B. cereus Food Poisoning Assoc. This report summarizes the investigation of this outbreak. A case was defined as vomiting by a person who was present at either day care center on July 21. Twelve of the 14 cases occurred among children aged 2.5-5 years, and two occurred among staff. The rice had been cooked the night of July 20 and cooled at room temperature before refrigeration.
Fever is uncommon with either syndrome.
The diagnosis of B. cereus food poisoning can be confirmed by the isolation of greater than or equal to 105 B. cereus organisms per gram from epidemiologically implicated food. Underreporting of such outbreaks is likely because illness associated with B. cereus is usually self-limiting and not severe. B. cereus is frequently present in uncooked rice, and heat-resistant spores may survive cooking. In the outbreak described in this report, vegetative forms of the organism probably multiplied at the restaurant and the day care centers while the rice was held at room temperature. The day care staff and restaurant food handlers in this report were unaware that cooked rice was a potentially hazardous food.