Haemophilus influenzae type b meningitis in the state of Paraná, Brazil

OBJECTIVE: During the second half of 1996, the municipalities of Londrina and Curitiba (State of Paraná, Brazil) included Haemophilus influenzae type b (Hib) vaccine into their routine vaccination regimen, approximately 30 months before its introduction into the National Immunization Program. The present study aimed at verifying the incidence of meningitis caused by Hib among children in Londrina, Curitiba, and in the remaining municipalities of the State, before and after the introduction of this vaccine into the immunization program. METHODS: An observational and retrospective study was carried out. The study included all cases of Haemophilus influenzae type b meningitis recorded by the epidemiological surveillance system in Londrina and by the State of Paraná Health Secretariat between 1992 and 1999 among children aged less than 5 years. The incidence rates of Hib meningitis were calculated per 100,000 children aged less than five years. RESULTS: After the introduction of Hib vaccine, an important reduction in the incidence rate of Haemophilus influenzae type b meningitis was observed in Londrina (from 23.91 in 1996 to 2.79 in 1999). A Similar decrease was observed in Curitiba. In the remaining localities of the state, which had not introduced the vaccine till mid-1999, the incidence rate remained almost unchanged. CONCLUSION: Regular vaccination against Hib was effective in reducing the incidence rate of meningitis amongst children younger than five years in Londrina and Curitiba. In order to maintain this low incidence rate, adequate vaccination coverage and strict epidemiological surveillance should be guaranteed.