplin, to the U.S. Army Medical Research and Development Command, March 1970, pp. 14-25.
42Maibach, Howard I., and Kligman, Albert M.: The Biology of Experimental Human Cutaneous Moniliasis (Candida albicans). Arch. Dermat, 85: 233-257, February 1962.
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webs and axillae and on the glans penis had moist pink or fiery red surfaces overlain at the periphery by thick, white, curdlike plaques (figs. 28-30).
Symptoms consisted of severe itching and burning sensations. Symptoms were made worse by pressure from clothing and by rubbing together of apposing skin surfaces, as in the groin while walking.
Diagnosis.-Lesions in the toewebs and in other intertriginous areas except the groin usually could be correctly diagnosed on the basis of physical examination alone. The groin presented a special problem because the lesions were seldom 'typical' and were difficult to differentiate from tinea cruris and intertrigo. Cultures and microscopic examination of scrapings from the lesions assisted in making the diagnosis, as did trials of specific therapy using nystatin. However, these approaches were not optimal because of the scarcity of laboratory diagnostic aids and the delays involved in establishing the correct diagnosis.
Prognosis.-Recurrences of infection were frequent and apt to take place as soon as the patient was reexposed to the same environmental conditions from which he came.
Treatment.-Treatment consisted of topical applications of nystatin (Mycolog) and corticosteroids. Attention also was directed toward providing relief from macerating or occlusive conditions of the skin, if possible.
Prevention.-The mainstays in successful prevention of cutaneous candidiasis were (1) providing dry clothing and (2) allowing the intertriginous skin areas to dry at frequent intervals. These measures were of limited value because they were difficult to put into practice, especially during the rainy season.
Tinea Versicolor
Military significance.-Tinea versicolor is of no military importance from the standpoint of physical discomfort and disability; however, in Vietnam it was a frequent cause of outpatient visits and caused concern because many troops thought it was a cutaneous manifestation of venereal disease.
Etiology.-Tinea versicolor results from colonization of the superficial, horny layer of the skin by a nondermatophyte fungus, Malassezia furfur. Nothing suggested that the infecting organisms in Vietnam were different from those in the United States.
Hot, humid weather is an important predisposing factor and undoubtedly accounted for the large number of infections in Vietnam.
Clinical features.-Tinea versicolor among troops in Vietnam was typical in appearance-multiple, coalescent macular patches distributed on the upper trunk, neck, face, and upper arms. In most instances, the light brown scale produced by the infection had rubbed off, leaving depigmented areas that did not tan on exposure to sunlight. The degree of depigmenta?
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tion in dark-skinned persons was often striking (fig. 31), but the loss of pigment was only temporary.
Most cases were completely asymptomatic; however, in a few cases there was mild pruritus.
Diagnosis.-Most diagnoses of tinea versicolor were based on appearance alone. Occasionally the lesions could be confused with vitiligo or mild dermatophytosis; in these, the characteristic scale could be made visible by gently scraping the periphery of a lesion. To resolve residual cases of doubt, microscopic examination of the scale in 10-percent potassium hydroxide solution was useful in revealing the causative organisms (round yeast cells and fragments of hyphae).
Treatment.-Applications of selenium sulfide solution (Selsun) were highly effective in ridding the patient of lesions,43 but recurrences were frequent as soon as treatment was discontinued. Response to therapy was enhanced if the solution was allowed to dry on the skin rather than being rinsed off soon after application.
Griseofulvin and tolnaftate were not effective in treating tinea versicolor.
Prevention.-No effective preventive measures existed.
BACTERIAL INFECTIONS
Skin infections caused by bacteria were second only to fungal infections in frequency of occurrence and amount of disability produced.44 Nearly all were caused by Streptococcus pyogenes, Staphylococcus aureus, or both. The term 'pyoderma' was used to refer to this class of infection as a whole.
Generally speaking, pyodermas in Vietnam were no different in etiology and clinical characteristics than those in the United States.45 So-called 'jungle sores' were not caused by an unusual or exotic group of organisms but were ecthymatous ulcers caused by streptococci. However, the incidence and severity of these infections were far greater than in comparable military populations in the United States. Heat, humidity, dirt, insect bites, cuts, scratches, and poor hygiene all combined to initiate and aggravate bacterial skin infections. This was especially true in infantrymen who had maximal exposures to the inciting factors and minimal opportunities for bathing and basic skin care.
Bacterial skin infections were a leading cause of lost time from combat duty in Vietnam.46 This was not reflected in official statistics because most
43Dermatologic Problems. USARV Med. Bull. (USARV Pam 40-13), January-February 1969, pp. 25-27.
44See footnote 1, p. 59.
45Allen, Alfred M., Taplin, David, and Twigg, Lewis: Cutaneous Streptococcal Infections in Vietnam. Arch. Dermat. 104: 271-280, September 1971.46(1) See footnotes 1, p. 49; and 45. (2) England, Robert L.: Skin Ulcers in Combat Infantry Troops Operating in Jungle Terrain. USARV Med. Bull. (USARV Pam 40-18), November-December 1969, pp. 38-41.
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cases were not hospitalized for treatment. Instead, the patient was placed on light duty status until his lesions had healed sufficiently for him to return to full combat duty (fig. 32). This ordinarily resulted in losses of time from field duty ranging from 2 to 10 days per man per case.
Prevention and treatment of these lesions were major problems throughout the war. Competent, well-trained physicians knew little about the diagnosis and management of the common forms of pyoderma. As a result, the choice of therapy tended to be haphazard and inappropriate. A quotation from a physician who served with the U.S. Army in Vietnam summarized the prevalent philosophy of treatment: 'I don't know what it is, but in Vietnam, I treat it by the 'it' method * * * intuition and tetracycline.' Indeed, tetracycline was the most commonly used systemic anti-
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biotic for the treatment of pyoderma, and its use for this purpose was recommended in the USARV (U.S. Army, Vietnam) Medical Bulletin.47 Ironically, antibiotic sensitivity studies showed tetracycline to be one of the least effective agents for treatment of streptococcal pyoderma.48
With respect to pyoderma, the most important advance made during the Vietnam war was the recognition that these apparently trivial infections are a major military medical problem in the Tropics. Those who attempted to prevent and treat pyoderma found that simplistic solutions were of little avail and that lesions tended to grow in size and number despite the most strenuous efforts at control. Progress was made not only
47See footnote 43, p. 87.
48See footnote 45, p. 87.
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in recognizing the problem but also in better defining these infections both clinically and epidemiologically.49
Streptococcal Pyoderma
History and military significance.-Pus-forming skin infections caused by coccal bacteria were first clearly defined and described by Tilbury Fox and Sabouraud in the late 19th century. It was recognized that both streptococci and staphylococci usually could be recovered from the lesions and that these coccal bacteria were the primary etiologic offenders.
With the possible exception of cutaneous diphtheria, bacterial skin infections were not believed to be a major medical problem among military forces until the war in Vietnam.50 However, careful scrutiny of historical records from World War II indicates that ecthyma and impetigo were larger problems than senior medical officers realized at the time.
49(1) See footnote 45, p. 87. (2) Dillon, Hugh C., Jr.: Impetigo Contagiosa: Suppurative and Non?Suppurative Complications. I. Clinical, Bacteriologic, and Epidemiologic Characteristics of Impetigo. Am. J. Dis. Child. 115: 530-541, May 1968. (3) Wannamaker, Lewis W.: Differences Between Streptococcal Infections of the Throat and of the Skin. New England J. Med. 282: 23-31 (1 Jan. 1970), 78-85 (8 Jan. 1970).
50See footnote 7, p. 61.
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An example can be taken from a postwar paper by Liebow.51 Attention was centered on the fact that virulent diphtheria bacilli were recovered from 18 percent of 790 skin ulcers in infantrymen from three divisions in the Southwest Pacific. Only in passing was it mentioned that 51 percent of these lesions yielded Streptococcus pyogenes and 52 percent yielded Staphylococcus aureus.
Epidemiology.-The most important factors in the epidemiology of streptococcal pyoderma among U.S. troops in Vietnam were race, level of hygiene, and exposure to multiple sources of trauma to the skin.52 Among Americans, pyoderma was both more frequent and more severe in infantrymen than in support troops (table 19) and was more than twice as common in white soldiers as in black soldiers (table 20).
TABLE 19.-Prevalence of pyoderma in four population groups in the Mekong Delta
Population | Number surveyed | Percent with pyoderma |
American infantrymen | 497 | 18.9 |
American support troops | 222 | 12.6 |
Vietnamese infantrymen | 93 | 7.5 |
Vietnamese adult civilians | 76 | 6.6 |
Source: Allen, Alfred M., Taplin, David, and Twigg, Lewis: Cutaneous Streptococcal Infections in Vietnam. Arch. Dermat. 104: 271-280, September 1971.
TABLE 20.-Prevalence of pyoderma by race in American soldiers in Vietnam
Population | White soldiers | Black soldiers | Ratio of prevalences | ||
Number surveyed | Prevalence, percent | Number surveyed | Prevalence, percent | ||
Infantrymen | 406 | 20.9 | 77 | 7.8 | 2.68:1 |
Support troops | 196 | 9.7 | 27 | 3.7 | 2.62:1 |
Source: Allen, Alfred M., Taplin, David, and Twigg, Lewis: Cutaneous Streptococcal Infections in Vietnam. Arch. Dermat. 104: 271-280, September 1971.
