British Muslims taking part in the Haj, the annual Islamic pilgrimage, should have compulsory antibiotic treatment on their return to stop the spread of potentially fatal meningitis, doctors say.

Nearly one fifth of pilgrims returning from the Haj have been found to be carrying exotic strains of the meningitis bacterium, according to research published today in the British Medical Journal.

The disease is relatively rare in Britain, although in 2001 an outbreak of the W135 strain of meningococcus caused 10 deaths. But this strain is common in Saudi Arabia, where the Haj climaxes in March with nearly 2 million Muslims from around the world converging on the holy city of Mecca.

The 20,000 Britons who went on the Haj this year were strongly encouraged by the Department of Health and the Association of British Hujaj (pilgrims) to have meningitis vaccinations first, and the Saudi Arabian government now requires people to have a valid meningitis certificate before it will issue a visa.

However, the new findings suggest that that is only half of the necessary action, because the vaccine does not prevent people from becoming carriers of the disease bacteria.

In the BMJ study, researchers in Singapore took throat swabs from 204 pilgrims leaving for the 2001 Haj before they left, and repeated it on 84 per cent on their return. They found that 17 per cent of those who returned were carrying meningitis bacteria, with 90 per cent carrying W135.

Many countries give "bivalent" meningitis vaccinations that protect against two strains of the bug, but Haj travellers should be given the "quadrivalent" version which also protects against W135, they recommend.

Even with those precautions, people could become carriers; antibiotics are recommended, and should be considered for anyone they live with, the doctors say.