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.