Vietnamese adults, both military and civilian, were infected significantly less often than were Americans with similar environmental exposures (table 19).
The differences in frequency and severity of infections between infantrymen and support troops could be explained by greatly different rates of exposure to environmental stresses such as insect bites, cuts, and scratches. However, the differences between black and white soldiers, and between Americans and Vietnamese, could not be explained so easily. Pyoderma was highly prevalent in Vietnamese children and in black children in the United
51Liebow, Averill A., MacLean, Paul D., Bumstead, John H., and Welt, Louis G.: Tropical Ulcers and Cutaneous Diphtheria. Arch. Int. Med. 78: 255-295, September 1946.
52See footnotes 45 and 46 (2), p.87.
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States, suggesting that the racial differences in prevalence of infection among adults were not related to a genetic effect but may have been caused by immunity acquired by virtue of multiple infections in childhood.
Etiology.-Typical 'jungle sores' yielded Streptococcus pyogenes and Staphylococcus aureus in 80 to 90 percent of cases (tables 21 and 22), provided
Organisms | Number of cases | Percent |
Beta-hemolytic Streptococcus and Staphylococcus aureus | 34 | 68 |
Streptococci only | 6 | 12 |
Staphylococci only | 7 | 14 |
Other | 3 | 6 |
| Total | 50 | 100 |
Source: McMillan, Michael R., and Hurwitz, Robert M.: Tropical Bacterial Pyoderma in Vietnam: An Improved Therapeutic Regimen. J.A.M.A. 210: 1734-1736, 1 Dec. 1969.
TABLE 22.-Results of culture in 36 men requiring treatment for pyoderma in the Mekong Delta
Organisms | Number of cases | Percent |
Beta-hemolytic Streptococcus and Staphylococcus aureus | 26 | 72 |
Streptococci only | 6 | 17 |
Staphylococci only | 2 | 5 |
Other | 1 | 3 |
No growth | 1 | 3 |
| Total | 36 | 100 |
Source: Allen, Alfred M., Taplin, David, and Twigg, Lewis: Cutaneous Streptococcal Infections in Vietnam. Arch. Dermat. 104: 271-280, September 1971.
appropriate culture media were used.53 Nearly all of these infections arose at the site of small breaks in the skin caused by minor cuts, scratches, and insect bites (fig. 33). Serologic typing of streptococci and phage typing of staphylococci were not helpful in establishing patterns of infection.54
Unlike the experience in World War II, there was no indication that cutaneous diphtheria occurred in American troops.
Clinical features.-Streptococcal skin infections appeared in three major clinical forms: impetigo, ecthyma, and cellulitis. Erysipelas was not seen..
Impetigo usually occurred around the nose, lips, and ears and appeared as superficial, honey-colored, 'stuck-on' crusts (fig. 34).
53(1) See footnote 45, p. 87. (2) McMillan, Michael R., and Hurwitz, Robert M.: Tropical Bacterial Pyoderma in Vietnam: An Improved Therapeutic Regimen. J.A.M.A. 210: 1734-1736, 1 Dec. 1969.
54See footnote 45, p. 87.
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Ecthyma was the more common and serious form of infection.55 Most lesions were located on the extremities (table 23), particularly the hands, feet, and ankles. Typical lesions began at the site of an insect bite or scratch (the portal of entry) and progressively enlarged to form a painful, tender, round or oval ulcer measuring up to 3 cm. in diameter. Upon removal of dirty grayish-yellow crusts, the ulcers presented a sharply punched-out appearance, with slightly overhanging margins and a pink, granulating base (fig. 35). There was often a zone of erythema and induration around the ulcers, but ascending lymphangitis and regional lymphadenitis were rare. Multiple ecthymatous ulcers on a single extremity were common (fig. 36).
Location | Number of cases | Percent |
Lower extremities only | 27 | 54 |
Upper extremities only | 3 | 6 |
Upper and lower extremities | 15 | 30 |
Face and extremity | 2 | 4 |
Buttock and extremity | 3 | 6 |
| Total | 50 | 100 |
Source: McMillan, Michael R., and Hurwitz, Robert M.: Tropical Bacterial Pyoderma in Vietnam: An Improved Therapeutic Regimen. J.A.M.A. 210: 1734-1736, 1 Dec. 1969.
Cellulitis of the lower extremities was rare in comparison with impetigo and ecthyma. This kind of infection was usually unilateral and seemed to develop from the site of an antecedent skin infection, such as ecthyma or dermatophytosis, or from a minor break in the skin, such as a fissure between the toes. It presented as a painful, red, hot, tense, tender swelling of the affected part.
Diagnosis.-The diagnosis of pyoderma was based on physical examination. Few physicians had access to laboratories where cultures could be performed, and therefore most were forced to rely on clinical impressions rather than on cultures for a specific etiologic diagnosis. When cultures were performed, few yielded beta-hemolytic streptococci because the techniques required to isolate and identify these organisms were not routinely used by supporting laboratories.56 For this and other reasons,57 many physicians were under the impression that they were dealing with antibiotic?resistant staphylococcal infections or with an exotic tropical infection of uncertain etiology. Relatively few were aware that the vast majority of 'jungle sores' and related skin lesions were streptococcal in origin. This
55See footnote 45, p. 87.
56See footnote 39, p. 82.
57See footnote 53 (2), p. 92.
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had profound consequences in attitudes and beliefs toward management and treatment of pyoderma.
Prognosis and complications.-Under combat conditions, ecthymatous ulcers in infantrymen could last for weeks if not properly treated (fig. 37). It was not unusual to find soldiers who were on light duty for a month or more because of ecthyma. Additionally, a new crop of lesions was frequently found just as old ones had healed, thereby lengthening the period of recovery. However, extension of infection in the form of spreading cellulitis and lymphangitis was rare as a complication of impetigo and ecthyma.
Acute glomerulonephritis is a well-recognized complication of cu-
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FIGURE 36.-Multiple streptococcal pyodermas on dorsum of foot. Note surrounding inflammation.
taneous streptococcal infections;58 however, no cases of acute glomerulonephritis were known in the American troop population despite the vast number of infections that existed. It is likely that this was because of the age of soldiers, since nephritogenic M-types of streptococci were at times recovered from the lesions and acute glomerulonephritis was known to exist in Vietnamese children.59
58(1) See footnote 49 (3), p. 90. (2) Dillon, Hugh C., and Wannamaker, Lewis W.: Skin Infections and Acute Glomerulonephritis: Report of a Symposium. Mil. Med. 136: 122-127, February 1971.
59(1) Letter, Lewis W. Wannamaker, M.D., Director, Commission on Streptococcal and Staphylococcal Diseases, AFEB, to David Taplin, Member, Commission on Cutaneous Diseases, AFEB, 30 Sept. 1968, subject: Streptococci From Vietnam. (2) Memorandum, Harvey Blank, M.D., Director, Commission on Cutaneous Diseases, AFEB, to David Taplin, Member, Commission on Cutaneous Diseases, 20 May 1969, subject: Acute Glomerulonephritis in Vietnamese Children.
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Treatment.-There was no standard method of treating pyoderma in Vietnam. Most often, physicians were forced to rely on their judgment and experience in selecting a form of therapy. Topical antibiotic preparations such as neomycin or bacitracin ointment were prescribed for the majority of patients, usually with disappointing results. Systemic antibiotics were reserved for the most severe cases. Tetracycline was the agent most frequently prescribed, both for its broad spectrum of antimicrobial activity and for its freedom from serious side effects compared with antibiotics such as penicillin. Only toward the end of American involvement in the war was it realized that most of the pyodermas were caused by streptococci and that a majority of these organisms were resistant to tetracycline (table 24).
In addition to antibiotic therapy, treatment included vigorous removal of crusts overlying the lesions, thorough debridement, and soaks in a soap solution containing the antibacterial agent hexachlorophene (pHisoHex). This procedure was recommended both in the USARV Medical Bulletin60 and in the field manual 'Management of Skin Diseases by Company Aidmen in the Tropics.'61 The questionable value of this form of treatment was made apparent when Army-sponsored research showed that vigorous
60See footnote 43, p. 87.
61Field Manual (FM) 8-40, Headquarters, Department of the Army, 22 Aug. 1969, subject: Management of Skin Diseases by Company Aidmen in the Tropics.
