Kenneth C. Hyams

Diarrheal Disease during Operation Desert Shield

BACKGROUND Under combat conditions infectious disease can become a major threat to military forces. During Operation Desert Shield, there were numerous outbreaks of diarrhea among the U.S. forces. To evaluate the causes of and risk factors for diarrheal disease, we collected clinical and epidemiologic data from U.S. troops stationed in northeastern Saudi Arabia. METHODS Between September and December 1990, stool cultures for enteric pathogens were obtained from 432 military personnel who presented with diarrhea, cramps, vomiting, or hematochezia. In addition, a questionnaire was administered to 2022 soldiers in U.S. military units located in various regions of Saudi Arabia. RESULTS A bacterial enteric pathogen was identified in 49.5 percent of the troops with gastroenteritis. Enterotoxigenic Escherichia coli and Shigella sonnei were the most common bacterial pathogens. Of 125 E. coli infections, 39 percent were resistant to trimethoprim-sulfamethoxazole, 63 percent to tetracycline, and 48 percent to ampicillin. Of 113 shigella infections, 85 percent were resistant to trimethoprim-sulfamethoxazole, 68 percent to tetracycline, and 21 percent to ampicillin. All bacterial isolates were sensitive to norfloxacin and ciprofloxacin. After an average of two months in Saudi Arabia, 57 percent of the surveyed troops had at least one episode of diarrhea, and 20 percent reported that they were temporarily unable to carry out their duties because of diarrheal symptoms. Vomiting was infrequently reported as a primary symptom, but of 11 military personnel in whom vomiting was a major symptom, 9 (82 percent) had serologic evidence of infection with the Norwalk virus. CONCLUSIONS Gastroenteritis caused by enterotoxigenic E. coli and shigella resistant to a number of drugs was a major problem that frequently interfered with the duties of U.S. troops during Operation Desert Shield.

Post-combat syndromes from the Boer war to the Gulf war: a cluster analysis of their nature and attribution

Abstract Objectives: To discover whether post-combat syndromes have existed after modern wars and what relation they bear to each other. Design: Review of medical and military records of servicemen and cluster analysis of symptoms. Data sources: Records for 1856 veterans randomly selected from war pension files awarded from 1872 and from the Medical Assessment Programme for Gulf war veterans. Main outcome measures: Characteristic patterns of symptom clusters and their relation to dependent variables including war, diagnosis, predisposing physical illness, and exposure to combat; and servicemens changing attributions for post-combat disorders. Results: Three varieties of post-combat disorder were identified — a debility syndrome (associated with the 19th and early 20th centuries), somatic syndrome (related primarily to the first world war), and a neuropsychiatric syndrome (associated with the second world war and the Gulf conflict). The era in which the war occurred was overwhelmingly the best predictor of cluster membership. Conclusions: All modern wars have been associated with a syndrome characterised by unexplained medical symptoms. The form that these assume, the terms used to describe them, and the explanations offered by servicemen and doctors seem to be influenced by advances in medical science, changes in the nature of warfare, and underlying cultural forces.

The risk of measles, mumps, and varicella among young adults: a serosurvey of US Navy and Marine Corps recruits.

OBJECTIVES To assess the risk of epidemic transmission and to guide immunization policy, the seroprevalence of antibody to measles, mumps, and varicella was determined in a group of young adults. METHODS A cross-sectional study of 1533 US Navy and Marine Corps recruits was conducted in June 1989. Antibody status was determined with commercially available enzyme-linked immunosorbent assays. RESULTS Direct sex and race adjustment to the 15- to 29-year-old US population resulted in seronegativity rates of 17.8% for measles, 12.3% for mumps, and 6.7% for varicella. Measles and mumps seronegativity rates were higher among Whites whereas varicella seronegativity was higher among non-Whites. Recruits enlisting from outside the 50 US states, especially those from island territories, were more likely to lack varicella antibody. The sensitivity of a positive history of vaccination or disease in predicting antibody status was less than 90% for all diseases. CONCLUSIONS These results suggest a continued potential for epidemics, especially of measles, and the need for mandatory immunization policies. Immigrants to the United States, especially those from island territories, may be a high-risk group that could benefit from varicella vaccination.

