Toxoplasma gondii infection among sheep and goats in Iran: a systematic review and meta-analysis

Toxoplasmosis, a cosmopolitan parasitic infection caused by Toxoplasma gondii, is frequently found in meat-producing animals and human beings. This review and meta-analysis study was performed to evaluate the overall prevalence of T. gondii infection among sheep and goats in Iran. Data were systematically collected from 1977 to 2012 in Iran on the following electronic databases: PubMed, Google Scholar, Science Direct, Scopus, Web of Science, Magiran, Irandoc, IranMedex, and Scientific Information Database (SID). Additionally, abstracts of national scientific congresses and dissertations were included. A total of 34 articles in field of sheep and 18 articles about goat toxoplasmosis, totalizing to the examination of 14,372 sheep and 3,120 goats, reporting prevalence of toxoplasmosis from different regions of Iran fulfilled our eligibility criteria. The overall prevalence rate of toxoplasmosis in Iran was estimated to be 31% (95% confidence interval (CI) = 0.259825 to 0.352382) in sheep and 27% (95% CI = 0.140097 to 0.424782) in goats, respectively. There was no significant difference in infection rate between males and females among sheep (odds ratio (OR) = 1.002, 95% CI = 0.59 to 1.696) and goats (OR = 1.027, 95% CI = 0.685 to 1.541). Analysis revealed that infection rate in sheep over than 1 year old was 2.4 times more than that in less than 1 year old (OR = 2.396, 95% CI = 1.050 to 5.467). This systematic review and meta-analysis study revealed that infection is widespread in Iran. Further studies are required to improve strategies for controlling infection among flocks and consequently in human population.