[Epidemiology and control of bacterial meningitis in children less than 1 year in Niamey (Niger)].

Abstract

A bacteriological and epidemiological study of bacterial meningitis occurring in infants under one year of age was performed from September 1981 to June 1997 in Niamey, a city of 575,000 residents, located within the African meningitis belt. Cases of meningitis were defined either by culture of the cerebrospinal fluid (CSF), specific antigen agglutination, staining or cell counts of the CSF. Over the 16 years involving both epidemic and non epidemic periods, 1,481 infant's CSF were analysed, representing 20% out of the total CSF samples. The average of annual incidence rates was 511.4 cases per 100,000 infants under one year. Haemophilus influenzae b represented 35.1% of the cases, Streptococcus pneumoniae 26.3% and Neisseria meningitidis 17.6%. The other bacteria represented 5.5% and, for 15.5% out of the analysed CSF, the causative agent was not identified. The average annual mortality rate was 146.9 deaths for 100,000 infants under one year. The specific case fatality rates were 43% for H. influenzae b, 58.9% for S. pneumoniae and 17.8% for N. meningitidis. This study showed that in Niamey, as in the rest of the meningitis belt, S. pneumoniae and H. influenzae b were the main causes of bacterial meningitis occurring in infants under one year. However, the specific incidence of N1 meningitidis was identical for every age group between 0 and 20 years, and varied from 45 per 100,000 during non epidemic year to 550 per 100,000 during epidemic year. Immunisation with conjugate vaccines, particularly anti-Haemophilus vaccine appears to be the best preventive measure. The systematic use of ceftriaxone in infants, during meningococcal meningitis either epidemics or not, is highly recommended.