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Population | Number of cultures | Percent resistant | ||
Penicillin | Erythromycin | Tetracycline | ||
U.S. infantrymen | 99 | 0 | 6 | 46 |
U.S. support troops | 32 | 0 | 3 | 78 |
Vietnamese civilians | 16 | 0 | 12 | 69 |
Source: Allen, Alfred M., Taplin, David, and Twigg, Lewis: Cutaneous Streptococcal Infections in Vietnam. Arch. Dermat. 104: 271-280, September 1971.
debridement of pyodermas is unnecessary and possibly harmful, while hexachlorophene soaks may actually retard healing (fig. 38).62
Antibiotic treatment based on routine culture and sensitivity studies also tended to be inappropriate. For reasons indicated in the section on diagnosis (p. 94), the information generated by cultures gave the false impression that most of the pyodermas were caused by penicillin-resistant staphylococci. Consequently, penicillinase-resistant antibiotics such as oxacillin were needlessly prescribed.63
Studies carried out in Vietnam64 and in the United States during the late 1960's demonstrated that penicillin or erythromycin was the treatment of choice for streptococcal pyoderma. One intramuscular injection of 600,000 units of long-acting benzathine penicillin G (Bicillin) in adults was more effective than a 10-day course of phenoxymethyl penicillin potassium (Pen-Vee K) in a dose of 400,000 units taken orally three times a day.65
A 'one shot' treatment with benzathine penicillin possessed enormous administrative advantages over orally administered antibiotic therapy. However, this agent was little used for the treatment of pyoderma in Vietnam because its efficacy in this condition was not demonstrated until the end of American involvement in the war. Oral penicillin and erythromycin were used with success, particularly by dermatologists,66 but any medication requiring oral administration was of limited value in the treatment of infantrymen. The reasons for this were administrative in nature and included difficulties in keeping the medication intact and dry, forgetting to take the medication while under the stresses of combat, and lack of motiva?
62Dajani, Adnan S., Hill, Patty Lee, and Wannamaker, Lewis W.: Experimental Infection of the Skin in the Hamster Simulating Human Impetigo. II. Assessment of Various Therapeutic Regimens. Pediatrics 48: 83-90, July 1971.
63See footnote 53 (2), p. 92.
64See footnote 45, p. 87.65(1) Dillon, Hugh C., Jr.: The Treatment of Streptococcal Skin Infections. J. Pediat. 76: 676-684, May 1970. (2) Derrick, C. Warren, and Dillon, Hugh C., Jr.: Further Studies on the Treatment of Streptococcal Skin Infection. J. Pediat. 77: 696-700, October 1970.
66Watt, Thomas L.: Dermatology in Southeast Asia. [Unpublished account of Lieutenant Colonel Watt's professional experiences in Vietnam, 1968-69.]
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tion to treat infections which might provide a convenient excuse to avoid field duty.
Cellulitis was treated with bed rest, elevation and immobilization of the affected part, and intramuscular or intravenous penicillin. The response to this form of treatment was satisfactory.
Prevention.-No specific measures were available for preventing streptococcal skin infections. General measures included frequent bathing with antibacterial soaps,67 maintaining general cleanliness and personal hygiene, and promptly treating infected cuts and scratches. As a practical matter,
67(1) Duncan, W. C., Dodge, B. G., and Knox, J. M.: Prevention of Superficial Pyogenic Skin Infections. Arch. Dermat. 99: 465-468, April 1969. (2) MacKenzie, Albert R.: Effectiveness of Antibacterial Soaps in a Healthy Population. J.A.M.A. 211: 973-976, 9 Feb. 1970.
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these measures were difficult to apply to field troops who were at high risk of developing infections.
Staphylococcal Infections
History and military significance.-Skin infections caused by staphylococci accounted for a significant proportion (≈5 percent) of patients admitted to hospitals for skin diseases in Vietnam.68 This experience was similar to that of previous wars.69 However, unlike streptococcal pyoderma, staphylococcal skin infections did not occur in epidemic form, and the total amount of disability was far less.
Etiology.-Nearly all staphylococcal skin infections of consequence in Vietnam were caused by coagulase-positive strains (Staphylococcus aureus). Many were resistant to penicillin and tetracycline.70 Sweat, grime, and contact with lubricants were thought to be important precipitating factors in cases of furunculosis.
Bullous impetigo was also caused by coagulase-positive staphylococci. In the United States, bullous impetigo in children was caused by Staphylococcus aureus of phage type 71 or by closely related group 2 strains. These infections occurred in the absence of trauma to the skin.71
Clinical features.-The clinical features of staphylococcal skin infections in Vietnam were no different than those in the United States. Furuncles (boils) were particularly troublesome when they occurred in multiple form in a single patient (furunculosis) (fig. 39). Under field conditions, such as on long-range patrols, boils would be neglected for many days and hospitalization was frequently required.
Bullous impetigo, a distinct clinical variant not related to streptococcal impetigo,72 occurred occasionally in soldiers and presented a problem because of its unusual appearance. Multiple flaccid bullae, 1 to 2 cm in diameter and containing clear or cloudy fluid, appeared de novo, usually on the trunk near the axillae. When ruptured, the lesions dried to form a thin, varnishlike crust (fig. 40). The exposed bases of ruptured bullae were susceptible to secondary infection by streptococci (fig. 41). In the absence of secondary infection, these lesions healed without scarring.
Treatment.-Treatment of pus-containing lesions (furuncles, carbuncles, paronychia) included drainage and compresses. In the absence of cultures and antibiotic sensitivity studies, orally administered erythromycin or a penicillinase-resistant variant of penicillin (such as oxacillin) was the antibiotic treatment of choice. Nearly all strains of Staphylococcus
68Report, Patient Administration and Biostatistics Office, Office of the Surgeon General, 31 Mar. 1975, subject: Dermatologic Conditions in Vietnam, 1965-1970.
69See footnote 11, p. 62.
70See footnotes 45, p.87; and 53 (2), p. 92.
71See footnotes 49 (2) and (3), p. 90.72See footnotes 49 (2) and (3), p. 90.
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FIGURE 39.-Furunculosis (multiple boils) in an American soldier in Vietnam.
aureus recovered from the skin were sensitive to these antibiotics, whereas a large proportion were resistant to penicillin and tetracycline (table 25).
TABLE 25.-Antibiotic resistance of Staphylococcus aureus cultured from pyoderma lesions of U.S. troops in Vietnam and of Vietnamese
Population | Number of cultures | Percent resistant | ||
Penicillin | Erythromycin | Tetracycline | ||
U.S. infantrymen | 129 | 85 | 2 | 40 |
U.S. support troops | 32 | 88 | 3 | 24 |
Vietnamese civilians | 26 | 96 | 39 | 65 |
Source: Allen, Alfred M., Taplin, David, and Twigg, Lewis: Cutaneous Streptococcal Infections in Vietnam. Arch. Dermat. 104: 271-280, September 1971.
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Bullous impetigo was satisfactorily treated by rupturing the bullae and administering erythromycin orally.
IMMERSION INJURIES OF THE FEET
Immersion injuries of the feet were a common cause of temporary disability among infantrymen in wet, lowland areas of Vietnam. After long patrols in swamps and flooded rice paddies, as many as half of the men in each unit developed immersion injuries of various degrees of severity. In some, pain and swelling involving the feet were so severe that the men had to be evacuated from frontline operational areas to hospitals in the rear.
Two types of immersion injury of the feet occurred in Vietnam, one that primarily involved the dorsal surfaces and the ankles, and another that was restricted to the soles.73 A variety of terms were applied to these
73(1) See footnote 61, p. 97. (2) Allen, Alfred M., and Taplin, David: Tropical Immersion Foot. Lancet 2: 1185-1189, 24 Nov. 1973. (3) Akers, William A.: Paddy Foot: A Warm Water Immersion Foot Syndrome Variant. Part I. The Natural Disease, Epidemiology. Mil. Med. 139: 605-618, August 1974.
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conditions, including tropical immersion foot, warm water immersion foot, paddy foot, and jungle rot. Often these terms were used interchangeably to refer to one or the other of the two basic types of injury, thereby producing a great deal of confusion.
In the following account, the term 'tropical immersion foot' applies to injuries involving the dorsa and ankles, and the term 'warm water immersion foot' refers to injuries of the plantar surfaces. The distinguishing features of tropical immersion foot and warm water immersion foot are outlined in table 26.
Tropical Immersion Foot
History and military significance.-Classical immersion foot has been recognized since the early part of the 19th century.74 It is a form of non-freezing cold injury. Thousands of cases occurred among U.S. military personnel in Europe during World War II, and at times the incidence was high enough to seriously jeopardize military operations.75 Many of the afflicted men suffered loss of tissue and resultant permanent disability.
In contrast, tropical immersion foot is a relatively new entity. The original description was based on cases among American soldiers fighting to retake the Philippines during World War II.76 Maj. (later Lt. Col.) Frank Glenn,77 the Army surgical consultant in the Pacific, examined 120 of these men shortly after admission to evacuation hospitals and noted that their signs and symptoms closely resembled those of immersion injuries sustained in cold climates. Consequently it was believed that this new syndrome was 'a type of cold injury low on the gradient.'
The possibility that cold injuries might occur in the Tropics generated a great deal of interest at the time, but wartime restrictions precluded confirmatory studies. No photographs or biopsies were obtained. Fungal cultures obtained in the acute stages were negative, leading Hopkins and Webster to suggest that the essential pathogenic factor was maceration of the stratum corneum after prolonged immersion.78
Tropical immersion foot emerged again as an important medical problem in combat troops upon active American involvement in the Vietnam war. Wet foot casualties occurred in profusion in U.S. Army ground combat units operating in wet, lowland areas, such as the Mekong Delta.79 Together with other foot problems caused by fungal and bacterial infection,
74Paddy-Field Foot. Lancet 1: 1043, 13 May 1967.
