Hepatitis A associated with consumption of frozen strawberries--Michigan, March 1997.

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.