Meningitis epidemics in Africa: a brief overview.

Every year, meningococcal meningitis causes thousands of deaths within the meningitis belt in sub-Saharan African countries. Large epidemic waves occur with a periodicity of 5-12 years. The waves do correspond to molecular changes in the expression of capsular or subcapsular antigens, which allow the bug to spread in susceptible populations. Serogroup A remains the major killer, even if in 2002, serogroup W135 ST-11 emerged in Burkina Faso, causing an important epidemic. However, the surveillance in the following years has showed a decrease in the W135 incidence and a clear predominance of serogroup A. Moreover, a new serogroup A strain belonging to ST-2859 seems to emerge and does represent a new threat for the coming seasons. In a vaccine perspective, and especially in the context of the development of an A conjugate vaccine; it is the key to strengthen the surveillance systems and to include molecular epidemiology as a tool for monitoring the molecular evolution of Neisseria meningitidis in Africa.