An epidemiological synthesis of emerging and re-emerging zoonotic disease threats in Cameroon, 2000–2022: a systematic review

Introduction: Population factors such as urbanization, socio-economic, and environmental factors are driving forces for emerging/re-emerging zoonotic diseases in Cameroon. To inform preparedness and prioritization efforts, this study mapped out epidemiological data (including prevalence) of zoonotic diseases occurring in Cameroon between 2000 and 2022 by demographic factors. Methods: Following the PRISMA guidelines, a protocol was registered in the PROSPERO database (CRD42022333059). Independent reviewers searched the PubMed, Embase, CINAHL, Cochrane, and Scopus databases on May 30, 2022 for relevant articles; duplicates were removed, and the titles, abstracts, and full texts were screened to identify eligible articles. Results: Out of 4142 articles identified, 64 eligible articles were retrieved in the database search and an additional 12 from the cited literature (N = 76). Thirty-five unique zoonoses (viral, bacterial, and parasitic) were indexed, including Cameroon priority zoonoses: anthrax, bovine tuberculosis, Ebola and Marburg virus disease, highly pathogenic avian influenza, and rabies. The number of studies varied by region, ranging from 12 in the Far North to 32 in the Centre Region. The most reported were as follows: brucellosis (random-effects pooled estimate proportion (effect size), ES 0.05%, 95% confidence interval (CI) 0.03–0.07; n = 6), dengue (ES 0.13%, 95% CI 0.06–0.22; n = 12), avian and swine influenza virus (ES 0.10%, 95% CI 0.04–0.20; n = 8), and toxoplasmosis (ES 0.49%, 95% CI 0.35–0.63; n = 11), although I² values were greater than 75%, thus there was high inter-study heterogeneity (P < 0.01). Conclusions: This understanding of the distribution of emerging and re-emerging zoonotic threats in Cameroon is vital to effective preventive and resource prioritization measures.