From genomics to surveillance, prevention and control: new challenges for the African meningitis belt.

An international conference was held in Niamey, Niger, in November 2005. It aimed at reviewing the current situation in the meningitis belt. This region stretches from Senegal to Ethiopia and is characterized by high levels of seasonal endemicity with large epidemics of meningococcal meningitis occurring cyclically, generally caused by N. meningiditis serogroup A. WHO currently recommends a reactive strategy based on rapid detection of epidemics, intervention with antibiotics to treat cases and mass vaccination with a meningococcal polysaccharide vaccine to halt the outbreak. Epidemiological patterns of the disease in Africa have been changing with the occurrence of outbreaks outside the meningitis belt and with the emergence of serogroup W135, which first caused an epidemic among Hajj pilgrims in 2000 and then a large-scale meningitis outbreak in Burkina Faso in 2002. Consequently enhanced laboratory surveillance and confirmation of the strain responsible for the outbreak are required. New rapid dipstick tests have been developed through a collaboration between Institut Pasteur and CERMES. They are designed for bedside diagnosis and detect meningococcal antigens present in CSF using immunochromatography. The treatment of meningococcal meningitis during epidemics is based on short-course, long-acting oily chloramphenicol. An alternative is the use of ceftriaxone, which is equally effective and can be used in pregnant women and infants. A low-cost, monovalent serogroup A meningococcal conjugate vaccine for large-scale use in Africa is under development. In spite of the emergence of W135 strains in the meningitis belt, N. meningiditis A continues to be the principal strain isolated during the epidemic seasons and elimination of outbreaks of N. meningiditis serogroup A can still be considered as the primary objective of a preventive vaccination strategy.