75Whayne, Tom F., and DeBakey, Michael E.: Cold Injury, Ground Type, in World War II. Washington: U.S. Government Printing Office, 1958, pp. 127-216.
76See footnote 75.
77Glenn, Frank: Tropical Jungle Foot. In Medical Department, United States Army. Surgery in World War II. Activities of Surgical Consultants, vol. I. Washington: U.S. Government Printing Office, 1962, pp. 492-494.78See footnote 7, p. 61.
79See footnote 73, p. 102.
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TABLE 26.-Distinguishing features of tropical immersion foot and warm water immersion foot
Feature | Tropical immersion foot | Warm water immersion foot |
Clinical: | ||
| Site of involvement | Ankles and dorsa of feet | Soles |
| Symptoms | Burning pain aggravated by pressure from footwear and by walking | Pain on weight bearing; tingling; "walking on rope" sensation |
| Signs | Symmetrical erythema, edema, and tenderness; line of demarcation at boot top level | Swelling, wrinkling, and pallor |
| Systemic involvement | Fever and femoral lymphadenopathy (severe cases) | None |
| Healing time | 3-10 days | 1-3 days |
Pathology: | ||
| Epidermis | Parakeratosis and acanthosis | Thickening of stratum corneum |
| Dermis | Chronic inflammatory cells (lymphocytes, monocytes, eosinophils, and plasma cells) in upper dermis; angiitis with endothelial proliferation; diapedesis; edema | No observed changes |
Pathogenesis (presumptive) | Passage of water through comprised epidermal barrier into upper dermis; reaction to hypotonic fluid | Hyperhydration ("water-logging") of plantar stratum corneum |
Epidemiology: | ||
| Water exposure required | 3-7 days | 1-3 days |
| Water temperature producing injury | 22? to 32? C (70? to 90? F) | 15? to 32? C (60? to 90? F). |
| Relation to water temperature | Not established | Increase in temperature hastens injury |
Susceptibility factors | Previous episodes of tropical immersion foot increase susceptibility | Thickness of plantar stratum corneum: heavy callouses predispose; thin soles protect. |
Prevention | Day-long drying of feet between 2-3 days of constant wetness | Overnight drying of feet; daily application of silicone grease |
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tropical immersion foot often accounted for more time lost from combat duty than all other medical causes combined.80
Epidemiology.-The occurrence of tropical immersion foot in Vietnam was strictly limited to men who had spent 3 or more consecutive days in inundated terrain, yet only a fraction of those at risk developed significant injury despite apparently equal exposures to water. Incidence data were not available at unit level, but commanders estimated that severe immersion injury developed in only 3 or 4 of each 100 men exposed to a wet environment over a 4-day period, and this impression was confirmed during interviews with patients.
Tropical immersion foot occurred year-round in wet areas, such as the Mekong Delta. The majority of cases appeared during the rainy season. There were marked seasonal differences in rainfall, but practically none in ambient temperature, relative humidity, and the temperature of surface waters. Thus, the incidence of immersion foot was correlated principally with the amount of rainfall, and this in turn governed the wetness of the swamps and paddies (figs. 42 and 43). Cases that occurred during the dry season were confined to units located in tidal river basins or heavily irrigated terrain.
There was little to indicate why some men were particularly susceptible to immersion injury while others were not. Factors such as race, body build, and length of tropical service seemed to be unimportant. The only predictive indicator was that of prior injury. Patients, medical officers, and infantry commanders all suggested that men who suffered a severe attack of tropical immersion foot were more susceptible to a second or third episode when again exposed to wet terrain.
Etiology.-The etiology of tropical immersion foot was a source of debate during the entire Vietnam conflict, with theories ranging from cold injury to the effects of microbial toxins.81 The only established fact was that a direct relationship existed between the occurrence of tropical immersion foot syndrome and prolonged exposure to water during combat operations. Studies conducted during the later stages of the war suggested that water itself may have been responsible for the dermatitis once it had gained entry to the dermis through macerated stratum corneum.82
Biopsies taken from the dorsum of the foot showed (1) acanthosis and parakeratosis of the epidermis, with swelling and fragmentation of the superficial layers of the stratum corneum; (2) dense chronic inflammatory cell infiltrates in the upper dermis, with edema and diapedesis of red blood cells; and (3) dermal vasculitis marked by perivascular collections of lymphocytes.83 In some cases, there was marked narrowing of the dermal
80See footnote 1, p. 59.
81Taplin, David, and Zaias, Nardo: Tropical Immersion Foot Syndrome. Mil. Med. 131: 814-818, September 1966.82Willis, Isaac: The Effects of Prolonged Water Exposure on Human Skin. J. Invest. Dermat. 60: 166-171, March 1973.
83See footnote 73 (2), p. 102.
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capillaries because of swelling and proliferation of the endothelial lining (figs. 44 and 45).
Clinical features.-The clinical features of tropical immersion foot in Vietnam were similar to those described in the Southwest Pacific during World War II.84 Patients invariably gave histories of prolonged immersion while on patrol in exceptionally wet terrain. Exposures to swamp and paddy water were virtually continuous for periods ranging from 4 to 10 days. Because of the tactical situation, the men were unable to remove their
84See footnote 73 (2), p. 102.
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wet boots and socks at night and were required to march, stand, or sleep in water to waist level or above.
The first indication of injury was a burning sensation in the feet, more pronounced on the dorsal surfaces than on the soles. Walking became progressively more painful, prompting the men to remove their footwear to examine their feet. Many of those who did soon found that their feet had become so swollen that they could not replace their boots. They were in obvious distress whenever they attempted to walk and were no longer fit for combat duty. Severe cases had to be evacuated by helicopter from hazardous operational areas to hospitals in the rear.
The significant findings on admission were marked pitting edema of the ankles and dorsa of the feet, intense erythema, and a clear line of demarcation at boot top level (figs. 46 and 47). The skin was unusually sensitive to touch and there was tenderness to deep pressure over the involved surfaces. Pain and tenderness were increased by weight bearing. The skin was cool to touch but became noticeably warm within 12 hours of admission. Pulses were full and capillary filling was brisk. Wet sock
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abrasions and small ulcerations over pressure points were commonly found in association with immersion foot (fig. 48). Hyperhydration and wrinkling of the plantar surfaces were early but transient features.
In contrast to the original descriptions of tropical immersion foot, systemic reactions were present in nearly every case severe enough to require hospitalization. The reactions consisted of fever and femoral lymphadenopathy. Oral temperatures ranged between 38? and 39? C. Femoral lymph nodes were moderately enlarged and tender, but there was no lymphangitis.
Following hospitalization, the first indications of improvement were loss of fever and adenopathy, marked reduction in pain and tenderness, and reversal of the changes involving the soles. These occurred within the first 48 to 72 hours following admission. After this time, the erythema of the dorsal surfaces and ankles was replaced by diffuse ecchymotic blotches, crops of tiny vesicles, and a fine maculopapular rash (figs. 49 and 50). Edema subsided over a period of 4 to 7 days. In the later stages, this was accompanied by a fine, branny desquamation of the skin over the involved areas. When this process was complete, the skin of the feet appeared completely normal and there were no detectable vasomotor changes.
110
Diagnosis.-Immersion foot was only one of several afflictions of the skin of the feet that were common after prolonged exposure to the watery delta environment. Accurate differential diagnosis was therefore critically important as a guide to proper treatment. The most important entities to be differentiated were streptococcal cellulitis, inflammatory dermatophytosis, and wet sock erosions. In contrast to immersion foot, cellulitis was usually unilateral, with intensely painful swelling of the lower limb. Dermatophytosis was distributed in patches and confluent rings rather than in the diffuse yet symmetrical fashion characteristic of immersion foot. Wet sock erosions were localized to areas of friction and pressure, such as the area under the bootlaces, and did not extend over the entire surface of the dorsum and ankle as did the lesions of tropical immersion foot.
Prognosis and complications.-Permanent physical changes did not occur as a result of acute tropical immersion foot. However, not every patient remained entirely free of residual effects. From interviews with patients, physicians, and military commanders, it became evident that men who had suffered a severe attack of immersion foot were increasingly susceptible to a second or third episode when again exposed to wet terrain.
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Treatment.-Treatment consisted of bed rest, elevation of the feet, and medication for pain and sleep. The feet were left uncovered and no topical medications were used. Systemic antibiotics were given only if the patient had a concomitant infection for which an antibiotic was indicated.
Recovery was rapid with this form of treatment, generally requiring no more than 4 or 5 days of hospitalization. Even the most severely affected patients healed completely within 10 to 12 days. In contrast to immersion injuries occurring in colder climates, gangrene did not supervene and no serious sequelae were known to occur. All of the patients were able to return to duty following hospitalization.
Not all cases of immersion foot required hospitalization. Many were
112
113
treated in forward areas. These cases were characterized by pain, tenderness, and erythema. They lacked edema and systemic reactions. Such cases resolved completely within 2 or 3 days if the feet were kept dry.
Prevention.-Military commanders in Vietnam found that tropical immersion foot casualties could be eliminated by insisting on 24-hour 'dry out' periods following every 48-hour period of exposure to wet terrain. At times such measures were impractical or unfeasible, and therefore alternative means of prevention were explored. Lightweight, fast-drying items of footwear were developed as possible alternatives to the standard jungle boot and cotton-wool sock combination.85 Although preliminary evaluations suggested that the use of these items could retard the onset of immersion injury, American participation in wet terrain operations was terminated before large-scale studies could be begun.
