An Outbreak of Hepatitis-a Associated With Recreational Lake Water1

In a 15-day period in September 1969, 14 cases of viral hepatitis, type A (hepatitis-A), developed in members of a Boy Scout Troop who had been camping on an island in a lake recreation area approximately four weeks earlier. The clustering of cases by onset date over a short time interval, the appearance of cases only among those troop members attending the campout, the absence of known prior exposure to hepatitis-A and the absence of hepatitis-B antigen in all but one of the cases, suggested a common-source exposure to hepatitis-A virus. Raw lake water, which was grossly contaminated and inadvertently consumed by many campers, was associated with a statistically significant risk of hepatitis-A. Since use of recreational waters continues to be a very popular pastime, physicians should be alert to the possibilities that acquisition of hepatitis-A can occasionally result from such activities.