IN MARCH 1997, a total of 153 cases of hepatitis A were reported in Calhoun County, Michigan (1990 population: 136 000); 151 case-patients have been students or staff of schools in four different school districts. Investigation by public health officials has not implicated a single event, foodhandler, or contaminated water as a source for the outbreak. However, most case-patients ate lunch in schools, and preliminary analysis of both a case-control and cohort study conducted in two different school districts established a strong association between illness and consumption of food items containing frozen strawberries. This report presents the preliminary findings of the ongoing outbreak investigation.
The strawberries associated with illness were reportedly from Mexico; a company in southern California processed, packed, and froze the strawberries in 30-pound containers for commercial use and then distributed the strawberries to U.S. Department of Agriculture (USDA)-sponsored school lunch programs. In addition, multiple packing
Hepatitis A Associated With Consumption of Frozen Strawberries—Michigan, March 1997. JAMA. 1997;277(16):1271. doi:10.1001/jama.1997.03540400021008