Prevalence and risk factors for oropharyngeal carriage of Neisseria meningitidis and circulating genogroups in eastern and southwestern Ethiopia

Abstract

Abstract Neisseria meningitidis is a leading cause of meningitis epidemics in the African meningitis belt. Where invasive meningococcal disease surveillance is limited, carriage studies can identify circulating sero/genogroups to inform vaccine policies. We aimed to estimate the prevalence, identify the circulating genogroups and risk factors for N. meningitidis carriage in Ethiopia. We conducted a random cross-sectional survey among residents of Health and Demographic Surveillance Systems in Kersa, eastern Ethiopia and Gilgelgibe, southwestern Ethiopia between February and May 2024. Posterior oropharyngeal swabs were collected and cultured for N. meningitidis . Genogroups and clonal complexes were determined using whole genome sequencing. Overall and age-stratified carriage prevalence were estimated, and risk factors identified by logistic regression. Of 2000 targeted individuals, 1966 provided analysable oropharyngeal samples. Bacteria were cultured from 574 participants, and 105 were confirmed as N. meningitidis. Overall carriage prevalence was 5.3% (95% CI: 4.4–6.4%), being 9.3% (95% CI: 7.6–11.3%) in Kersa and 1.7% (95% CI: 0.7–2.2%) in Gilgelgibe. Prevalence varied by age, being highest among 10-14-year-olds and lowest among 1–4-year-olds (c²=17.6, p = 0.014). The 105 cultures comprised 39 MenW (all Clonal Complex 11) 7 MenB, 5 MenE, 3 MenC, and 51 nongroupable. None were MenA. MenW: CC11 strains, linked to epidemics, predominated and MenA was not identified. Future prevention of meningococcal disease in Ethiopia may require a vaccine targeting multiple serogroups.