W135 meningococcal carriage in association with the Hajj pilgrimage 2001: the Singapore experience.

An international outbreak among pilgrims returning from the Hajj (pilgrimage to Mecca) and their close contacts was caused by W135 Neisseria meningitidis. In Singapore, this strain is a new emerging problem, clearly associated with this outbreak. We investigated the extent of transmission of N. meningitidis in Hajj pilgrims and their contacts, in order to provide evidence for developing a rational public health policy. We found a high acquisition rate of W135 N. meningitidis in Singaporean pilgrims during the Hajj with substantial transmission to their household contacts. These findings would support a policy of eradication of pharyngeal carriage in returning pilgrims to prevent introduction and dissemination of meningococci.