Narrative review of methods and findings of recent studies on the carriage of meningococci and other Neisseria species in the African Meningitis Belt

OBJECTIVE:To review the findings of studies of pharyngeal carriageof Neisseria meningitidisand related species conducted in the African meningitis beltsince a previous review published in 2007. METHODS:PubMed and Web of Science were searched in July 2018 using the terms 'meningococcal OR Neisseria meningitidisOR lactamica AND carriageAND Africa', with the search limited to papers published on or after 1st January 2007. We conducted a narrative review of these publications. RESULTS:One hundred and thirteen papers were identified using the search terms described above, 20 of which reported new data from surveys conducted in an African meningitis beltcountry. These papers described 40 surveys conducted before the introduction of the group A meningococcal conjugate vaccine(MenAfriVacR ) during which 66 707 pharyngealswabs were obtained. Carriageprevalence of N. meningitidisvaried substantially by time and place, ranging from <1% to 24%. The mean pharyngeal carriageprevalence of N. meningitidisacross all surveys was 4.5% [95% CI: 3.4%, 6.8%] and that of capsulated N. meningitidiswas 2.8% [95% CI: 1.9%; 5.2%]. A study of households provided strong evidence for meningococcal transmission within and outside households. The introduction of MenAfriVac® led to marked reductions in carriageof the serogroup A meningococcus in Burkina Faso and Chad. CONCLUSIONS:Recent studies employing standardised methods confirm the findings of older studies that carriageof N. meningitidisin the African meningitis beltis highly variable over time and place, but generally occurs with a lower prevalence and shorter duration than reported from industrialised countries.