Hope raised for diarrhoea vaccine

E. coli causes diarrhoea

A vaccine to prevent travellers from tummy trouble has produced promising results in trials.

The vaccine, taken as a drink, is designed to protect against the most common cause of diarrhoea - the bacterium enterotoxigenic E coli.

However, the researchers, from St George's Hospital, London, warn it could be five years before it is made widely available.

Tests showed the vaccine was safe, and able to stimulate an immune response.

A single dose was enough to trigger significant activity in the immune systems of half of the 36 volunteers who were given the vaccine, called spi-VEC. After two doses, the figure rose to 70%.

Dr Steve Chatfield, chief scientific officer at Microscience, a biotechnology which has worked on the vaccine, said servicemen and women travelling abroad would be recruited to take part in future tests.

New generation of drugs

He said: "The results exceeded our expectations and pave the way for the development of a whole new generation of oral vaccines which are safe, easy to administer and effective.

"A lot of the armed forces serve in areas where this (ETEC) is endemic so this could be useful to help them carry on with their duties."

He said it was also possible that the vaccine had the potential to help protect people living in areas of high infection.

However, this would depend on how long the vaccine remained effective once it had triggered an immune response, and how often top ups would be needed.

At the moment the aim is that each jab will provide six months' protection.

The vaccine is made from salmonella bacteria which have been made harmless by the removal of key genes. Chemicals from ETEC are added to this to stimulate an immune response.

Even though the vaccine itself is harmless, the immune system recognises it as a threat, and mounts action to try to destroy it.

Professor Ron Behrens, of the London School of Hygiene and Tropical Medicine, said research would be more valuable if it concentrated on how to prevent diarrhoea occuring among people who live in the developing world.

It is estimated that diarrhoea kills 500,000 a year world-wide.

In contrast, said Professor Behrens, most cases of travellers' diarrhoea were in no way serious, and only lasted for one to two days.

He said: "Diarrhoea is caused by well over 100 known pathogens, so this vaccine will only be effective in a limited number of cases."

A second vaccine for diarrhoea, known as Dukoral, is due to come on to the market within the next year.