Meningococcal disease and prevention at the Hajj.

The Islamic Hajj pilgrimage to Mecca, Kingdom of Saudi Arabia (KSA) has historically been associated with outbreaks of Neisseria meningitidis serogroup A. The main means of prevention against meningococcal disease was the bivalent serogroup A/C polysaccharide vaccine. During the Hajj pilgrimages of 2000 and 2001, there was an epidemiological shift from serogroup A disease to serogroup W135 disease together with an increase in incidence in younger age groups. This prompted the Ministry of Health to introduce quadrivalent ACYW135 polysaccharide vaccines. These interventions have quelled meningococcal disease since 2002. Trials on meningococcal quadrivalent conjugate vaccines are now underway in the KSA.