Bacterial Meningitis in Brazil: Baseline Epidemiologic Assessment of the Decade Prior to the Introduction of Pneumococcal and Meningococcal Vaccines

Abstract

Background: Bacterial meningitis is associated with significant burden in Brazil. In 2010, both 10-valent pneumococcal conjugate vaccine and meningococcal capsular group C conjugate vaccine were introduced into the routine vaccination schedule. Haemophilus influenzae type b vaccine was previously introduced in 1999. This study presents trends in demographics, microbiological characteristics and seasonality patterns of bacterial meningitis cases in Brazil from 2000 to 2010.

Methods and findings: All meningitis cases confirmed by clinical and/or laboratory criteria notified to the national information system for notifiable diseases between 2000 and 2010 were analyzed. Proportions of bacterial meningitis cases by demographic characteristics, criteria used for confirmation and etiology were calculated. We estimated disease rates per 100,000 population and trends for the study period, with emphasis on H. influenzae, N. meningitidis and S. pneumoniae cases. In the decade, 341,805 cases of meningitis were notified in Brazil. Of the 251,853 cases with defined etiology, 110,264 (43.8%) were due to bacterial meningitis (excluding tuberculosis). Of these, 34,997 (31.7%) were due to meningococcal disease. The incidence of bacterial meningitis significantly decreased from 3.1/100,000 population in 2000-2002 to 2.14/100,000 in 2009-2010 (p<0.01). Among cases of meningococcal disease, the proportion of those associated with group C increased from 41% in 2007 to 61.7% in 2010, while the proportion of group B disease progressively declined. Throughout the study period, an increased number of cases occurred during winter.

Conclusions: Despite the reduction in bacterial meningitis incidence during the last decade, it remains a significant healthcare issue in Brazil. Meningococcal disease is responsible for the majority of the cases with group C the most common capsular type. Our study demonstrates the appropriateness of introduction of meningococcal vaccination in Brazil. Furthermore, this study provides a baseline for future evaluation of the impact of the vaccines introduction in Brazil and changes in disease epidemiology.

Figure 1. Proportion of bacterial meningitis cases notified to SINAN in Brazil from 2007 to 2010 by criteria used for case confirmation, according to pathogen.

Antigen detection methods include latex agglutination, counterimmunoelectrophoresis (CIE) and polymerase-chain reaction (PCR).

Figure 2. Proportion of bacterial meningitis cases notified to SINAN in Brazil from 2000 to 2010 by age group, according to the pathogen.

Figure 3. Monthly incidence rates of meningitis due to N. meningitidis, S. pneumoniae and H. influenzae per 100,000 population, by age-group, in Brazil, 2000 to 2010.

Panel A: All age groups combined, Panel B: Children aged 0 to 23 months.

Figure 4. Distribution of meningococcal disease cases by capsular subgroup (n = 11,037) in Brazil, 2007 to 2010.