Helminths of zoonotic importance in slaughtered food animals in Nigeria: a systematic review and meta-analysis.

Abstract

Knowledge of endemic helminths in a resource-limited country such as Nigeria is essential for their diagnosis, treatment and cost-effective control. In the present study, the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) guideline was employed to determine the prevalence and geographical distribution of zoonotic helminths in food animals slaughtered in Nigerian abattoirs between 1970 and 2016. Pooled prevalence estimate (PPE) was determined by the random-effects model while heterogeneity was evaluated using the Cochran's Q-test. Results from 42 eligible studies reported across 19 Nigerian states revealed 85,466 cases of zoonotic helminths from 3,771,832 slaughtered food animals. Overall PPE was 2.27% (95% confidence interval (CI): 2.25, 2.28). PPEs for sub-groups ranged between 0.51% (95% CI: 0.46, 0.56) and 18.05% (95% CI: 17.12, 19.01) across regions, hosts, study periods and diagnostic methods. Ascaris suum had the highest pooled prevalence of 25.46% (95% CI: 24.04, 26.92). Overall prevalence estimates for cestodes, nematodes and trematodes were 0.60% (95% CI: 0.59, 0.61), 21.51% (95% CI: 20.73, 22.30) and 1.86% (95% CI: 1.84, 1.87), respectively. A high degree of heterogeneity 99.97% (95% CI: 2.25, 2.28, P: 0.000) was observed. Zoonotic helminths were prevalent in slaughtered food animals, with higher prevalence estimates in the north-central region, pigs and during the last decade reviewed. Ascaris suum was the most prevalent helminth, while Fasciola gigantica had the widest geographical distribution. It is envisaged that the present information will help in the formulation of disease-control policies, encourage on-farm good agricultural practices, and adequate hygiene and sanitation in abattoirs and meat-processing plants, with the aim of protecting public health.