A hospital-based, case-control study of risk factors for hemorrhagic fever with renal syndrome in soldiers of the armed forces of the Republic of Korea.

A hospital-based, case-control study was conducted to measure risk factors for hemorrhagic fever with renal syndrome in Korean soldiers. Between October 1989 and January 1992, 196 cases and 295 controls were admitted into the study. Information was collected on behavioral and environmental variables, and the data were analyzed by multiple logistic regression. The strongest risk factors were seeing Apodemus in the area (odds ratio [OR] = 4.9), living in a primitive dwelling such as a lean-to (OR = 3.9), and being exposed to dust (OR = 3.7). The most protective factors were living in barracks (OR = 0.3-0.5) and self-reported use of any insecticide or insect repellent (OR = 0.5).

Prevention of adenoviral acute respiratory disease in Army recruits: cost-effectiveness of a military vaccination policy.

INTRODUCTION: Since 1971 widespread vaccination has limited the number of adenoviral acute respiratory disease (ARD) outbreaks in Army recruits. Increased vaccine costs have recently threatened the continuation of the vaccination program. METHODS: We conducted a cost-effectiveness analysis to assess the consequences of changing the year-round Army adenovirus vaccination program to (1) seasonally targeted vaccine administration (only during the high-risk period) or (2) complete discontinuation of the program from the perspective of total cost to the Army. Costs included vaccination costs and direct and indirect medical and military training costs. Health outcomes were estimated as the number of hospitalizations for ARD prevented. In the reference case, the incidence rate among unvaccinated and vaccinated individuals was 4.06 and 1.5 per 100 person weeks, respectively. Results are expressed for a cohort of 76,171 recruits. RESULTS: In the absence of adenoviral vaccination, a projected 12,370 cases of ARD hospitalization would occur, costing $26.4 million annually. A seasonally targeted program would prevent 7,800 cases of ARD and save $16.1 million over no vaccination. Year-round immunization would not prevent any additional cases but would save $15.5 million over no vaccination. Year-round vaccination would become the cost-effective strategy if ARD incidence during the low-risk months were to increase. CONCLUSION: Vaccination of Army recruits by any schedule was cost-saving due to the high level of prevented disease and averted hospitalizations. Even though a seasonally targeted program provided the greatest cost-savings, year-round vaccination must remain an option due to the potential for adenoviral ARD outbreaks in the low-risk period.

The epidemiology of varicella hospitalizations in the U.S. Army.

Varicella infections affect the U.S. Army, but the extent has not been quantified recently. We obtained 1990 to 1997 hospitalization data from the U.S. Army Medical Command and calculated rates using data from the Army Medical Surveillance Activity and the U.S. Army Training Command. There was a decline in the number and incidence of varicella hospitalizations for U.S. Army active duty soldiers from 1990 to 1997. Varicella incidence rates for active duty soldiers are significantly higher for females, blacks, those younger than 20 years, and those whose home of record were tropical island regions. Army initial entry training hospitalizations constitute 11.8% of active duty Army hospitalizations and have also declined. Varicella continues to affect the training and health of the U.S. Army; however, the impact has diminished over the years. A feasible approach to limit varicella in the U.S. Army is to target trainees for screening or vaccination. Refinement of this strategy should be determined from a follow-up cost-effectiveness analysis.

The cost-effectiveness of varicella screening and vaccination in U.S. Army recruits.

Varicella outbreaks in the U.S. Army disrupt training, reduce readiness, and represent substantial costs. Vaccination of susceptible individuals may be cost-effective. We conducted a cost-effectiveness analysis comparing screening of all incoming recruits and vaccination of susceptible individuals at either initial entry training (IET) or medical entrance processing station (MEPS), universal vaccination at IET, and no intervention. Primary health outcomes included the number of varicella cases prevented during the 8-week initial training period. The varicella hospitalization rate was 21.6 per 10,000 per year. In 100,000 recruits, 36 cases of varicella are expected at a cost of $181,000 in the absence of an intervention. Screening at IET would prevent 4 cases but would cost an additional $3,255,000 more than no intervention. Screening at MEPS would prevent 3 cases and save $521,000 per case prevented during the IET but would cost $2,734,000 more than no intervention. Universal vaccination would prevent 2 cases but would cost $15,858,000 more than MEPS screening and $18,592,000 more than no intervention. These results are robust. Cost per case of varicella prevented ranged from $390,000 to $7.9 million. Scarce prevention resources could be more cost-effectively allocated to other prevention programs.

An analysis of duty restrictions of aviation personnel in the Republic of Korea.

Aviation medical records were reviewed from four U.S. Army medical clinics in the Republic of Korea for flying duty restrictions over a 1-year time period. Duty restrictions were catalogued into 1 of 15 different diagnostic categories and compared by parameters of duration, time of year, crew status, age, and sex. Four hundred twenty-eight records were reviewed. Respiratory illnesses were the most common cause of flight restriction, followed by gastrointestinal and musculoskeletal problems. Flight personnel averaged 12.8 days a year on restrictions. Non-crewmembers were frequently not restricted for treatments that should have required restriction, but when restricted, averaged a significantly longer period of time than crewmembers. Females averaged significantly fewer days out for restrictions, and there were large differences in the number of days out by age for certain restrictions, but the numbers were small. There were some seasonal variation noted in patient visits with fewer visits in the spring and summer.

Strain variation in adenovirus serotypes 4 and 7a causing acute respiratory disease.

In order to determine the suitability of vaccine strains established in the 1960s for a new vaccine, a comprehensive study of strain variation of adenovirus serotype 4 (AV 4) and AV 7 was undertaken. A 1,500-bp region of the hexon gene containing the AV neutralization epitopes from prototype, vaccine, and community-acquired strains and from wild-type strains from military personnel that cause acute respiratory disease (ARD) was sequenced and analyzed. The whole hexon gene from prototype strains, vaccine strains, and selected isolates was sequenced. AV 7 and AV 7a were found to have distinct genotypes, and all vaccine and wild-type strains recovered from 1963 to 1997 had the AV 7a genotype. There was no significant strain variation in the neutralization epitopes of the AV 7a genotype over a 42-year period. The evolution of AV 4 was more complex, with continuous genetic drift punctuated by replacement with a new strain. The current strain of AV 4, which has been in circulation since 1995, is significantly different from the AV 4 prototype and the vaccine strains. Genetic differences were confirmed to be antigenic differences by neutralization tests, which define the new strain as an AV 4 variant. A type-specific PCR for AV 4, AV 7/7a, and AV 21 was developed, and this PCR facilitated the rapid identification of isolates from outbreaks of ARD.