Endemic Infectious Diseases of Afghanistan

The current crisis in Afghanistan has resulted in an influx of Western military personnel, peacekeepers, humanitarian workers, and journalists. At the same time, unprecedented numbers of internally displaced persons and refugees have overwhelmed much of the already fragile infrastructure, setting the stage for outbreaks of infectious diseases among both foreigners and local populations. This review surveys the literature concerning the infectious diseases of Afghanistan and south-central Asia, with particular emphasis on diseases not typically seen in the Western world.

Norwalk-like virus infection in military forces : Epidemic potential, sporadic disease, and the future direction of prevention and control efforts

The impact of Norwalk-like virus (NLV) infection on military forces is evaluated in this report. NLVs were a major cause of both outbreaks and sporadic disease among crowded US ground troops in the 1991 war with Iraq. NLVs also have been found to be a cause of acute gastroenteritis in other ground and shipboard deployments. Four large outbreaks of acute gastroenteritis were investigated aboard US Navy aircraft carriers between 1992 and 1997. In these outbreaks, NLVs were identified as the probable cause, and crowding was a major risk factor for transmission. An evaluation of a routine shipboard deployment also suggests that NLVs cause sporadic gastroenteritis. These data indicate that NLV infection is a major cause of acute morbidity in military forces. Because of the limitations of available prevention and control methods, development of a vaccine against these viruses may be the best solution in the military environment.

The unique riverine ecology of hepatitis E virus transmission in South-East Asia

The ecology of hepatitis E virus (HEV) transmission in South-East Asia was assessed from a review of 6 published and 3 unpublished NAMRU-2 reports of hepatitis outbreak investigations, cross-sectional prevalence studies, and hospital-based case-control studies. Findings from Indonesia and Viet Nam show epidemic foci centred in jungle, riverine environments. In contrast, few cases of acute, clinical hepatitis from cities in Indonesia, Viet Nam and Laos could be attributed to HEV. When communities in Indonesia were grouped into areas of low (< 40%), medium (40-60%), and high (> 60%) prevalence of anti-HEV antibodies, uses of river water for drinking and cooking, personal washing, and human excreta disposal were all significantly associated with high prevalence of infection. Conversely, boiling of river drinking water was negatively associated with higher prevalence (P < 0.01). The protective value of boiling river water was also shown in sporadic HEV transmission in Indonesia and in epidemic and sporadic spread in Viet Nam. Evidence from Indonesia indicated that the decreased dilution of HEV in river water due to unusually dry weather contributed to risk of epidemic HEV transmission. But river flooding conditions and contamination added to the risk of HEV infection in Viet Nam. These findings attest to a unique combination of ecological and environmental conditions predisposing to epidemic HEV spread in South-East Asia.

Risk Factors for Sexually-Transmitted Diseases Among Deployed U.S. Military Personnel

BACKGROUND AND OBJECTIVES Information regarding risk factors for STD transmission is needed to assist in designing and evaluating prevention and control programs for US military populations. GOAL OF THIS STUDY To obtain STD risk factor data among deployed U.S. military personnel. STUDY DESIGN A questionnaire survey was administered to military personnel deployed aboard ship for six months to South America, West Africa, and the Mediterranean during 1989-1991. RESULTS Among 1,744 male subjects (mean age, 23 years; 71% white; 96% enlisted), 49% reported prior sexual contact with a prostitute and 22% reported a history of a STD before deployment. During the subsequent six-month deployment, 42% reported sexual contact with a prostitute, 10% reported inconsistent use of condoms, and 10% acquired a new STD. By logistic regression analysis, sexual contact with a prostitute during deployment was independently associated with young age, nonwhite race/ethnicity, and being unmarried or divorced; inconsistent use of condoms was associated with Hispanic race/ethnicity. CONCLUSION These data indicate that deployed U.S. military personnel frequently engage in high-risk sexual behavior and that there is a continued need for comprehensive and culturally-sensitive STD prevention programs.

