By Ania Lichtarowicz BBC science correspondent

More than one in six people who make the annual Islamic pilgrimage to Mecca and Medina return carrying meningococcal bacteria, according to a study published in the British Medical Journal.

The doctors behind the work advise that all Hajj pilgrims and their families be vaccinated against the many types of meningitis before leaving home.

Pilgrims and their families should be vaccinated

This research reinforces previous calls for Muslims travelling to the annual Hajj to receive an improved meningococcal vaccination before they travel.

Hundreds of thousands of Muslims from around the globe travel to Saudi Arabia to take part in the pilgrimage.

Because of the sheer number of people, as well as their close proximity to each other in crowded sites, diseases - particularly the bacteria which cause meningitis - can spread quickly between the pilgrims.

This latest research was carried out in Singapore. More than 200 pilgrims were tested before and after the pilgrimage:

• 17% carried meningococcal bacteria

• Of these, 90% had one particular type of meningitis bacteria - W135

• This strain caused an international outbreak of meningococcal disease during the Hajj in 2000

Broad vaccine

At least 1.2 million cases of bacterial meningitis are estimated to occur every year - 135,000 are fatal.

Antibiotics can reduce the transmission of the bacteria - giving these to the pilgrims will also help curb the spread of disease to their families once they return home. However some doctors believe that vaccines are more effective.

Many countries already vaccinate against the A and C strains of the disease, but doctors behind this study say a broader vaccine should now be compulsory for pilgrims and their relatives.

This vaccine would also work against the W135 strain not only protecting the pilgrims but also their families.