PRIMADELI cakes, currently behind an islandwide wave of food poisonings, could have been contaminated by eggs or cream laced with bacteria, an infectious disease expert said yesterday.

Or, bacteria-carrying food handlers may not have washed their hands properly after hitting the loo, said Associate Professor Dale Fisher, a senior consultant from the National University Hospital's division of infectious diseases.

'This is why our mothers taught us to wash our hands after going to the toilet and before meals,' he said.

 In the last two weeks, at least 109 people here have been stricken with severe diarrhoea, stomach pains and fever after eating chocolate cakes from the PrimaDeli bakery chain.

Eight people were hospitalised, but have since been discharged.

Two of the bakery's workers have tested positive for the salmonella enteritidis bacteria - which had also been found in the hospitalised patients - even though they had not been sick. That suggests they may be carriers.

Carriers do not develop symptoms because their immune systems are strong enough to keep the bacteria at bay. However, they can excrete the bacteria in their stool for as long as a year.

No treatment is available, or required, for carriers. The immune system will flush the bacteria out naturally over time.

If they wash their hands, wear gloves, and cook food properly, they should not spread the bacteria, Prof Fisher said.

Baking the PrimaDeli cakes at high heat would have killed the bacteria, but hazelnut cream - believed to contain the bacteria in this case - is not subjected to this process.

People who catch the salmonella bacteria usually experience the mild form of the disease.

Medication is given to relieve symptoms like fever and pain until inflammation of the intestines, brought on by the bacteria, subsides.

Those with a serious case of salmonella poisoning may need to be hospitalised, and given antibiotics and fluids to ensure they do not become dehydrated or go into shock.

The elderly, children and those whose immune systems are weakened by other conditions, such as kidney failure or diabetes, are at higher risk of developing severe illness.

In less than 5 per cent of patients, the bacteria enter the bloodstream and can cause organ failure or death.

The risk of this potentially lethal complication is what makes salmonella infections more dangerous than those caused by other more common bugs, Prof Fisher said.

It is also why the Health Ministry requires doctors here to register salmonella-infected patients.

Last year, 377 people here came down with various salmonella infections, compared with more than 112,200 treated for diarrhoea at polyclinics.

So far this year, 255 people were reported to have suffered salmonella infections.

Meanwhile, the authorities have ordered PrimaDeli to recall all its products, and shut down its factory until the company can prove it is clean. Investigations into the outbreak are ongoing.