Vaccine against 'Delhi belly'

Travellers may soon be offered vaccination against the onslaughts of "Delhi belly" or "Montezuma's revenge", which spoil so many holidays to remote parts of the world.

But recent research has also confirmed that simple personal hygiene already greatly reduces the chances of catching diarrhoea.

The pharmaceutical industry reckons there is a $1 billion a year market for effective protection and firms are racing to bring products to market. Heading the pack is Chiron Corporation, which has developed Dukoral, an oral vaccine taken as a drink in two doses at least a week before departure, which is said to provide up to three months' protection against infection.

Dukoral is already licensed in Canada, New Zealand, Scandinavia and a dozen other countries. The vaccine, to be manufactured by Powderject Pharmaceuticals, based in Oxford, England, is expected to be on sale within a year. That makes it the first vaccine for travellers' diarrhoea to be brought to market.

Similar vaccines are in development by other companies, including Microscience, a British biotechnology company, which this month reported successful completion of Phase 1 safety trials in 36 volunteers. But Microscience said it could be "four or five years" before patients can go to their doctor and ask for its product in order to avoid tummy trouble abroad.

A recent study published in the British medical journal, the Lancet, found, unsurprisingly, that the risk of getting diarrhoea is lower in western Europe and North America, with an estimated 7 per cent of travellers affected, than in developing countries, where the risk rises to 20 to 50 per cent. Just over half of all visitors to Kenya and India fell victim to diarrhoea.

But the study also found that British travellers were the most likely to suffer, with the difference put down to personal hygiene, namely the failure of British tourists to wash their hands. The travellers being studied "ate at the same hotels, ate the same food and were there at the same time," said one of the authors. "So it has to come down to personal habits."

In other words the traditional advice doctors give to travellers, to "boil it, cook it, peel it or forget it," still holds good.

But even careful personal hygiene does not always work, and often is not practicable, which is where products like Dukoral come in. In a study in Bangladesh of almost 90,000 adults and children, it reportedly prevented two-thirds of cases of diarrhoea caused by E Coli, compared with a control group, and 85 per cent of cases of cholera.

But the manufacturers warn that, even when Dukoral does come on the market, travellers who take it cannot assume they have immunity against all the bugs that cause stomach trouble. Other causes of diarrhoea including salmonella, shigella, camphylobacter and crytosporidium will still be out there waiting for the unwary.

- INDEPENDENT