Haemophilus influenzae, the second cause of bacterial meningitis in children in Madagascar

The Haemophilus influenzae b is one of the main germs causing bacterial meningitis in children in countries where the vaccine anti-Haemophilus influenzae b is not widely used. In Madagascar, no epidemiological study on this germ has been carried out. The objective of this research is to assess the role of Haemophilus influenzae meningitis in Antananarivo and to determine its epidemiological aspects and evolution. A multicentric study coordinated by the Institut Pasteur de Madagascar included all children less than 15 years old with infectious syndromes associated to a syndrome of meningial irritation and/or convulsion and/or coma. These children were admitted in the pediatric service of the three main hospitals in Antananarivo from June 1998 and June 2000. A lumbar puncture was performed on each child; the cerebrospinal fluid was set aside for cytobacterial and biochemical controls completed with an antimicrobial sensitivity testing and a soluble antigens research. Out of 160 case studies, the Haemophilus influenzae b arrives at the second place among the agents causing bacterial meningitis in children. This type of bacteria is the source of 32% of meningitis after the Streptococcus pneumoniae (34%). It affects 96 % of children less than two years old, with a maximal frequency before the age of one year. The lethality rate is 28.6% and the neurological sequelae were observed in 31.4% of patients. Haemophilus influenzae is sensitive to the third generation cephalosporins but shows high resistance to chloramphenicol (42%), amoxicillin (29%) and gentamicin (22%). The relatively high frequency as well as the high lethality rate caused by the Haemophilus influenzae b meningitis, affecting selectively the children under two years old, bring in the need to introduce the anti-Haemophilus influenzae b vaccine in the national vaccination program in Madagascar. This vaccine has proved to be efficient in many countries where it has been used. Furthermore, in the probabilistic treatment of bacterial meningitis in children, the third generation cephalosporins should be used in the first place.