Non-battle injury casualties during the Persian Gulf War and other deployments.

OBJECTIVE: To review injury occurrence and to evaluate various injury surveillance systems used on recent deployments of U.S. military personnel. BACKGROUND: Injuries that occur in a deployed military force are more likely to have an immediate and detrimental effect on the military mission than those in garrison or training. These injuries have a direct impact on deployed personnel and unit readiness and consume limited field medical resources. METHODS: Data collected during four recent deployments were evaluated. Administrative databases established for the routine collection of death and hospital admissions were used to characterize mortality and morbidity in the Persian Gulf War. Surveillance teams deployed to Haiti, Somalia, and Egypt provided inpatient and outpatient data for those missions. RESULTS: Data collected by these surveillance systems are presented. Unintentional trauma accounted for 81% of deaths during the Persian Gulf War and 25% of hospital admissions. During operations in Somalia and Haiti, 2.5% to 3.5% of about 20,000 troops in each deployment sought medical treatment for an injury or orthopedic problem each week. In Egypt, injuries accounted for about 25% of all outpatient visits to medical treatment facilities. CONCLUSIONS: Injuries were the leading cause of death and a leading cause of morbidity during recent deployments of U.S. troops. Comprehensive injury surveillance systems are needed during deployments to provide complete and accurate information to commanders responsible for the safety of the force. Recommendations for establishing such systems are made in this article.

Japanese encephalitis vaccine (inactivated, BIKEN) in U.S. soldiers: immunogenicity and safety of vaccine administered in two dosing regimens.

The safety and immunogenicity of Japanese encephalitis (JE) vaccine (Nakayama strain, monovalent / BIKEN) was studied in 538 U.S. soldiers in 1990. Three doses of vaccine from three consecutively manufactured lots were given on days 0, 7, and either 14 or 30. Serum for antibody determination was drawn at months 0, 2, and 6. Japanese encephalitis plaque reduction neutralization tests were performed by three laboratories on each specimen. Five hundred twenty-eight (98%) participants completed the immunization series. All recipients without antibody before immunization developed neutralizing antibody against JE virus. There were no differences in geometric mean titer among the three test lots at months 2 and 6. Soldiers who received the third dose on day 30 had higher titers at both time points. Antibody to yellow fever had no significant effect on immune response to vaccine. Conclusions drawn from analysis of serologic data from the three labs were nearly identical. Symptoms were generally limited to mild local effects and were reduced in frequency with each subsequent does in the series (21% to 11%; P < 0.0001). Generalized symptoms were rare (e.g., fever = 5%) with no reported cases of anaphylaxis.

Survey of U.S. Army soldiers' knowledge, attitudes, and practices regarding personal protection measures to prevent arthropod-related diseases and nuisance bites.

This study examined U.S. Army soldiers' knowledge, attitudes, and practices regarding personal protection measures (PPMs) to prevent arthropod-related diseases and nuisance bites. Soldiers attending 1 of 13 U.S. Army training courses either completed a written questionnaire (N = 1,007) or participated in a group interview (N = 65). Respondents primarily used repellents to prevent nuisance insect bites (55%) rather than to prevent disease (38.7%). Less than one-third correctly identified the military-issue repellents to be used on skin (31.7%) or clothing (26.1%). More than half (57.6%) thought that commercial products were better than military-issue repellents, but most (74.2%) reported that they did not have enough or any information about the U.S. military's system of PPMs. Soldiers have poor knowledge of U.S. military doctrine regarding PPMs and still prefer to use commercial products. A focused strategy to ensure the appropriate use of PPMs by service members should be developed, implemented, and evaluated.

Antibody to a cDNA-derived calreticulin protein from Amblyomma americanum as a biomarker of tick exposure in humans.

