[Epidemiological and control aspects of meningococcal meningitis epidemics in Africa].

Meningococcal meningitis epidemics are a major health problem in sub-saharan Africa where they account for thousands of deaths and cause morbidity in hundreds of thousands of people. Meningitis is caused by Neisseria meningitidis. In Africa, epidemic meningitis is primarily due to strains of serogroup A which are responsible for the largest and most recent epidemics. N. meningitidis serotype 4, serosubtype P1.9, clonal complex III-1 was introduced into Africa in 1987. Since then, epidemics spread through the Lapeyssonnie's meningitis belt to the south. Classically, the 6 months-30 years old age group is the group at highest risk of disease. Nevertheless, in recent epidemics caused by clonal complex III-1, high age-specific attack rate occurred in those aged 30 years and over. The objectives of epidemic control are the reduction of mortality and morbidity. Early detection of an emerging epidemic is based on the observation of an incidence rate above a cutoff value. Recently, the WHO has proposed a cutoff of 15 cases/100,000/week averaged over two weeks. Epidemic investigation must be as rapid as possible after detection. The different steps are: confirmation of the epidemic and the meningococcal aetiology, standard case definition and determination of the high risk population. During epidemics, in developing countries, simplified treatment protocols are justified and a single dose of long-acting chloramphenicol is a useful first-line treatment. The strategy most frequently used for the control of epidemics is mass vaccination after the start of the epidemic. This must be done as quickly as possible.(ABSTRACT TRUNCATED AT 250 WORDS)