Study of a Localized Meningococcal Meningitis Epidemic in Burkina Faso: Incidence, Carriage, and Immunity

Background. To better understand localized meningococcal meningitis epidemics, we evaluated a serogroup A (NmA) epidemic in Burkina Faso by surveillance, carriage, and seroprevalence studies. Methods. During March-April 2006, cerebrospinal fluid samples from patients suspected to have meningitis in 3 epidemic villages were analyzed by culture or polymerase chain reaction. We assessed meningococcal carriage and serogroup-specific serum bactericidal antibody titers with baby rabbit complement (rSBA) in a representative population sample (N = 624; age range, 1-39 years). A serogroup A/C polysaccharide vaccine campaign occurred in parallel. Results. Cumulative incidence of Nm meningitis was 0.45% and varied among villages (0.08%-0.91%). NmA carriage prevalence was 16% without variation by vaccination status. NmA carriage and anti-NmA seroprevalence varied by village and incidence. In the 2 villages with highest incidence and seroprevalence, presence of rSBA titers >= 8 was associated with NmA carriage (odds ratio [OR], 9.33 [95% confidence interval {CI}, 1.90-45.91]) and vaccination <= 4 days earlier (OR, 0.10 [95% CI,.03-.32]). Visibly purulent or Nm meningitis was significantly associated with recent flulike symptoms and exposure to kitchen smoke (risk ratios >15). Conclusions. A surge of NmA carriage may be involved in the development of meningococcal epidemics and rapidly increase anti-NmA seroprevalence. Flulike infection and kitchen smoke may contribute to the strength of epidemics.