RESUMEN
Control of meningitis epidemics is based on early case detection followed by mass campaigns of immunisation. However, this strategy showed severe inadequacies during recent outbreaks in Africa. In Niamey, Niger, meningococcal vaccinations began in 1978 and detailed bacteriological and epidemiological surveillance of meningitis started in 1981. When vaccine coverage rates were higher than 50%, the prevalences of Neisseria meningitidis A meningitis were low in Niamey, although there was a concurrent epidemic in rural Niger. A massive outbreak of meningitis in Niamey in 1994-1995 followed a 6-year period during which the mean rate of vaccine coverage remained < 25%. The data indicate that, in the meningitis belt, preventive immunization should avoid a great number of deaths and be less expensive than mass immunisation campaigns performed after epidemics have begun.