March 1998

Bacillus Cereus food poisoning is a gastrointestinal intoxication caused by toxins produced by the Bacillus Cereus bacteria.
There are two types of toxin, - the Diarrhoeal (causing diarrhoea) and the Emetic (causing vomiting).

The Symptoms
Symptoms with the diarrhoeal toxin are nausea, cramplike abdominal pains and watery diarrhoea, beginning 8 to 16 hours after eating and are related to the lower intestine. With the emetic toxin the symptoms are more severe and acute and are nausea and vomiting beginning 1 to 6 hours after eating and are related mainly to the upper intestine.
The diagnosis is confirmed by a laboratory test on a faecal specimen.
The illness occurs when people swallow the bacteria or spores formed by them which then multiply and produce toxin in the intestine, or from eating the toxin already produced in food.

It's Source
Common sources of infection include:

• raw, dried or processed foods such as cereals, cornflower, spices, and other dried foods.
• the general environment including soil, air, dust, water and decaying matter.
• animals.
• foods such as turkey, beef, seafood, salads, potatoes, rice, noodles, food mixes -(sauces, soups, casseroles), milk powder, various bakery products and desserts especially items with custard and cream.

Duration
The illness in either form usually only lasts between 12 to 24 hours.

Treatment
Generally no specific treatment is needed except for fluid replacement if necessary.

Re-infection
As yet it is unclear if any resistance is gained against reinfection.

Spread to Others
This illness is not spread from person to person.

Work and School
Everyone with this infection should stay off work or school while they have symptoms especially those in High Risk groups, occupations or institutions (infants or children in daycare, school pupils, students, food workers, child-care workers, teachers, and health/care workers).

Reducing the Risk
Bacillus cereus exists in normal bacterial and spore forms in foods. The normal form is inactivated by cooking, but most illness is a result of the multiplication of spores during inadequate refrigeration of moist cooked protein foods and rice. Because cooking often kills competing bacteria and heat activates the Bacillus cereus spores, storing large masses of cooked food between 4 deg C and 60 deg C can allow the bacteria to multiply.

Preventive measures that can be taken to help avoid the illness include:

• Ensuring adequate temperatures are reached during cooking of food mixes such as sauces, custards, and soups to inactivate the bacteria.
• Keeping cooked hot foods above 60 deg C (preferably 70 deg C) if not served immediately.
• Ensuring the rapid cooling of cooked food by dividing into smaller lots and refrigerating in shallow containers (less than 10cm deep).
• Storing cold foods at or below 4 deg C to prevent toxin being produced.
• Avoiding storing protein-containing foods with cooked rice because this stimulates the growth of Bacillus cereus.
• Reheating foods to 75 deg C or until steaming hot, as flash frying or brief rewarming is not adequate to destroy the toxin.
• Preventing cross-contamination from raw to cooked foods (by using separate preparation areas or sanitising between processes).
• Thoroughly washing fruit and vegetables with clean water of drinking standard before use.
• Ensuring food handlers have good personal hygiene and adequate food safety training.

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