Baseline Meningococcal Carriage in Burkina Faso before the Introduction of a Meningococcal Serogroup A Conjugate Vaccine

Abstract

The serogroup A meningococcal conjugate vaccine MenAfriVac has the potential to confer herd immunity by reducing carriage prevalence of epidemic strains. To better understand this phenomenon, we initiated a meningococcal carriage study to determine the baseline carriage rate and serogroup distribution before vaccine introduction in the 1-to 29-year old population in Burkina Faso, the group chosen for the first introduction of the vaccine. A multiple cross-sectional carriage study was conducted in one urban and two rural districts in Burkina Faso in 2009. Every 3 months, oropharyngeal samples were collected from >5,000 randomly selected individuals within a 4-week period. Isolation and identification of the meningococci from 20,326 samples were performed by national laboratories in Burkina Faso. Confirmation and further strain characterization, including genogrouping, multilocus sequence typing, and porA-fetA sequencing, were performed in Norway. The overall carriage prevalence for meningococci was 3.98%; the highest prevalence was among the 15-to 19-yearolds for males and among the 10-to 14-year-olds for females. Serogroup Y dominated (2.28%), followed by serogroups X (0.44%), A (0.39%), and W135 (0.34%). Carriage prevalence was the highest in the rural districts and in the dry season, but serogroup distribution also varied by district. A total of 29 sequence types (STs) and 51 porA-fetA combinations were identified. The dominant clone was serogroup Y, ST-4375, P1.5-1,2-2/F5-8, belonging to the ST-23 complex (47%). All serogroup A isolates were ST-2859 of the ST-5 complex with P1

Seasonality of meningitis in Africa and climate forcing: aerosols stand out

“…Even with appropriate treatment, the mortality rate fluctuates around 10 per cent, and 10-15% of survivors suffer long-term neurological sequelae [7]. Asymptomatic carriage is common, which most often does not lead to the consecutive development of the illness [8,9]. Despite a strong seasonality, the determinants of meningitis dynamics are still poorly understood.…”

Carriage of Neisseria lactamica in 1- to 29-Year-Old People in Burkina Faso: Epidemiology and Molecular Characterization

“…To eliminate meningococcal epidemics in the meningitis belt, an affordable serogroup A conjugate vaccine, MenAfriVac, was first introduced in a country-wide mass vaccination campaign in Burkina Faso in December 2010 (10,24,25) after a large-scale safety study had been conducted in the whole district of Kaya in September 2010. The impact of MenAfriVac vaccination on meningococcal carriage was evaluated in a large carriage study performed before and up to 13 months after mass vaccination (21,22). In the course of that study, all lactose-fermenting Gram-negative diplococci were registered and some were kept for further investigation.…”

Strategies for the Prevention of Meningitis

“…The ability to adhere to or penetrate the mucosa, or to survive and multiply in blood or infect organs (especially the brain) are commonly-recognized virulence factors that, like epidemiology, may differ among strains, serogroups or types of encapsulated bacteria within a species (1,5,24,(28)(29)(30)(31)(32). Susceptibility to disease or asymptomatic carriage may coincide or occur in distinct population groups (Table 4).…”

“…Maternal colonization with Group B streptococcus, disease in infants (1,5,16,20,(22)(23)(31)(32) Ideally, definitive laboratory tests would rapidly confirm or exclude bacterial meningitis, determine the organism and identify its pattern of antibiotic susceptibility. Unfortunately, diagnosis of bacterial meningitis in the absence of a positive culture remains at best imprecise, despite numerous algorithms and putative biomarkers (Table 5).…”