85See footnotes 38, p.81; and 73 (2), p. 102.
114
115
Contrary to the experience with warm water immersion foot, silicone ointment was never demonstrated to be effective in the prevention of tropical immersion foot.86
Warm Water Immersion Foot
History and military significance.-Warm water immersion foot was first described by Capt. Gustave T. Anderson, a U.S. Navy dermatologist, following a consultant trip to Vietnam in late 1965.87 At that time, U.S. marines in the northern coastal provinces of South Vietnam were sustaining massive wet-foot casualties after long patrols in water-soaked fields and paddies. Captain Anderson examined the afflicted marines and noted that the principal findings were confined to the soles of the feet, which were white, wrinkled, and painful, especially during weight bearing. He termed this form of injury 'warm water immersion foot.'88
Like tropical immersion foot, warm water immersion foot can be temporarily disabling to large numbers of ground combat troops operating in wet tropical areas. It can seriously reduce the combat effectiveness of infantry units.
Epidemiology.-Susceptibility to warm water immersion foot was found to vary widely among individual members of a unit. Those with thick, heavy callouses on the soles were the most susceptible, while those with a thin layer of plantar stratum corneum (baby feet) were the last to manifest this form of immersion injury.89
Warm water immersion foot began to appear after 24 hours of continuous exposure to water. By the end of 72 hours of exposure, nearly every man had some degree of involvement. Oddly, units that sustained tropical immersion foot casualties did not seem to be bothered by warm water immersion foot, and vice versa. The cause of this phenomenon was not determined.
Warm water immersion foot occurred after exposure to water varying in temperature from 15? to 32? C. Studies conducted in the United States showed that this condition appeared more quickly at higher water temperatures.90
Etiology.-The cause of warm water immersion foot syndrome appeared to be hyperhydration, or 'waterlogging,' of the plantar stratum
86(1) See footnote 73 (2), p. 102. (2) Douglas, J. S., Jr., and Eby, C. S.: Silicone for Immersion Foot Prophylaxis: Where and How Much to Use. Mil. Med. 137: 386-387, October 1972.
87(1) Report, Capt. Gustave T. Anderson, MC, USN, to Vice Adm. R. B. Brown, MC, USN, The Surgeon General, U.S. Navy, 10 Jan. 1966, subject: Immersion Foot. (2) Report, Capt. Gustave T. Anderson, MC, USN, to Commission on Cutaneous Disease, AFEB, 13 Feb. 1967, subject: Wet Foot Injury in Viet Nam.
88Buckels, Larry J., Gill, Kenneth A., Jr., and Anderson, Gustave T.: Prophylaxis of Warm-Water?Immersion Foot. J.A.M.A. 200: 681-683, 22 May 1967.
89(1) See footnote 81, p. 106. (2) Taplin, David, Zaias, Nardo, and Blank, Harvey: The Role of Temperature in Tropical Immersion Foot Syndrome. J.A.M.A. 202: 546-549, 6 Nov. 1967.90See footnote 89 (2).
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corneum.91 Biopsies showed thickening of the keratin layer, with no evidence of involvement of the underlying dermis.92 The condition appeared to bear no relationship to cold injury.
Clinical features.-Cases of warm water immersion foot occurred in foot soldiers who had spent from 1 to 3 days wading in paddy water during combat operations. Symptoms consisted of pain confined to the soles of the feet. The pain usually was described as a tingling or burning sensation, or a feeling of 'walking on rope.' In severe cases, the pain and tenderness became so marked that the man was no longer able to walk and hospitalization was required.
The physical findings were the same in every case; the changes varied only in degree. The soles of the feet were pale, thickened, and wrinkled so as to present a corrugated appearance (fig. 51). There was pain on weight bearing, particularly under the metatarsal heads, but the soles were not unusually tender to touch. The plantar surfaces were rigid, and the convolutions could not be altered by pressure from the hand.
91See footnotes 73 (2), p. 102; and 89 (2), p. 115.
92Gill, K. A., Jr.: Report of a Field Study on Silicone Ointments MDX-4-4056 and MDX-4-4078. U.S. Naval Medical Field Research Laboratory Report. Volume XVII, No. 16, December 1967.
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Symptoms quickly subsided after the feet were removed from water. Most patients were free of pain and discomfort within 24 hours of hospitalization. In the majority of cases, the soles had regained their preimmersion appearance within 24 to 48 hours. Complete recovery almost invariably occurred within 72 hours. Patients could be discharged directly to their units.
Diagnosis.-The diagnosis of warm water immersion foot was based on the characteristic history and findings. Differential diagnosis was not a problem since no other conditions were likely to be confused with this type of injury.
Prognosis and complications.-The prognosis in cases of warm water immersion foot was uniformly good once the feet were removed from water. Complications were infrequent and consisted of occasional fissuring beneath the toes when the injured stratum corneum began to dry.
Treatment.-Effective treatment consisted of keeping the patient off his feet and allowing the soles to dry for 24 to 72 hours. The duration of treatment required depended on the severity of the injury.
Prevention.-Warm water immersion foot could be prevented by allowing the feet to dry overnight before reimmersion93 or by applying silicone grease daily to the bottoms of the feet.94 However, each method of prevention had its drawbacks. Removal of boots and socks for 8 of each 24 hours to allow the feet to dry was seldom feasible, especially among infantry units in areas where dry ground of any type was a premium. Silicone ointment was disliked by the troops because it was messy, ruined their socks, and had to be applied at least once every 24 hours to be effective.
Erosion Injury (Wet Sock Abrasions)
History and military significance.-Erosion injury was first recognized and described as a distinct clinical entity during the Vietnam war.95 It consisted of superficial erosions of the dorsum of the foot occurring in troops after marches in wet, gritty terrain. Erosion injury occurred under much the same conditions as did immersion injuries and could be similarly disabling for periods as long as several days.
Etiology.-The etiology of erosion injury was not fully understood. As the name suggests, the disorder was believed to be related to constant rubbing of wet, grit-laden socks against the dorsum of the foot while walking. This concept was supported further by the fact that erosions were confined to areas under the boot and were especially prone to occur under pressure points.
Clinical features.-Erosion injuries appeared within 24 hours of ex?
93See footnote 89 (2), p. 115.
94See footnotes 81, p. 106; 86 (2) and 88, p. 115.
95Anderson, Gustave T.: Immersion Injuries. In Samitz, M. H., and Dana, Alan S., Jr.: Cutaneous Lesions of the Lower Extremities. Philadelphia: J. B. Lippincott Co., 1971, pp. 168-172.
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posure to wet, sandy terrain as multiple, red, superficial erosions of the skin of the dorsum of the foot and the ankle (figs. 52 and 53). Symptoms consisted of burning pain. Fresh lesions had the appearance of blister bases and were similarly tender. At times the discomfort was so severe that the affected soldier could no longer walk and had to be temporarily removed from combat duty. Often these erosions were noted in patients evacuated primarily because of immersion injury.
Diagnosis.-Both erosion injury (wet sock abrasions) and tropical immersion foot occurred in infantrymen after prolonged exposures to wet terrain; both affected the ankle and dorsum of the foot; and both tended
119
?to produce bilateral, symmetrical lesions. Despite these similarities, they could be differentiated by the fact that erosion injury was multifocal and left a denuded, glistening surface, whereas tropical immersion foot was characterized by diffuse erythema and edema covering the entire area under the boot except the soles.
Treatment.-Erosion injuries healed within a week if the patient was removed to a dry environment and footgear was not worn until the lesions had reepithelialized. Secondary bacterial infections were treated with antibiotics.
Pitted Keratolysis
History and military significance.-Pitted keratolysis was first described in a Ceylonese by Castellani in 1910 under the term 'keratoma plantare sulcatum.' Since then, there have been occasional reports in the literature on this condition, mostly concerning its possible etiology.96 Attention was focused on pitted keratolysis in connection with the foot problems that occurred among U.S. troops in Vietnam, but there was doubt as to whether it was potentially disabling or even symptomatic.97
96Zaias, Nardo, Taplin, David, and Rebell, Gerbert: Pitted Keratolysis. Arch. Dermat. 92: 151-154, August 1965.
97(1) Gill, Kenneth A., Jr., and Buckels, Larry J.: Pitted Keratolysis. Arch. Dermat. 98: 7-11, July 1968. (2) Lamberg, Stanford I.: Symptomatic Pitted Keratolysis. Arch. Dermat. 100: 10-11, July 1969.
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Epidemiology.-Pitted keratolysis originally was thought to be a disorder confined to populations in the Tropics; however, studies in military personnel in the United States showed that the incidence was no different in the Temperate Zone than in the Tropics.98
The incidence of pitted keratolysis was related to exposure of the feet to water: 58 percent of 52 experimental subjects developed pitted keratolysis after a 5-day exposure to swamp water.99 A survey has shown the condition to be strongly associated with hyperhidrosis of the feet.100
Etiology.-Several investigators have reported the presence of gram?positive, argyrophilic, filamentous micro-organisms in the craters of the pits in the plantar stratum corneum.101 ACorynebacterium species has been isolated from these pits, but Koch's postulates have not been fulfilled with regard to this organism.102 In a case reported from Africa, the organisms in the pits were identified by their morphology as Dermatophilus congolensis, the cause of a pustular eruption in animals known as dermatophilosis.103
Maceration of the plantar stratum corneum by constant exposure to water over several days appears to be an essential factor in pathogenesis.
