Efficacy of haemophilus influenzae type B vaccine and its impact on the representation of causative agents of bacterial meningitis in children

Abstract

Objective - Research was undertaken with the aim of analyzing the frequency of causes of bacterial meningitis (BM) in children before and after introduction of the conjugate vaccine against Haemophilus influenzae type b (Hib vaccine), and to analyze the age of patients and disease outcome.

Materials and methods - Data from the medical records of patients, age 1 month to 14 years, who were treated for BM at the Infectious Diseases Clinic Tuzla, in the period from 01.05.1999 to 30.06.2009 were analyzed as a retrospective cohort study. In relation to the introduction of the Hib vaccine the patients were divided into prevaccinal and postvaccinal periods.

Results - 140 children were treated for BM. The most common pathogens were Haemophilus influenzae (13.6%), Neisseria meningitidis (8.6%) and Streptococcus pneumoniae (5.7%). In the prevaccinal period there were 94 and in the postvaccinal 46 children (13 of them had been vaccinated). The number of BM cases decreased from 17.1 (prevaccinal period) to 10.2 (postvaccinal period) per year. The number of children hospitalized with BM caused by Neisseria meningitidis significantly decreased in the postvaccinal period (Fisher’ exact test, p=0.009), and Streptococcus pneumoniae was the most common cause of BM in the postvaccinal period (Fisher’ exact test, p=0.015). The frequency of Haemophilus influenzae as a cause of BM also significantly decreased in the postvaccinal period (Fisher’ exact test, p=0.034). Eleven children were under one year, and eight children were from one to five years of age. Three children died.

Conclusion - The most common causes of BM in children aged 1 month to 14 years were Haemophilus influenzae, Neisseria meningitidis and Streptococcus pneumoniae. After the introduction of Hib vaccine the number of BM cases caused by Haemophilus influenzae and the total number of BM cases was reduced.