Epidemiological features of bacterial meningitis in adults and children

One million meningitis eases occur every year over the world: the incidence rate reaches 20/100000. Developing countries have the highest incidence and mortality rate; average mortality is 20%:less than 10% in developed countries; it can reach over 50% in some places, Sequela, especially deafness, are estimated at over 5%. In endemic regions H. influenzae (20 to 40% of the isolates) is one of the most common agent in children under 5 years of age, pneumococcus (15 to 30%) affects infants and elderly people; meningococcus is widespread, especially among young adults. Incidence varies a lot according to preexisting conditions, ethnic and social characteristics, seasons and regions. Meningococcus A and C strains are responsible for large epidemics in tropical countries and some outbreaks in mild climate countries. Third generation cephalosporins are now being used because an increasing number of H. influenzae strains are resistant to ampicillin. The high prevalence of beta-lactamin resistant pneumococcus is quite preoccupying. Hib vaccination in some developed countries is very promising and modifies the epidemiology of meningitis in children. Meningitis prevention is a good reason to develop vaccination programs. Improving data collection on meningitis and determining groups at risk would be useful for prevention policies.