Clinical features.-Pitted keratolysis usually is asymptomatic and appears in persons whose feet stay wet because of the nature of their occupation. From a distance, the feet appear to be dirty or stained (fig. 54). However, close inspection reveals the presence of multiple, shallow, sharply punched-out pits in the plantar stratum corneum. The pits usually range from 1 to 3 mm in diameter but may coalesce to form larger erosions in the keratin layer. The thick, calloused horny layers covering the weight-bearing surfaces-the heels, the balls of the feet, and the undersurfaces of the toes-are the areas most affected.
Symptomatic and even disabling cases of pitted keratolysis were reported from Vietnam; however, it was not clear whether the pain and disability were caused by friction and other traumata or by the keratolytic process itself. The sites of injury were reported to be reddened, thinned, tender, anhidrotic, and adjacent to typical pits. The lesions were said to disappear spontaneously within 2 to 4 days after the feet were removed from a moist environment.104
Treatment.-A variety of agents were used in treatment, including Whitfield's ointment and 40-percent formalin in Aquaphor. Although no formal clinical trials were carried out, the formalin and Aquaphor mixture appeared to be the most effective agent for patients in Vietnam.105
98See footnote 97 (1), p. 119.
99See footnote 97 (1), p. 119.
100See footnote 97 (1), p. 119.101See footnotes 96 and 97 (1), p. 119.
102See footnote 97 (1), p. 119.103Rubel, Lawrence R.: Pitted Keratolysis and Dermatophilus congolensis. Arch. Dermat. 105: 584-586, April 1972.
104See footnote 97 (1) and (2), p. 119.
105See footnote 97 (2), p. 119.
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DISEASES OF THE SWEAT GLANDS, SEBACEOUS GLANDS, AND HAIR FOLLICLES
Noninfectious dermatoses involving the sweat glands and pilosebaceous apparatus of the skin produced a great deal of morbidity among U.S. military personnel in Vietnam. Next to bacterial and fungal infections, they were the most common dermatologic cause of outpatient visits, hospitalization, and disability. The most important of these entities were miliaria (prickly heat), dyshidrosis, acne, and pseudofolliculitis barbae. Unlike the infectious dermatoses, they did not have a special predilection for combat troops. Instead, they were more evenly distributed throughout the entire troop population. In addition, they were generally not as amenable to prevention and treatment as were infections.
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Miliaria (Prickly Heat)
History and military significance.-'Heat rashes' have been known for hundreds of years. The relationship between these eruptions and occlusion of the outlets of the eccrine sweat glands was first established in the late 19th century.
Miliaria was one of the most frequently encountered skin disorders among American troops in the Tropics during World War II, and it was a well-known but lesser problem in troop populations in the United States.106 At that time some observers considered it to be caused either by Candida infection or by salt depletion.107 Treatment modalities were not satisfactory. Research carried out by the British during and after the war demonstrated a relationship between poral closure caused by miliaria and the development of various injury syndromes.108
In Vietnam, miliaria was almost never a direct cause of disability in troops. Nonetheless, some physicians thought that it predisposed men to fatigue and heat exhaustion. It was a major cause of outpatient visits and referrals to dermatologists. The latter had no specific, effective therapies to offer except the recommendation to 'stay cool.'
Epidemiology.-Although exact figures were not available, the epidemiology of miliaria in Vietnam was clear cut. In the northern (I Corps) area of South Vietnam, where ambient temperature had marked seasonal changes, the incidence of clinically significant miliaria in soldiers rose dramatically after temperatures began exceeding 38? C.109 Cooks were at greatest risk of developing severe, widespread miliaria because they were forced to work in small, poorly ventilated rooms or tents where the temperature and humidity were extraordinarily high.110 Reversal of the clinical manifestations of this disorder occurred promptly after the affected individuals were placed in a cool environment. It was immaterial whether this occurred by virtue of a change in season, a change in occupation, or the provision of improved ventilation. Why some men were more susceptible than others was not determined.
Etiology.-Miliaria is caused by occlusion and rupture of eccrine sweat ducts.111 Contributing factors are friction, heat stress, and high humidity. All these factors were present in abundance in Vietnam.
Clinical features.-The most common clinical form of miliaria in Vietnam was miliaria rubra, more commonly known as prickly heat. Examina?
106See footnote 11, p. 62.
107(1) See footnote 11, p. 62. (2) Smith, E. C.: Prickly Heat: Its Aetiology and Pathology. Tr. Roy. Soc. Trop. Med. & Hyg, 20: 344-351, January 1927.
108O'Brien, J. P.: A Study of Miliaria Rubra, Tropical Anhidrosis and Anhidrotic Asthenia. Brit. J. Dermat. & Syph. 59: 125-158, April-May 1947.
109Jones, Henry E.: Vietnam Dermatology. [Unpublished account of Major Jones' professional experiences in Vietnam, 1970-71.]
110See footnote 66, p. 98.
111See footnote 108.
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tion of affected areas of skin revealed a fine erythematous, papular, periportal eruption which was most frequently located in the flexion creases and on the trunk (fig. 55). The eruption caused considerable discomfort but rarely was disabling. Characteristically, the face, palms, and soles were never affected. The condition occurred in those who were heat-acclimatized and tanned as well as in those who were not.
A second and more serious form of miliaria-miliaria profunda-was seen much less frequently and usually developed in cases of severe and prolonged miliaria rubra. It presented as noninflamed nodules on the trunk and extremities and, in most cases, was nonpruritic and inapparent on examination. It was considered a truly debilitating disease and the cause of 'tropical anhidrotic asthenia,' a potentially fatal disorder. The latter presented as relative anhidrosis (often with marked secondary hyperhidrosis of the face) associated with hyperthermia and shock. Patients with this disorder were hospitalized in an air-conditioned ward, after which their temperatures returned to normal within 24 to 48 hours. Most of these patients could not safely be returned to duty and required transfer to a country with a cooler climate.
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Treatment.-In Vietnam, as in World War II, no mode of treatment of miliaria was satisfactory. A number of remedies were tried, all with various testimonials to their success. Among those most commonly recommended and used were oral tetracycline; high doses of ascorbic acid (vitamin C); steroid creams; and a shake lotion containing menthol, camphor, salicylic acid, and isopropyl alcohol.112 Only for vitamin C was there evidence of efficacy based on a well-conducted trial.113 However, clinical experience with vitamin C was generally disappointing.
Prevention.-Ascorbic acid was administered as a prophylactic agent to those who were prone to developing prickly heat. As in treatment, the results were not impressive. In the few instances where it was possible, placement of susceptible persons in a cool environment (such as an air-conditioned room or office) for 6 to 8 hours a day was remarkably effective in preventing recurrences. No broadly applicable preventive measures were found to be effective.
Dyshidrosis
Military significance.-Dyshidrosis eczema of the hands and feet was commonly seen by dermatologists in Vietnam, and it was high on the list of dermatological causes of evacuation from the theater. Much of its visibility was attributable to the fact that nearly all cases were referred to dermatologists for treatment. Affected individuals became disabled because of the location of the lesions on the palms and soles and because the lesions tended to become secondarily infected. The military importance of dyshidrosis was not great because it was uncommon.
Etiology.-Dyshidrosis was postulated to be analogous to miliaria and to be caused by plugging and rupturing of the eccrine sweat glands of the palms and soles;114 however, this has not been convincingly demonstrated. Dermatologists in Vietnam believed that preexisting cases of dyshidrosis became worse in the hot, humid climate, and that factors such as extreme heat and nervous tension were responsible for producing new cases of this disease.115
Clinical features.-Dyshidrosis appeared as a vesiculobullous eruption involving the sides of the fingers, the palms of the hands, and occasionally the soles of the feet. The blisters frequently ruptured, whereupon they almost inevitably became secondarily infected. Recurrences following treatment were common. Such cases required medical evacuation.
112(1) See footnote 43, p. 87. (2) Dermatologic Problems. USARV Med. Bull. (USARV Pam 40-25), January-February 1971, pp. 31-34.
113Hindson, T. C.: Ascorbic Acid for Prickly Heat. Lancet 1: 1347-1348, 22 June 1968.114See footnote 66, p. 98.
115(1) Harman, Louis E., Jr.: Skin Diseases in United States Military Personnel Serving in Vietnam. In The Skin (Elson B. Helwig and F. K. Mostofi, editors). Baltimore: Williams & Wilkins Co., 1971, pp. 423-434. (2) See footnote 66, p. 98.
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Treatment.-Ruptured blisters that had become secondarily infected were treated with wet soaks and systemic antibiotics. Parenteral and topical steroid preparations were administered for treatment of the underlying disease. The patient was advised not to use his hands (or feet) until the lesions had healed. Response to therapy was seldom satisfactory; dermatologists considered dyshidrosis to be one of the most difficult disorders to treat.
