Global, Regional, and National Prevalence of Chlamydiosis in Small Ruminants: Systematic Review and Meta-Analysis

Abstract

A systematic review and meta-analysis were conducted to estimate the prevalence of chlamydiosis in small ruminants. The study included 133 publications that reported the presence of Chlamydia abortus in 109 and 74 studies in sheep and goats from 45 countries. The prevalence of chlamydiosis was estimated at global, regional, and national levels using meta-analyses of proportions. Meta-regression and cumulative meta-analyses were also performed. Globally, the prevalence of chlamydiosis in sheep and goats was estimated at 20.1% (95% CI: 17.8-22.4) and 14.4% (11.6-17.4), respectively. For sheep, chlamydiosis prevalence was heterogeneous at regional and national levels. South Asia had the highest prevalence (30.6%) and East Asia and Pacific the lowest (14.0%). Nationally, chlamydiosis was more prevalent in Romania, Hungary, and Germany (range 53.3-87.0%) compared to Costa Rica, Australia, and Zimbabwe (4.7-5.2%). Among goats, chlamydiosis prevalence was similar across regions (10.4-19.7%), but varied significantly among countries, 0.0% in Romania and Australia and 91.7% in Bosnia and Herzegovina. In both species, sample size, number of diagnostic techniques, and latitude were significant covariates. Prevalence varied widely in the first decades of publications before stabilizing. Our study found a high prevalence of chlamydiosis in small ruminants, with the pathogen being distributed globally but heterogeneously across countries.