Hepatitis B and C in Juba, southern Sudan: results of a serosurvey

To compare the epidemiology of hepatitis B virus (HBV) with hepatitis C virus (HCV) in a southern Sudanese population, 666 out-patients attending 6 public clinics in the city of Juba were enrolled in a serosurvey. The average age of subjects was 16 years; 54% were female. Of the 651 samples tested for hepatitis B markers, HBsAg was found in 26% and anti-HBc in 67%. In contrast, only 21 (3%) of the 666 samples were positive for anti-HCV using a second generation immunoblot assay (RIBA-2). Seventeen (81%) of the 21 anti-HCV-positive subjects were positive for anti-HBc, compared to 66% (418/630) of subjects negative for anti-HCV (P = 0.07). None of the anti-HCV-positive subjects reported receiving a prior blood transfusion and only 5 subjects reported a history of jaundice. Nine of the 21 (43%) anti-HCV-positive subjects reported a history of scarification, compared to 23% (148/645) of anti-HCV-negative subjects (P = 0.01). Hepatitis B infection was also associated with scarification by univariate analysis. However, after adjustment for age a history of scarification was not significantly associated with hepatitis C infection, but it was with HBV infection (odds ratio = 1.5, 95% CI 1.0-2.5; P = 0.05). The findings of this study indicate that HCV infection is not highly endemic in this population and that the epidemiology of HCV differs from that of HBV.

Hyperendemic Streptococcus pyogenes infection despite prophylaxis with penicillin G benzathine.

BACKGROUND In closely confined populations, in which epidemics of Streptococcus pyogenes infection are common, penicillin G benzathine has long been used prophylactically to reduce morbidity from this pathogen. We report on our investigations of the effectiveness of penicillin G benzathine prophylaxis at a military recruit camp. METHODS We prospectively studied the rates of pharyngeal colonization and infection by S. pyogenes among 736 male U.S. Marine Corps recruits from January through March 1989. Throat swabs for culture, clinical data, and questionnaire data were obtained during six examinations at intervals of two weeks. Serum samples obtained before training, after training, and from acutely ill recruits were analyzed with use of an antistreptolysin O microtitration technique. RESULTS Although 93 percent of the recruits received prophylaxis with two intramuscular injections of 1.2 million units of penicillin G benzathine each (administered 30 to 39 days apart), 33 percent of the recruits were colonized by S. pyogenes, and 42 percent had infection (as defined by a two-dilution increase in the antistreptolysin O titer). Thirty-seven percent of 265 recruits who reported a sore throat and were infected with S. pyogenes did not seek medical attention. The recruits who were allergic to penicillin (7 percent of the total), who received no prophylaxis, were more likely to be colonized; an increased risk of colonization and infection among the nonallergic recruits was associated with the presence of a higher percentage of allergic recruits in the platoon. After the study was completed, all recruits who were allergic to penicillin were prescribed 250 mg of oral erythromycin twice daily (a total daily dose of 500 mg) for 60 days. Subsequently, the average weekly rate of clinically evident S. pyogenes pharyngitis fell by more than 75 percent. CONCLUSIONS If the prevention of S. pyogenes infection is to be effective in closely confined populations such as military recruits, prophylactic antibiotics must be administered to all members of the population. Exempting those who are allergic to penicillin may create a bacterial reservoir from which infection can be transmitted to nonallergic members of the population.

Managing future Gulf War Syndromes: international lessons and new models of care

After the 1991 Gulf War, veterans of the conflict from the United States, United Kingdom, Canada, Australia and other nations described chronic idiopathic symptoms that became popularly known as ‘Gulf War Syndrome’. Nearly 15 years later, some 250 million dollars in United States medical research has failed to confirm a novel war-related syndrome and controversy over the existence and causes of idiopathic physical symptoms has persisted. Wartime exposures implicated as possible causes of subsequent symptoms include oil well fire smoke, infectious diseases, vaccines, chemical and biological warfare agents, depleted uranium munitions and post-traumatic stress disorder. Recent historical analyses have identified controversial idiopathic symptom syndromes associated with nearly every modern war, suggesting that war typically sets into motion interrelated physical, emotional and fiscal consequences for veterans and for society. We anticipate future controversial war syndromes and maintain that a population-based approach to care can mitigate their impact. This paper delineates essential features of the model, describes its public health and scientific underpinnings and details how several countries are trying to implement it. With troops returning from combat in Afghanistan, Iraq and elsewhere, the model is already getting put to the test.