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

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 free-ranging 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.