Table 1A.

Disease	Minimum infectious dose	Foods associated with outbreaks	Factors contributing to foodborne illness	Control measures	Criteria for confirming an outbreak
Hepatitis A	Probably low, 10–100 virus particles	Fecal-contaminated water and shellfish, other foods via ill food handlers or contaminated water used for cleaning or irrigation	Eating raw or insufficiently cooked shellfish, infected persons preparing or serving food, drinking fecal-contaminated water	Monitor shellfish harvest areas for fecal contamination, consumption of raw shellfish should be discouraged, cook shellfish well, monitor drinking water for fecal contamination, good personal hygiene of food handlers	Demonstration of liver dysfunction (high enzyme levels), presence of IgM-specific antibody, a 4-fold rise in specific antibody in paired serum samples
Non-A, non-B hepatitis	As above	Fecal-contaminated water	Drinking fecal contaminated water	Monitor drinking water for fecal contamination	Suspected if screening rules out other known hepatitis agents
Norwalk or Norwalk-like gastroenteritis	Presumed to be low, 1 virus particle may infect	Fecal-contaminated water and shelfish, other foods via ill food handlers	Eating raw or insufficiently cooked shellfish, infected persons preparing or serving food, drinking fecal-contaminated water	Monitor shellfish harvest areas for fecal contamination, consumption of raw shellfish should be discouraged, cook shellfish well, monitor drinking water for fecal contamination, good personal hygiene of food handlers	Identification of virus in feces by immunoassay methods or immune electron microscopy, a 4-fold rise in specific antibody in paired serum samples