The antibody responses of human and animal hosts were studied to determine the utility of antibody against recombinant tick calreticulin (rTC), a cDNA-derived protein isolated from salivary glands of Amblyomma americanum L., as a biologic marker of tick exposure. Rabbits fed upon by either A. americanum or Dermacentor variabilis Say developed significant anti-rTC antibody responses, as measured by both ELISA and immunoblot assay. In contrast, gerbils exposed to Aedes aegypti did not develop anti-rTC antibodies, as measured by ELISA or immunoblot assay. The utility of the assay was next evaluated in humans at high risk for tick exposure. During April through September 1990, 192 military personnel who originated from either Fort Chaffee, Arkansas or Fort Wainwright, Alaska were studied during maneuvers in tick infested areas at Fort Chaffee. Study subjects completed a questionnaire and had pre- and post-maneuvers serum specimens analyzed for antibodies to rTC. In adjusted analysis (controlling for age, fort of origin, attached tick during maneuvers, and bed netting use), the use of bed netting and home station were associated with post-maneuvers anti-rTC antibody seropositivity by ELISA. Subjects from Fort Wainwright were more likely to be seropositive for anti-rTC antibody (adjusted odds ratio = 5.3, 95% confidence interval [CI] = 1.1-25.6). Personnel who did not report the use of bed netting were more likely to be anti-rTC seropositive (adjusted odds ratio = 6.8, 95% CI = 1.4-32.4). Immunoblot assays showed that humans had specific anti-rTC antibody responses. The animal experiments demonstrate that hosts exposed to naturally feeding ticks develop anti-rTC antibodies. The data also indicate that hosts exposed to Ae. aegypti saliva may not develop antibodies against rTC. Observations in tick-exposed humans support the hypothesis that anti-rTC antibody seropositivity is a biologic marker of tick exposure.

Diarrheal disease incidence and morbidity among United States military personnel during short-term missions overseas.

Outpatient medical surveillance of U.S. troops was conducted during 11 different overseas missions between 1981 and 1990. In addition, at the end of each of 18 overseas missions during the same period, a sample of troops was queried regarding illnesses and exposures experienced in the preceding time overseas. Diarrhea was among the leading causes of morbidity during all of these short-term missions. Diarrhea incidence rates were found to be highest during summer months, and were higher during missions to Thailand (median = 25%, range = 20-29%), Latin America (median = 26%, range = 1-43%), and northeastern Africa and southwest Asia (median = 19%, range = < 1-52%). Rates were lowest in troops deployed to the Republic of South Korea (median = 16%, range = 8-27%). During April and May 1990, a focused surveillance and questionnaire study was conducted during a five-week, joint U.S.-Thai military training exercise in central Thailand. Among 2,600 U.S. personnel, diarrheal illness was found to be the most common medical problem for troops (estimated cumulative incidence = 29%). Travel outside of the base of operations and consumption of ice were found to be important risk factors. The 10-year database analyzed for this report is the largest, published summary showing the significant impact of diarrheal diseases on U.S. military forces during short-term deployments to less developed areas.

The risk of birth defects among children of Persian Gulf War veterans.

BACKGROUND: There has been suspicion that service in the Persian Gulf War affected the health of veterans adversely, and there have been claims of an increased rate of birth defects among the children of those veterans. METHODS: We evaluated the routinely collected data on all live births at 135 military hospitals in 1991, 1992, and 1993. The data base included up to eight diagnoses from the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) for each birth hospitalization, plus information on the demographic characteristics and service history of the parents. The records of over 75,000 newborns were evaluated for any birth defect (ICD-9-CM codes 740 to 759, plus neoplasms and hereditary diseases) and for birth defects defined as severe on the basis of the specific diagnoses and the criteria of the Centers for Disease Control and Prevention. RESULTS: During the study period, 33,998 infants were born to Gulf War veterans and 41,463 to non-deployed veterans at military hospitals. The overall risk of any birth defect was 7.45 percent, and the risk of severe birth defects was 1.85 percent. These rates are similar to those reported in civilian populations. In the multivariate analysis, there was no significant association for either men or women between service in the Gulf War and the risk of any birth defect or of severe birth defects in their children. CONCLUSIONS: This analysis finds no evidence of an increase in the risk of birth defects among the children of Gulf War veterans.

Dengue fever in US military personnel in Haiti.

OBJECTIVE: To describe clinical manifestations and public health implications of an outbreak of dengue fever (DF) during Operation Uphold Democracy, Haiti, 1994. DESIGN: Consecutive sample. SETTING: Military combat support hospital, Port-au-Prince, Haiti. PATIENTS: A total of 101 US military personnel with acute febrile illnesses. INTERVENTIONS: A disease surveillance team collected clinical and epidemiologic data from US military clinics throughout Haiti. Febrile patients admitted to the combat support hospital were evaluated with standardized clinical and laboratory procedures. The surveillance team followed patients daily. MAIN OUTCOME MEASURES: Arbovirus isolation and specific antibody determination and symptoms and physical findings. RESULTS: Febrile illnesses accounted for 103 (25%) of the 406 combat support hospital admissions during the first 6 weeks of deployment. All patients with febrile illness recovered. A total of 30 patients had DF; no patient had evidence of infection with malaria. Dengue virus serotypes 1, 2, and 4 were isolated from 22 patients, and 8 patients developed IgM antibody to dengue virus. Patients with DF could not be distinguished from other febrile patients on clinical grounds alone. No arboviruses other than dengue were identified. CONCLUSIONS: Active surveillance, with clinical and laboratory evaluation directed by an epidemiologic team, led to the timely recognition of an outbreak of febrile illness among US troops in Haiti. Viral isolation and serological studies were essential in confirming DF. During the surveillance period, DF accounted for at least 30% of the febrile illnesses among hospitalized US troops. Dengue fever is a significant threat to military personnel and civilian travelers in Haiti and has the potential for introduction to and transmission in the United States.