Acne
History and military significance.-Acne has long accounted for a significant proportion of outpatient visits to military dermatology clinics, both in the United States and overseas, but otherwise has not been considered to be of major military importance.
Under Army regulations in effect at the time of the Vietnam conflict, persons with severe acne could be refused induction into military service or could be mandatorily separated from the service.116 The degree of enforcement of these regulations varied from place to place, and consequently a number of people with severe acne were on active duty. Military dermatologists who saw men with cystic acne involving the back, neck, and chest customarily awarded 'profiles,' an administrative device that kept these men from being sent to duty stations in hot, humid areas such as Vietnam.
The problem of severe cystic ('tropical') acne arising in the course of service in the Tropics was first clearly recognized during World War II.117 A small number of American military personnel stationed in the Southwest Pacific Area and in the China-Burma-India Theater developed severe cystic acneiform lesions on the nape, back, and chest. These lesions were painful and interfered with the performance of duty, especially if the affected soldier was required to carry a pack. No form of therapy was effective; medical evacuation from the Tropics was required. The lesions involuted spontaneously within weeks after the patient had returned to a temperate climate. The incidence of severe cystic acne was never determined, but there was nothing to suggest that the loss of manpower arising from this disorder was significant.
With the advent of the war in Vietnam, 'tropical acne' quickly assumed prominence because an early report indicated that it was the leading dermatologic cause of evacuation from Vietnam.118 This prominence was unjustified because the total number of evacuations for all dermatologic causes was small.119 As in World War II, there was no evidence that losses
116Army Regulation (AR) No. 40-501, Standards of Medical Fitness, December 1960.
117Sulzberger, Marion B., Addenbrooke, Edward F., Joyce, Stanley J,, Greenberg, Solomon, and Mack, Arthur G.: Tropical Acne. U.S. Naval Med. Bull. 46: 1178-1184, August 1946.
118See footnote 115 (1), p. 124.119See footnote 68, p. 100.
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of personnel because of tropical acne had a significant impact on troop strength or fighting capability.
Epidemiology.-The occurrence of tropical acne bears a clear relationship to exposure to a tropical climate. As with other forms of acne, black soldiers were much less susceptible than were white soldiers.120
During the Vietnam conflict, there was little general agreement on the epidemiologic features of tropical acne other than the points just mentioned. Some dermatologists felt that exposure to oil and grease in motor pools was significant, whereas others thought that cooks and kitchen personnel were at special risk. Most seemed to feel that persons with significant preexisting acne were more likely to develop tropical acne than were those without preexisting disease.
The first epidemiologic study of tropical acne was carried out in Vietnam by a U.S. Navy medical officer, Lt. Cdr. Stanford I. Lamberg, MC.121 Commander Lamberg examined 1,800 marines just before their departure for Vietnam and was able to obtain followup examinations on 156 (52 percent) of 302 men selected as cases or controls. The findings indicated that most of the men with preexisting acne on the back either stayed the same or improved during a 4- to 6-month period in Vietnam. There was a suggestion that preexisting acne became worse more often than nonexistent acne became apparent, but the difference was not statistically significant.
No cases of significant acne of the back were seen in black marines either at the initial screening examination or during followup. There was little to indicate that factors such as cleanliness, diet, and exposure to sunlight altered the men's susceptibility to tropical acne.
Etiology.-The underlying etiology of cystic acne in Vietnam was unknown; however, most dermatologists believed that it was simply severe conglobate acne developing in areas other than the face under the influence of tropical environmental conditions.
Clinical features.-The distinguishing features of the cases of tropical acne seen in Vietnam were (1) usually seen in an older age group than those with ordinary facial acne; (2) primarily involved the nape of the neck, the back, chest, buttocks, shoulders, and thighs; (3) characterized by the presence of large multilocular cysts and nodules which were inordinately painful and tender; and (4) not necessarily associated with preexistent acne. Large, adjacent cysts often developed intercommunicating channels (fig. 56). Ruptured cysts extruded a foul-smelling, cheesy, grayish-yellow material that yielded Propionibacterium [Corynebacterium] acnes and a number of other bacteria on culture.
Tropical acne was a painful, unsightly, unpleasant experience for any affected individual. Men with field duty suffered most because the trauma inflicted by wearing packs and web gear further inflamed the lesions. Re?
120Lamberg, Stanford I.: The Course of Acne Vulgaris in Military Personnel Stationed in Southeast Asia. Cutis 7: 655-660, June 1971.
121See footnote 120.
127
128
sponse to treatment was unsatisfactory. Permanent scarring resulted from severe cases (figs. 57 and 58).
Treatment.-The recommended therapeutic regimen consisted of (1) removal from a dirty (field) or oily (motor pool) environment; (2) frequent cleansing using an antibacterial soap; (3) topical applications of a peeling agent such as Fostex, a sulfur-containing lotion; and (4) oral tetracycline to alter the composition of the sebum.122 This regimen was usually ineffective unless carried out on a long term basis in an air?conditioned hospital ward. The success of therapy was probably attributable more to the cool, clean environment than to the rest of the regimen. The majority of cases were evacuated from Vietnam because of inadequate
122Dermatologic Problems. USARV Med. Bull. (USARV Pam 40-19), January-February 1970, pp. 29-32.
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response to treatment. Cases evacuated to Japan or the United States healed rapidly, even in the absence of treatment.123
Pseudofolliculitis Barbae
Military significance.-The military importance of pseudofolliculitis barbae among the troop population in Vietnam stemmed from a variety of medical and social factors. One of the most important was the inability to control the condition by simple, readily available means. Another factor
123Lewis, C. W., Griffin, T. B., Henning, D. R., and Akers, W. A.: Tropical Acne: Clinical and Laboratory Investigations, Report No. 16, Dermatology Research Division, Letterman Army Institute of Research, 1 May 1973.
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was the confrontations that developed when an affected soldier grew a beard to overcome the problem. Beards were specifically proscribed by Army regulations, and physicians were directed not to award 'profiles' authorizing patients to grow beards.124 Nevertheless, physicians often did so. And when they did not, the affected individual sometimes grew a beard on his own initiative. This activity was generally interpreted by commanders as a defiance of their authority and a breach of discipline.
The situation was further aggravated by the factor of race. Those who were susceptible (that is, black soldiers) sometimes accused those in authority of racial bias whenever the conflict between growing beards and maintaining a neat military appearance arose. Conversely, those in authority sometimes interpreted these accusations as a deliberate, racially motivated attempt to create trouble. The ability of some black soldiers to control the pseudofolliculitis with relative ease served only to heighten the air of suspicion and mistrust. Thus a tense social climate elevated a trivial affliction of the skin to a disease of considerable importance.
Etiology.-Pseudofolliculitis consists of papulopustular lesions caused by ingrown hairs. Black soldiers are particularly susceptible because the shape of the hair (oval in cross section) is such that the hair shaft tends to curl back on itself as it grows out of the follicle. Shaving with a safety razor creates conditions that favor the development of pseudofolliculitis, whereas use of a chemical depilatory does not.
In Vietnam, depilatories were not carried in medical supply channels, nor were they stocked in the exchanges. The tropical climate and unhygienic conditions in themselves had little effect on the condition.
Clinical features.-Typical pseudofolliculitis barbae presented as a papulopustular eruption in the bearded region of the face and neck of black soldiers (fig. 59). The lesions were concentrated in the neck area. Impetigo occasionally developed as a secondary infection.
Treatment.-The most common form of treatment was to allow the beard to grow for 3 or 4 weeks so that the pustules could heal. Topical steroid and antibiotic preparations were frequently prescribed but were of little use.125
Prevention.-The most important factor in prevention was education of the patient about the proper means of shaving. Patients were instructed to use chemical depilatories or to shave with a safety razor set at the highest setting. Success in prevention seemed to depend to a large extent on the attitude and motivation of the patient.
PARASITE INFESTATIONS AND INFECTIONS
Skin lesions caused by parasites were rare in U.S. Army personnel in Vietnam. Leech bites and blister beetle burns occurred sporadically and
124See footnote 122, p. 128.
125See footnote 122, p. 128.
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attracted attention primarily because of the unusual nature of their manifestations. Scabies was common among the civilian population but did not affect Americans. The few cases of cutaneous leishmaniasis that appeared had all been acquired during jungle training in Panama.126 Cutaneous larva migrans (creeping eruption) was seen occasionally, particularly among soldiers who frequented beach areas, and was probably caused by dog hookworm larvae.127 Small outbreaks of schistosome dermatitis (swimmer's itch) occurred at infrequent intervals among infantrymen and sometimes could be traced to a single exposure to water, as when fording a stream.128 The schistosomes involved were probably of avian or bovine origin, since human schistosomiasis was not present in Vietnam.
Leech Infestation (Hirudiniasis)
History and military significance.-Leeches have been known and used by physicians since antiquity. Until a century ago, they were commonly employed in medical treatment. During the past century, a number of
126See footnote 66, p. 98.
127See footnote 66, p. 98.
128Allen, Alfred M., Taplin, David, Legters, Llewellyn J., and Ferguson, James A.: Schistosomes in Vietnam, Lancet 1: 1175-1176, 8 June 1974.
