Aetiological agent is Bacillus cereus bacteria toxin. B. cereus can cause two different types of foodborne illnesses: the diarrhoeal type and the emetic type. Diarrhoeal toxin causing toxico-infection due to production of heat-labile toxins either in the gut or in food.
The enterotoxins are produced during vegetative growth of B. cereus in the small intestines. Emetic toxin causing intoxication due to heat stable toxin produced in food. For both types of foodborne types of food borne illness is caused by a toxin that is performed by B. cereus while growing in the food.
Epidemiology
The bacteria are Gram-positive, facultative anaerobic, motile rod that produces heat-resistant spores; generally mesophilic, grows at 10-50°C (optimum temperature 28-37°C), pH 4.3-9.3 and water activity (aw)>0.92.
Spores are moderately heat-resistant and survive freezing and drying. Some strains require heat activation for spores to germinate and outgrow. It is found abundantly in environment and vegetables.
Symptoms
Symptoms for diarrhoeal syndrome are acute diarrhoea, nausea and abdominal pain. Symptoms for emetic syndrome acute nausea, vomiting and abdominal pain and sometimes diarrhoea.
The incubation period is 8-16 hours for diarrhoeal syndrome while the incubation period for emetic syndrome is 1-5 hours. The diarrhoeal syndrome lasts 24-36 hours while emetic syndrome lasts 24-36 hours (Hirsh, Maclachian, & Walker, 2004).
Mode of transmission
Ingestion of food that has been stored at ambient temperatures after cooking, permitting the growth of bacterial spores and toxin production. Many outbreaks (particularly those of the emetic syndrome) are associated with cooked or fried rice that has been kept at ambient temperature.
Foods involved include starchy products such as boiled or fried rice, spices, dried foods, milk, dairy products, vegetable dishes and sauces.
Control and prevention
Food service establishment or household require effective temperature control to prevent spore germination and growth. Food storage at >70°C or <10°C until use unless other factors such as pH or water activity prevent growth.
When refrigeration facilities are not available, cook only quantities required for immediate consumption. Toxins associated with emetic syndrome are heat resistant and reheating, including stir-frying, will not destroy them. Good hygiene practices during production and processing.
Incidences are occurring worldwide.
References
- Hirsh, D., Maclachian, J., & Walker, R. (2004). Botulism in Veterinary Microbiology (2nd ed.). Washington, DC: Blackwell Publishing.