Plasmodium vivax infections in U.S. Army troops: failure of primaquine to prevent relapse in studies from Somalia.

Different strains of Plasmodium vivax vary in their sensitivity to primaquine, the only drug that prevents relapses. Described are the clinical data and relapse pattern for 75 soldiers treated for vivax malaria since returning from Somalia. Following their initial attack of malaria, 60 of the 75 cases received a standard course of primaquine (15 mg base daily for 14 days). Twenty-six of the 60 soldiers subsequently relapsed for a failure rate of 43%. Eight soldiers had a second relapse following primaquine therapy after both the primary attack and first relapse. Three of these soldiers had received a higher dosage of primaquine (30 mg base daily for 14 days) after their second attack. The apparent ineffectiveness of primaquine therapy in preventing relapses suggests the presence of primaquine-resistant P. vivax strains in Somalia.

Tick avoidance behaviors associated with a decreased risk of anti-tick salivary gland protein antibody seropositivity in military personnel exposed to Amblyomma americanum in Arkansas.

During April through September 1990, 399 military personnel who originated from either Fort Chaffee, Arkansas (n = 236) or Fort Wainwright, Alaska (n = 163) were studied during maneuvers in tick-infested areas at Fort Chaffee. Study subjects completed a questionnaire and had pre- and post-maneuvers serum specimens analyzed for antibodies to several rickettsial and ehrlichial agents and to Amblyomma americanum (lone star tick) salivary gland proteins (anti-tick saliva antibodies [ATSA], a biologic marker of tick exposure). Military rank/grade and home station were associated with pre-maneuvers ATSA seropositivity by enzyme-linked immunosorbent assay (ELISA). Fort Wainwright personnel were more likely to show at least a 50% increase in ATSA levels, compared with subjects from Fort Chaffee, from the pre- to the post-maneuvers specimen (adjusted odds ratio [AOR] = 2.7, 95% confidence interval [CI] = 1.2-6.1). Subjects from Fort Wainwright who did not report use of bed netting were at an increased risk of post-maneuvers ATSA seropositivity (AOR = 4.1, 95% CI = 1.5-11.5). In contrast, subjects from Fort Chaffee who did not report tucking pants into socks were at increased risk of post-maneuvers ATSA seropositivity (AOR = 2.8, 95% CI = 1.1-7.1). Subjects from Fort Chaffee who reported an attached tick bite during maneuvers were more likely to be ATSA-seropositive in the post-maneuvers specimen (AOR = 2.5, 95% CI = 1.2-5.2). Western blot assays revealed large differences in tick salivary gland proteins that were recognized on the post-maneuvers specimen among three randomly selected individuals, and small differences within a single individual who reported a tick bite during maneuvers, comparing pre- and post-maneuvers specimens. The ATSA ELISA seropositivity was not associated with seroconversion to the tick-borne infectious agents.

Comparative mortality among US military personnel in the Persian Gulf region and worldwide during Operations Desert Shield and Desert Storm.

OBJECTIVE: To determine cause-specific mortality rates among US troops stationed in the Persian Gulf region and compare them with those of US troops serving elsewhere during Operations Desert Shield and Desert Storm. DESIGN: Retrospective cohort. POPULATION: US men and women on active duty from August 1, 1990, through July 31, 1991. MAIN OUTCOME MEASURES: Deaths occurring among all active-duty US military persons during the 1-year study period. Age-adjusted mortality rates among US troops stationed in the Persian Gulf region were compared with rates projected from mortality rates among troops on active duty elsewhere. RESULTS: A total of 1769 active-duty persons died during the study period, 372 in the Persian Gulf region and 1397 elsewhere. Of the 372 deaths in the Persian Gulf region, 147 (39.5%) occurred as a direct result of combat during the war, 194 (52.2%) resulted from injuries not incurred in battle, and 30 (8%) resulted from illness. Twenty-three of the deaths due to illness were considered unexpected or cardiovascular deaths. Based on age-adjusted mortality rates observed among US troops on active duty outside the Persian Gulf region, 165 deaths from unintentional injury and 32 deaths from illness (20 of which were unexpected or cardiovascular) would have been anticipated among Persian Gulf troops. CONCLUSION: Except for deaths from unintentional injury, US troops in the Persian Gulf region did not experience significantly higher mortality rates than US troops serving elsewhere. There were no clusters of unexplained deaths. The number and circumstances of nonbattle deaths among Persian Gulf troops were typical for the US military population.

