[Surveillance of Haemophilus Influenzae meningitis in children in France, 2001-2006].

Background: The implementation of Haemophilus influenzae b (Hib) vaccination program in France in 1993 resulted in a rapid and dramatic decrease of the Hib meningitis incidence in children. The aim of our study was to describe the residual Haemophilus influenzae (Hi) meningitis in the French paediatric population between 2001 and 2006.

Methods: The French Paediatric Infectious Diseases Group set up an active surveillance network to analyze the clinical and biological features of bacterial meningitis. We used these data to retrospectively study the risk factors, signs and symptoms, vaccination status, cerebrospinal fluid analysis, treatment and case fatality rate of Hi meningitis.

Results: Among the 2539 cases of bacterial meningitis reported in France between 2001 and 2006, 69 (2.7 %) were due to Hi. A mean number of 11.5 cases of Hi meningitis was reported annually (minimum 6, maximum 16). Among Hi meningitis cases, 36 strains were of serotype b, 8 were capsulated but not b (6 f, 1 e and 1 unknown serotype), 20 strains were not capsulated, and 5 were non studied. The mean age of the children was 30.3 months (median 13.8 months, range 3.3 months to 14.5 years). 41 % of children with Hib meningitis did not received any anti-Hib vaccine and 41 % did not followed the French recommendations for Hib vaccine.

Conclusion: Hi meningitis still occurs, and more than half is due to the b serotype. Among Hib cases, 14 % did not recieved any anti-Hib vaccine and 15 % received an incomplete vaccination schedule. Increase of vaccine coverage and use of an earlier booster dose at the age of 12 months could further improve the epidemiology of Hib meningitis. The immunity of children with Hib meningitis should be systematically studied in order to improve the comprehension of the pathophysiology of vaccine failure.