Meningococcal disease in Africa.

Neisseria meningitidis (the meningococcus) is responsible for endemic and meningococcal disease in Africa. Meningococci are placed into 12 serogroups based on their capsular polysaccharide antigens. Group-B meningococci are responsible for sporadic endemic disease. In the meningitis belt of sub-Saharan Africa, the large spreading epidemics which occur every 5-10 years are usually caused by group-A meningococci, with attack rates of 400-500/100,000 population. In the last epidemic, infection spread from the original meningitis belt to Kenya, Uganda, Rwanda, Zambia and Tanzania. Most cases of meningococcal disease are of meningitis and meningococcal septicaemia is a rare presentation except in South Africa. It is important to exclude meningococcal septicaemia since this carries the highest mortality (up to 75%). Treatment involves intravenous chloramphenicol (or intramuscular, oily chloramphenicol), a drug which is preferable to penicillin because penicillin-resistant meningococci have already emerged in Africa. Dexamethasone treatment of meningococcal meningitis is unproven and may even be deleterious in developing countries. Prevention of epidemic meningococcal disease could be achieved by mass vaccination with protein-conjugate, group-A and -C polysaccharides, but these new vaccines are likely to be expensive.