Dengue fever in U.S. troops during Operation Restore Hope, Somalia, 1992-1993.

Dengue fever (DF) was considered to be a potential cause of febrile illness in U.S. troops deployed to Somalia during Operation Restore Hope in 1992-1993. A prospective study of hospitalized troops with fever and a seroepidemiologic survey of 530 troops were conducted. Among 289 febrile troops hospitalized, 129 (45%) did not have an identified cause of their fever. Dengue (DEN) virus was recovered from 41 (43%) of 96 of these patients by inoculation of admission sera into C6/36 cell cultures. Thirty-nine (41%) of the isolates were identified as DEN-2 and two (2%) as DEN-3 by an indirect immunofluorescent antibody assay. An additional 18 (49%) of 37 culture-negative cases were shown by immunoglobulin M (IgM) antibody capture enzyme-linked immunosorbent assay to have anti-DEN virus antibody. All identified DF cases recovered within 1-2 weeks; no case of dengue hemorrhagic fever or shock syndrome was observed. A seroepidemiologic survey of a unit (n = 494) with 17 culture or serologically identified DF cases and a 13% attack rate of unidentified febrile illness revealed a 7.7% prevalence of anti-DEN virus IgM antibody. Failure to use bed nets was the only identified risk factor for DEN infection (adjusted odds ratio = 2.2, 95% confidence interval = 1.4-3.0). These data indicate that DF was an important cause of febrile illness among US troops in Somalia, and demonstrate the difficulties in preventing DEN infection in troops operating in field conditions.

Seroepidemiology of infections due to spotted fever group rickettsiae and Ehrlichia species in military personnel exposed in areas of the United States where such infections are endemic.

A prospective, seroepidemiologic study of spotted fever group rickettsiae (SFGR) and Ehrlichia infections was done among 1194 US military personnel exposed in a heavily tick-infested area of Arkansas in 1990. Seroconversion (4-fold) and seroprevalence rates were determined by indirect immunofluorescent antibody assays. Seroconversions to SFGR occurred in 30 persons (2.5%), whereas seroconversion to Ehrlichia species occurred in 15 (1.3%). The majority of seroconverters did not report symptoms (22/30 [73%] of SFGR seroconverters; 10/15 [67%] of Ehrlichia species seroconverters). History of tick attachment was associated with seroconversion to SFGR (relative risk [RR] = 4.3, P < .001) and Ehrlichia species (RR = 3.6, P < .05). Use of permethrin-impregnated uniforms significantly decreased risk of infection (P < .01); use of bed nets increased risk by 4-fold. Tickborne infections represent a significant threat to military personnel training in areas in which these infections are endemic.

Immunization of US soldiers with a two-dose primary series of inactivated hepatitis A vaccine: early immune response, persistence of antibody, and response to a third dose at 1 year.

To study the feasibility of using inactivated hepatitis A vaccine for rapid immunization of US soldiers, 276 randomized seronegative volunteers received one of four regimens: two injections, on day 0 or one each on day 0 and 14, day 0 and 30, or day 0 and 180. A third dose was given on day 380. Among the 256 recipients of two doses, 99% responded with antibody (by ELISA) with few symptoms. A higher percentage of recipients of both doses on day 0 had antibody at day 14 (68% vs. 52% of all others, P < .03). The highest antibody concentrations (711 mIU/mL on day 240) were observed in subjects given a second dose on day 180. Recipients of the third injection developed a median 15-fold rise in antibody within 2 weeks. Virus-neutralizing antibody was detected in high titers after the third dose and neutralized strains of hepatitis A virus from several countries. Vaccines containing 1440 ELISA units of antigen may be useful for rapid immunization.

Administration of hepatitis A vaccine to a military population by needle and jet injector and with hepatitis B vaccine.

Military personnel are an important target population for hepatitis A immunization. Soldiers are often given vaccines by jet injector and may be required to receive multiple vaccines at one time. Formalin-inactivated hepatitis A vaccine containing 360 ELISA units of antigen was evaluated at Fort Campbell. Volunteers received vaccine at 0, 1, and 6 months as follows: group 1, hepatitis A vaccine by needle; group 2, hepatitis A vaccine by jet injector; group 3, hepatitis B vaccine by needle; and group 4, both hepatitis vaccines by needle in separate arms. Immune response and reactogenicity were evaluated. After two doses, recipients of vaccine administered by jet injector had a higher prevalence of antibody than those who received vaccine by needle (93% vs. 79%). By the 8th month, the vaccine was 100% immunogenic by either route or with hepatitis B vaccine. No interaction between hepatitis A and B vaccines was detected.

