[Clonal expansion of Neisseria meningitidis W135. Epidemiological implications for the African meningitis belt].

Meningococcal meningitis occur as large epidemics in the "African meningitis belt" described by L. Lapeyssonnie. Neisseria meningitidis serogroup A, clone III-I, was involved in recent epidemics and immunization with A and C vaccine was therefore adequate. However, we report here the emergence of a new clone of N. meningitidis of serogroup W135 during the 2001 epidemics in Niger and in Burkina Faso and discuss the implications of this new epidemiological feature for future surveillance and vaccine strategies.