[Which vaccination strategies for African meningococcal meningitis?].

In 1963, Lapeyssonnie published a masterful description of the epidemiology of cerebrospinal meningococcal meningitis in the Sahel region of Africa (essentially due to the Neisseria meningitidis sero-group A): geographic spread (meningitis belt), seasonal cycle (dry and cool season). When a combined polyosidic AC vaccine became available in the early 1970s, a disease control strategy was defined along the lines of epidemiological surveillance, prophylaxis of lethality by early treatment of cases and reactive vaccination, since the polyosidic vaccine could not be included in the Expanded Programme on Immunization (EPI). Despite some success, this strategy has not led to the control of cerebrospinal meningococcal meningitis in Africa. Amongst the obstacles encountered are the difficulty to define at what point an out-break becomes an epidemic, gaps in epidemiological surveillance, unavailable vaccine doses, delayed and complex vaccination campaigns. At the end of the 1990s, controversy ensued: since reactive vaccination was fraught with so many problems, why not consider a strategy of preventive AC vaccination for high risk areas? But this controversy may well die out with the emergence of the present-day W 135 serogroup responsible for the first large scale epidemic in Burkina Faso in 2002. If this is confirmed, a polyosidic vaCcine containing the W 135 antigen would be required, pending the availability for Africa of a conjugate tetravalent ACYW135 vaccine which could be included in the EPI.