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Hepatitis A associated with consumption of frozen strawberries--Michigan, March 1997
Abstract:
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.
Insights
A Hepatitis A outbreak in Michigan was linked to frozen strawberries served in schools. Public health officials identified a strong association between illness and consuming these strawberries.
Area of Science:
- Epidemiology
- Public Health
- Infectious Disease Control
Background:
- A significant Hepatitis A outbreak occurred in Calhoun County, Michigan, in March 1997.
- The outbreak primarily affected students and staff across four school districts, with 153 reported cases.
Purpose of the Study:
- To investigate the source and transmission of the Hepatitis A outbreak in Calhoun County schools.
- To identify specific food items associated with the outbreak through epidemiological studies.
Main Methods:
- Conducted a case-control and a cohort study in two affected school districts.
- Analyzed consumption patterns of school lunch items among case-patients and controls.
- Investigated potential sources including single events, foodhandlers, and water contamination.
Main Results:
- No single event, foodhandler, or contaminated water source was definitively implicated.
- Preliminary analysis revealed a strong association between Hepatitis A illness and consumption of food containing frozen strawberries.
- Most case-patients reported eating lunch at their respective schools.
Conclusions:
- Frozen strawberries served in school lunches are strongly suspected as the source of the Hepatitis A outbreak.
- Further investigation is ongoing to confirm the link and implement control measures.
- This highlights the importance of food safety in institutional settings to prevent widespread infectious disease transmission.