Bacillus Cereus is a common soil organism, found on many sorts of vegetable matter destined for human consumption (notably rice), and is a spore-former and consequently resistant to drying and heating.
Episodes of food-poisoning associated with its presence in food have been reported from as far back as 1906, and have been more frequently recognized since 1950, but since 1971 a special association with Chinese fried rice has been noted in many countries.
The typical story behind an outbreak of this kind is that the rice has been boiled (which does not destroy Bacillus Cereus) and then allowed to remain warm for many hours before being lightly fried. The organism multiplies briskly in the warm rice if it is in the range 30-37 C, and produces one or more enterotoxins, which are not destroyed by the final frying.
Two distinct pictures can be recognized, and are due to differences between strains of Bacillus Cereus in the number and proportions of toxins that they produce. Most of the rice-associated outbreaks are characterized by nausea and vomiting coming on I to 5 hours after eating the rice.
In contrast, vomiting was uncommon in most of the outbreaks of the kind recognized in earlier years, which were characterized by abdominal pain and diarrhea coming on 8 to 16 hours after eating the food responsible.