This number exceeds the total number of cases in association with last year's Hajj

Dr Pat Troop, deputy chief medical officer

The W135 strain of meningococcal bacteria responsible for the outbreak is not found in this country, but is prevalent in Saudi Arabia.

It is the same strain responsible for a separate outbreak following last year's Hajj pilgrimage.

On that occasion, there were 13 cases and four deaths.

Vaccines ineffective

Normal immunisation against meningitis is ineffective, but a quadrivalent vaccine which covers the strain has been made available to prospective Hajj pilgrims.

However, the Public Health Laboratory Service estimates that uptake prior to this year's pilgrimage was poor, with only one in two people receiving the vaccine.

Performing the pilgrimage at least once in a lifetime is considered one of the five central duties of Islamic life.

Approximately 2m are thought to have converged on the city of Mecca in February and March 2001.

Dr Pat Troop, deputy chief medical officer, who circulated the warning to doctors, said: "This number exceeds the total number of cases in association with last year's Hajj.

"General practitioners and accident and emergency departments should be alert to the diagnosis of meningococcal infection in pilgrims themselves, but also in those who may have been in contact with pilgrims returning from this year's Hajj."

She recommended that any suspicion of meningitis should lead to rapid treatment with powerful antibiotics.

Meningococcal disease, in which bacteria invade the bloodstream, can kill within hours unless diagnosed and treated.

In many cases, the bacteria live harmlessly in the back of the throat, and doctors are unsure what factors might trigger the infection and disease.

The first noticeable symptoms are the trademark purple or red rash, which does not fade when pressed with the side of a glass, a high fever, a stiff neck and aversion to light.

Patients may also suffer a severe headache and vomiting.