Meningococcal carriage among local inhabitants during the pilgrimage 2000-2001.

The first international outbreak of Neisseria meningitidis serogroup W135 occurred in 2000, in direct association with the annual Hajj in Saudi Arabia. In anticipation of the following Hajj, we conducted a survey of oropharyngeal carriage rates of N. meningitidis both pre- and post-pilgrimage in the King Khalid National Guard Hospital (KKNGH) employees preparing to attend the Hajj. These KKNGH employees were native to the Mecca-Jeddah area. Pre-Hajj throat cultures were obtained 1 week prior to Hajj, and post-Hajj cultures within 10 days after completing the Hajj pilgrimage. A total of 327 throat culture samples were collected from 218 persons. Overall meningococcal carriage rate was found to be 4.7%. Serogroup W135 accounted for 40% of all recovered pre-Hajj strains of N. meningitidis. Only one post-Hajj sample was positive for N. meningitidis W135. This high rate of colonization with N. meningitidis serogroup W135 indicates this strain predominates amongst the population indigenous to the Mecca-Jeddah area. This 'nidus' of N. meningitidis W135 is a potential reservoir for future outbreaks. More worrying, there is real risk of future W135 endemicity in this vulnerable local population. These preliminary findings warrant larger surveillance studies examining both transmission and carrier rate acquisition of N. meningitidis in the Mecca-Jeddah area. These vital data are needed to curb further epidemic outbreaks during future Hajj pilgrimages.