Incidence, seasonality, age distribution, and mortality of pneumococcal meningitis in Burkina Faso and Togo

Abstract

Streptococcus pneumoniae causes a substantial proportion of meningitis cases in the African meningitis belt; however, few reports exist to quantify its burden and characteristics. We conducted population-based and sentinel hospital surveillance of acute bacterial meningitis among persons of all ages in Burkina Faso and Togo in 2002-2006. S. pneumoniae and other organisms were identified by culture, polymerase chain reaction, or detection of antigen in cerebrospinal fluid (CSF). Information was collected on 2843 patients with suspected acute bacterial meningitis. CSF specimens were collected from 2689 (95%) of the patients; of these 2689, 463 (17%) had S. pneumoniae identified, 234 (9%) had Haemophilus influenzae type b identified, and 400 (15%) had Neisseria meningitidis identified. Of the 463 cases of S. pneumoniae meningitis, 99 (21%) were aged <1 year, 71 (15%) were aged 1-4 years, 95 (21%) were aged 5-14 years, and 189 (41%) were aged >or=15 years (age was unknown for 9 [2%]). In Burkina Faso, the annual incidence rate of pneumococcal meningitis was 14 cases per 100,000 persons, with annual incidence rates of 77, 33, 10, and 11 cases per 100,000 persons aged <1 year, <5 years, 5-14 years, and >or=15 years, respectively. The case-fatality ratio for S. pneumoniae meningitis was 47% (range for age groups, 44%-52%), and 53% of deaths occurred among those aged >5 years. S. pneumoniae meningitis had an epidemic pattern similar to that of N. meningitidis meningitis. Of 48 isolates tested for serotype, 18 were from children aged <5 years; of these 18, 3 isolates (17%) each were serotypes 1, 2, and 5, and 5 isolates (28%) were serotype 6A. The 7-, 10-, and 13-valent pneumococcal conjugate vaccines would cover 6%, 39%, and 67% of serotypes identified among children aged <5 years, respectively. Of the 30 serotypes identified for patients aged >or=5 years, 18 (60%) were serotype 1, whereas no other serotype constituted >10%. The 7-, 10-, and 13-valent vaccines would cover 7%, 70%, and 77% of serotypes. Epidemic pneumococcal meningitis in the African meningitis belt countries of Burkina Faso and Togo is common, affects all age groups, and is highly lethal. On the basis of a modest number of isolates from a limited area that includes only meningitis cases, 7-valent pneumococcal conjugate vaccine might have only a limited and short-term role. By contrast, the proposed 10- and 13-valent vaccines would cover most of the identified serotypes. To better inform vaccine policy, continued and expanded surveillance is essential to document serotypes associated with pneumonia, changes in serotype distribution across time, and the impact of vaccine after vaccine introduction.