Epidemiology of gastrointestinal nematodes of free-ranging chickens (Gallus gallus domesticus) in Africa: A systematic review and meta-analysis

Abstract

A systematic review and meta-analysis were conducted, and published estimates determined the pooled prevalence of gastrointestinal nematode parasites affecting free-ranging chickens in Africa. Peer-reviewed articles published between 1993 and 2024 were systematically searched and screened. Prevalence estimates based on 76 eligible articles showed that of the 74,789 freeranging chickens screened, 13,625 were infected with gastrointestinal nematodes with an overall pooled prevalence of 15% (95% CI: 13–18%). Twenty-seven nematode species were recorded, of which Ascaridia galli and Heterakis gallinarum were the commonly reported species. Southern Africa recorded the highest pooled prevalence (22%; 95% CI: 13–33%), and western Africa had the lowest (5%; 95% CI: 0–2%) despite recording the highest nematode species diversity. Tetrameridae had the highest family-level pooled prevalence of 46% (95% CI: 28–64%), and Spiruridae had the lowest 1% (95% CI: 0–3%). Most studies were conducted between the period 2014 and 2024; however, the highest pooled prevalence was observed between 1993 and 2002 (17%; 95% CI: 11–24%). The necropsy technique recorded the highest pooled prevalence (17%; 95% CI: 14–20%) compared to coproscopy (10%; 95% CI: 7–14%). The quality effects model revealed a high heterogeneity and publication bias among studies due to the diagnostic method used (P <0.05). This systematic review provided insightful information on the occurrence and potential burden of gastrointestinal nematode species of free-ranging chickens in Africa, highlighting the need for enhanced biosecurity and further research to safeguard their health, production, and food security of rural economies.