Objective To asses the correlation factors of a hepatitis A outbreak.Methods A 1∶2 case-control study was carried out,56 cases of acute hepatitis A and 112 controls were interviewed. A questionnaire was administered to all subjects by one of the authors.Odds ratios and their 95% confidence limits were computed.Results Jiaban shrimp was the dietary factor of hepatitis A outbreak. The relative risk of eating raw Jiaban shrimps were 19.82 times than that of no eating, and there existence relationship of dos...