A systematic review and meta-analysis of population-based anthrax prevalence in Africa with a one health narrative synthesis of outbreak surveillance.

BACKGROUND: Anthrax remains a persistent public health, veterinary, and ecological challenge in Africa, sustained by fragmented surveillance systems characterized by underreporting, limited diagnostic capacity, and weak cross-sectoral coordination. The absence of integrated surveillance across human, livestock, wildlife, and environmental interfaces constrains accurate burden estimation and timely outbreak response.

METHODS: We conducted a systematic review and meta-analysis following PRISMA guidelines to synthesize available evidence on anthrax epidemiology in Africa. Studies published between January 2000 and February 2025 were identified from PubMed and Web of Science. Observational studies reporting primary epidemiological data in humans, livestock, wildlife, or environmental samples were eligible. Quantitative synthesis was restricted to cross-sectional studies reporting extractable prevalence data. Pooled estimates were generated using a logit-transformed random-effects model (REML), with heterogeneity assessed using I 2 and τ2 statistics. Studies not meeting meta-analytic criteria were synthesized narratively within a One Health framework.

RESULTS: Ten cross-sectional studies comprising 19,955 samples and 2,079 confirmed anthrax cases were included in the meta-analysis. The crude aggregated prevalence was 9.88% (95% CI: 9.46%-10.30%). The pooled prevalence from the logit-transformed random-effects model was 20% (95% CI: 8%-44%). Substantial heterogeneity was observed (I 2 = 98.2%), indicating marked epidemiological variability across ecological settings, host populations, and surveillance systems. Narrative synthesis further highlighted wildlife outbreaks and environmental persistence of Bacillus anthracis, though such studies remain comparatively scarce.

CONCLUSION: The available evidence on anthrax in Africa is limited, geographically uneven, and highly heterogeneous. The pooled estimate should therefore be interpreted as a summary measure of reported prevalence rather than a precise continental burden estimate. These findings underscore persistent transmission within fragmented surveillance systems and support strengthened One Health-based approaches integrating human, animal, wildlife, and environmental health sectors to improve surveillance, early detection, and coordinated response across Africa.