Diarrheal disease among military personnel during Operation Restore Hope, Somalia, 1992-1993.

The potential for widespread diarrheal disease was regarded as a substantial threat to U.S. troops participating in the early phases of Operation Restore Hope in Somalia. Outpatient surveillance of 20,859 U.S. troops deployed during the first eight weeks, however, indicated that a mean of only 0.8% (range 0.5-1.2%) of personnel sought care for diarrhea each week, and in three epidemiologic surveys, < 3% of troops reported experiencing a diarrheal illness per week. Despite these low overall attack rates, diarrhea accounted for 16% of 381 hospital admissions and 20% of 245 patients admitted with a temperature > or = 38.5 degrees C. Sixty-one specimens were obtained from inpatients and 52 were obtained from outpatients. Shigella sp. were isolated from 33%, enterotoxigenic Escherichia coli from 16%, Giardia lamblia from 4%, and rotavirus from 1% of 113 stool samples obtained from inpatient (61) and outpatient (52) troops with diarrhea. Bacterial isolates obtained in Somalia were resistant to doxycycline (78%), ampicillin (54%), and sulfamethoxazole (49%), but uniformly sensitive to ciprofloxacin. With the exception of 10 Shigella sonnei isolates that were linked epidemiologically to one eating facility, bacterial pathogens occurred sporadically and demonstrated a wide variation of serotypes and antibiotic sensitivity patterns. Additionally, three of 11 paired sera collected from persons with nausea, vomiting, and watery diarrhea demonstrated a four-fold or greater increase in titer to Norwalk virus antibody. These data indicate that large outbreaks of diarrheal disease did not occur; however, highly drug-resistant enteric bacteria, and to a lesser extent viral and parasitic pathogens, were important causes of morbidity among U.S. troops in Somalia.

Safety and immunogenicity of the oral, whole cell/recombinant B subunit cholera vaccine in North American volunteers.

A newly formulated, oral, inactivated whole cell plus recombinant B subunit (WC/rBS) cholera vaccine was evaluated in US military personnel. In the first study, 74 subjects were given two doses 14 days apart. In the second study, 186 subjects were randomized into four groups; two groups received vaccine with either full (4 g) or half (2 g) strength bicarbonate buffer, and two groups received either full or half strength buffer without vaccine. Mild gastrointestinal symptoms were associated with full buffer (P = .02) but not with the vaccine. In the first study, 36% of all subjects and 55% with low prevaccination titers (< 1:40) had a > or = 2-fold rise in vibriocidal antibody level; > 80% of subjects developed a 4-fold rise in anti-cholera toxin (CT) titers. Post-vaccination IgA and IgG anti-CT titers were approximately 1.5-fold higher among persons receiving full strength buffer (P = .05). The WC/rBS vaccine is safe and immunogenic in North Americans, although some mild gastrointestinal symptoms occur with the high concentration of buffer necessary to protect the B subunit from gastric acid denaturation. Prior immunity to cholera conferred by parenteral vaccine decreased vibriocidal antibody response.

An outbreak of hepatitis A during a military field training exercise.

Hepatitis A continues to pose a preventable threat to modern day military forces. We describe a food-borne outbreak of hepatitis A during a field training exercise resulting in 22 ill soldiers and over 300 lost work days. Among the population at risk, the secondary attack rate was 19.6%. Faced with epidemic disease occurrence, epidemiologic investigation of potential cases and aggressive use of post-exposure prophylaxis is recommended in a field setting. Although immune serum globulin is likely to reduce transmission, not all cases of acute hepatitis A will be prevented by this action.

Attendance and referral patterns in a health promotion program for soldiers.

We studied referral patterns among 505 active duty Army participants in a heath promotion program at Fort Lewis, Washington. Over one-third (35.6%) were referred to health care providers for confirmation of cholesterol or blood pressure screening results. Fifty-two (10.3%) had elevated blood pressure screening measurements, of whom 30% had been previously diagnosed as hypertensive. One hundred forty-six had cholesterol levels greater than or equal to 200 mg/dl, 22.8% of whom were already aware of hypercholesterolemia. Referral for follow-up was not associated with race, sex, or rank after controlling for age. Screening resulted in a large number of referrals for previously unrecognized abnormalities.