Neisseria meningitidis Serogroup W135 Isolates Associated with the ET-37 Complex

摘要

To the Editor: As of April 20, 2000, >300 laboratory- confirmed cases of meningococcal disease caused by N. meningitidis serogroup W135 (NMW135) have been reported in Saudi Arabia and nine other countries among Hajj pilgrims or their close contacts (1). This is the first reported multinational outbreak of W135 meningococcal disease. NMW135 accounts for <5% of meningococcal disease in the United States and worldwide. The main cause of meningococcal disease outbreaks, especially in the African “meningitis belt,” which extends from Ethiopia in the east to Senegal in the west, has long been N. meningitidis serogroup A. An epidemic, caused by a particular clonal group of serogroup A, identified by multilocus enzyme electrophoresis (MEE) as subgroup III-1, occurred in Nepal (1983 and 1984), Pakistan, and India (1985) (2) and may have caused earlier epidemics in China. In 1987, an outbreak of group A meningococcal disease caused by the same clonal group occurred in association with the annual Moslem pilgrimage to Mecca (Hajj) (3). At that time, Saudi Arabia implemented vaccination requirements for all entering pilgrims. The vaccine formulations vary; bivalent A/C vaccine or quadrivalent A/C/ Y/W135 vaccine (as licensed in the United States) is used.