Scientists believe they can eradicate the bug

The veterinary microbiologists have identified the source of the bug in cattle.

E.coli is common in cattle and sheep and is spread to humans either by direct or indirect contact with animal faeces.

Veterinary microbiologists at Edinburgh University discovered that the majority of the bacteria can be found just inside the animal's rectum.

This knowledge gives us the potential to identify, control and ultimately eradicate E.coli O157 Dr David Gally

The breakthrough came after the discovery of a different cell type lining the gastrointestinal tract.

Dr David Gally said: "This knowledge gives us the potential to identify, control and ultimately eradicate E.coli O157 in the minority of livestock that are carriers of the bacterium.

"Faecal contamination was known as the principal cause of infection in humans and abattoirs have already introduced practices to minimise the risk of contaminating carcasses.

Vaccine hopes

"This new discovery will permit additional risk management procedures and should lead quite quickly to both direct interventions and more sophisticated controls, such as vaccines."

Scientists are now conducting research to uncover the molecular nature of the cell type and why it interacts in cattle with E.coli O157.

They believe the interaction between cattle and the bacterium will have important implications for vaccine development.

Scientists are now working with a major pharmaceutical company to develop materials to eliminate the E.coli O157 bacterium from the food chain.

Potentially fatal

The collaborative research programme also involves the Scottish Agriculture College, the Moredun Research Institute and the US-based Washington State (Pullman) University.

The work is funded by the Department of the Environment, Food and Rural Affairs (Defra).

Humans who contract E.coli suffer severe stomach cramps and bloody diarrhoea which can lead to severe kidney damage in young children.

It is potentially fatal among the very young and elderly.