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isolated reports have appeared in the medical literature concerning leech infestation in natives of developing countries and in travelers to remote jungle areas.129 Native children have been known to die of multiple leech infestation of the throat acquired by drinking contaminated water, and travelers on expeditions in southern and eastern Asia have been plagued by multiple leech attacks after walking or swimming in infested areas.
Leech infestation escaped mention as a medical problem in American troops during World War II, but occasional cases undoubtedly occurred among men in the Tropics. In Vietnam, leeches attained a prominence out of proportion to their true significance because of the wide circulation of exaggerated stories concerning the frequency of attacks and the results of infestation. Of particular concern was the possibility, however remote, that leeches would enter the urethral meatus and become engorged while within the penile urethra. The adverse effects on the morale of field troops created by fear of leech infestation were far more significant than any physical effects resulting from the condition.
Epidemiology.-Medically important leeches were found both in fresh water and on land in Vietnam. In lowland areas, such as the Mekong Delta, aquatic leeches were found in scattered areas. Certain swamps and paddies developed a reputation because of the large number of leeches they harbored. In heavily jungled areas, terrestrial leeches were common along trails on wet vegetation.
Leech infestation in soldiers was largely a function of exposure to areas where leeches were abundant. These exposures were most frequent in infantrymen.
Etiology.-A number of water and land leeches caused hirudiniasis in Vietnam. They either attached themselves at the moment of contact with an exposed skin surface or insinuated themselves through several layers of clothing to reach the skin. After attachment to the host, the leeches used the sharp cutting plates in their mouths to cut a characteristic triradiate hole in the skin to suck blood (fig. 60). Heparinlike substances in the leeches' saliva prevented clotting during engorgement. The anticoagulant effect lasted for several hours after the leech had dropped from the skin.
Clinical features.-In most instances, the leech bite was painless and was noticed only when the soldier happened to see the leech or when his attention was drawn to a persistently oozing small wound on his skin. The usual sites of involvement were the legs and arms. Mild itching around the area of the bite was an occasional symptom.
Other than the disgust caused by finding an engorged leech on the skin, the principal problem caused by leeches was that the area of the bite often became secondarily infected by bacteria. Leech bites thus served as precursors of streptococcal ecthyma.130
129Keegan, H. L., Toshioka, S., and Suzuki, H.: Blood-Sucking Asian Leeches of Families Hirudidae and Haemadipsidae. 406th Medical Laboratory Special Report, U.S. Army Medical Command, Japan, July 1968.
130See footnote 45, p. 87.
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Infestation of the penile urethra was much talked about but occurred rarely if at all.
Bite areas healed rapidly if the site did not become secondarily infected.
Treatment.-Leeches that were attached to the skin could be removed easily by touching them with a lighted cigarette or a drop of insect repellent or by pouring salt on their bodies (fig. 61). Application of a styptic pencil controlled bleeding from the bite wound. Secondary infections were treated with antibiotics.
Prevention.-When entering bodies of water known to be leech-infested, tucking pants legs into boots and snugly lacing the boots afterwards
134
were partially effective as a preventive measure. The insect repellent DEET (diethyltoluamide) in a liquid base was effective when applied to the skin. However, the protection seldom lasted more than 30 minutes if the soldier was sweating profusely or was in water. A lanolin-based leech repellent was field tested and found to persist longer on the skin than did the liquid-based preparation, but it was never distributed through supply channels.131
Blister Beetle Dermatitis
Military significance.-Occasional cases of blister beetle dermatitis occurred among field troops who, while lying on the ground, came in contact with the beetle. Severe reactions could be disabling for several days. The total amount of disability from this source was slight.
131(1) Report, Lt. Col. Foster H. Taft, Jr., MC, Surgeon, U.S. 9th Infantry Division, to Surgeon, USARV, 11 Jan. 1968. subject: Leech Repellent in Lanolin-Requirements and Experience. (2) Taft, Foster H., Jr.: Preliminary Experiences With a Long Acting Leech Repellent. USARV Med. Bull. (USARV Pam 40-7), January-February 1968, p. 56.
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Etiology.-The burns were caused by contact with beetles whose bodies contained cantharidin or a related blistering agent. The species of beetles responsible for this form of dermatitis in Vietnam were not identified but presumably belonged to the families Meloidae or Staphylinidae.132
Clinical features.-Soldiers with blister beetle dermatitis first noticed an itching or burning sensation on the exposed skin surface that had come into contact with the beetle. Usually this happened at night when the men were lying on the ground to sleep. Consequently, the beetle was almost never seen. Within several hours a large blister developed at the site of contact. Upon rupture of the blister, the underlying skin surface had the appearance of a second-degree burn (fig. 62). Reepithelialization was slow even if secondary infection did not occur.
Diagnosis.-Bullous eruptions occurred in response to a variety of stimuli; however, those caused by vesicating beetles could be differentiated by the history of itching and burning before appearance of the blister, the
132Gahan, James B., and Smith, Carroll, N.: Class Insecta (Hexapoda), In A Manual of Tropical Medicine (George W. Hunter, William W. Frye, and J. Clyde Swartzwelder, editors). 4th edition, Philadelphia: W. B. Saunders Co., 1966, pp. 730-731.
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location of the lesions on skin surfaces that had been exposed to the ground, and the linear configuration of the lesions.
Treatment.-Treatment consisted of draining the bullae and dressing the lesions to prevent contamination and secondary infection. The presence of large, raw, sensitive skin surfaces usually precluded return to full duty until some degree of reepithelialization had taken place.
CONTACT DERMATITIS
As in World War II, contact dermatitis was infrequent among troops in Vietnam. The cases that did arise were attributable to a variety of contact irritants or allergens, and, with possibly one exception, no substance was prominent. Of those contactants that could be positively identified as the offending substances, plants, lighter fluid, solvents, topical medications (such as Vioform and Furacin), and the insect repellent DEET (diethyltoluamide) were most commonly mentioned by dermatologists.133 DEET was of particular interest because it had not previously been suspected of being capable of causing a significant skin reaction of the type that occurred.
Dermatitis caused by overtreatment of underlying dermatoses was a common problem in World War II, but was uncommon during the Vietnam conflict.134 This favorable difference was attributed to the advent during the interwar years of antibiotics and anti-inflammatory corticosteroids, which replaced the harsh, sensitizing topical remedies that had been used in World War II.
History and military significance.-Diethyltoluamide, a topical insect repellent, was first used on a large scale in military forces during the Vietnam conflict. It was virtually nonirritating if contact with the mucous membranes was avoided. But, during the course of the war, a peculiar form of dermatitis occurred that later would be linked to the use of DEET. Dermatologists treated a number of patients with bullous eruptions in the antecubital fossae and usually attributed the lesions to contact with a vesicating beetle of the genus Paederus.
Commander Lamberg135 suspected that bullous lesions were in fact caused by a reaction to DEET and carried out studies to confirm the hypothesis. Although the number of these patients was not great, the pain, disability, and permanent scarring that occurred indicate that all future users of DEET should be made aware of the hazard.
133(1) See footnotes 66, p. 98; and 109, p. 122. (2) Lamberg, Stanford I., and Mulrennan, John A., Jr.: Bullous Reaction to Diethyl Toluamide (DEET) Resembling a Blistering Insect Eruption. Arch. Dermat. 100: 582-586, November 1969.
134(1) Pillsbury, Donald M., and Livingood, Clarence S.: Experiences in Military Dermatology. Arch. Dermat. & Syph. 55: 441-462, April 1947. (2) See footnote 2, p. 60.
135See footnote 133 (2), p. 60.
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Epidemiology.-The reactions attributed to DEET were seen in the same type of patient who might present with a blister beetle burn-infantrymen and sentries whose duties required them to sleep in the field during the night.
Etiology.-Experiments with volunteers indicated that heavy topical applications of DEET to the antecubital or popliteal fossae could cause severe blistering in a high proportion of normal men. The reactions could not be attributed to an allergic response, and they could not be elicited in any other area of the body. Although the mechanism of injury could not be determined, it was presumed that DEET had primary irritant properties. Reactions to DEET occurred independently of commercial source, concentration, and type of container employed.
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Clinical features.-Reactions thought to be caused by DEET were always located in the antecubital fossae. The lesions began as reddened, tender areas which evolved over a 24-hour period into multiple small bullae (fig. 63). Occasional cases were bilateral in distribution. The bullae remained intact for up to 3 days and then ruptured, leaving an eroded, purulent base (fig. 64). Most patients were unable to extend their arms because of the pain, and the lesions were therefore disabling. Most patients developed permanent scarring (fig. 65).
All patients gave a history of having slept in the field the night before the eruption began and all had used DEET. None could recall having had an insect on his arms, However, other men in the same area developed typical linear-shaped bullae on exposed surfaces, and Paederus beetles were known to exist in the area.
Treatment.-No specific therapeutic measures were available. Compresses and steroid creams were applied to provide symptomatic relief.
Prevention.-The findings of the Navy investigators were not con?firmed in time to prepare and disseminate a warning to American forces in Vietnam concerning the skin reactions to DEET. Prevention presumably could be accomplished by avoiding the antecubital area when applying DEET; however, this point was not firmly established.
