Childhood meningitis in rural Gambia: 10 years of population-based surveillance

Background: The introduction in many countries of conjugate vaccines against Haemophilus influenzae type-b, Streptococcus pneumoniae , and Neisseria meningitidis has led to significant reductions in acute bacterial meningitis (ABM) in children. However, recent population-based data on ABM in sub-Saharan Africa are limited. Methods: Population-based surveillance for meningitis was carried out in a rural area of The Gambia under demographic surveillance from 2008 to 2017, using standardised criteria for referral, diagnosis and investigation. We calculated incidence using population denominators. Results: We diagnosed 1,599 patients with suspected meningitis and collected cerebrospinal fluid (n=1,121) and/or blood (n=1,070) from 1,427 (88%) of cases. We detected 169 cases of ABM, 209 cases of non-bacterial meningitis and 1,049 cases of clinically suspected meningitis. The estimated average annual incidence of ABM was high at 145 per 100,000 population in the <2-month age group, 56 per 100,000 in the 2-23-month age group, but lower at 5 per 100,000 in the 5-14-year age group. The most common causes of ABM were Streptococcus pneumoniae (n=44), Neisseria meningitidis (n=42), and Gram-negative coliform bacteria (n=26). Eighteen of 22 cases caused by pneumococcal serotypes included in PCV13 occurred prior to vaccine introduction and four afterwards. The overall case fatality ratio for ABM was 29% (49/169) and highest in the <2-month age group 37% (10/27). The fatality rate was 8.6% (18/209) for non-bacterial meningitis cases. Conclusions: Gambian children continue to experience substantial morbidity and mortality associated with suspected meningitis, especially acute bacterial meningitis. Such severely ill children in sub-Saharan Africa require improved diagnostics and clinical care.