Bacillus cereus can cause two distinctive forms of food poisoning. Both are caused by enterotoxins.
Emetic food poisoning is caused by the ingestion of emetic toxin that has been pre-formed in food. It causes general malaise, nausea and vomiting and occasionally diarrhoea. This type of food poisoning has been linked with starchy foods such as cooked rice, pasta and noodles.
Diarrhoeal food poisoning is caused from the formation and release of enterotoxin in the small intestine. However, the enterotoxin can also be pre-formed in food. It causes diarrhoea and abdominal cramps - occasionally nausea, vomiting, fever, chills and body aches.
Bacillus cereus is ubiquitous in nature, commonly found in soil (especially rice paddy soil) and vegetation. It has been isolated from many foods, including cereal and cereal derivatives, spices, milk and dairy products, vanilla sauce, recipe dishes, chicken soup, mashed potatoes, vegetables, rice dishes and dried foods.
Mesophilic strains of Bacillus cereus grow within the range of 10ºC - 50ºC with an optimum of 28ºC - 35ºC. However, psychrotrophic strains are capable of growing and producing toxin at temperatures as low as 4ºC.
Bacillus cereus is a spore former, so although its vegetative cells are destroyed by pasteurisation, it requires quite a severe heat process to destroy the spores.