Bovine neosporosis in Iran: A systematic review and meta-analysis

Neospora caninum is an apicomplexan parasite with worldwide distribution, which primarily causes disease in dogs and cattle. It has been recognized as an important cause of epidemic and endemic abortion in cattle around the world. There is no study to demonstrate the country level picture of the disease in Iran and estimate the extent of the problem, quantitatively. Therefore, the aim of the present study was to systematically review the observational studies on bovine neosporosis in Iran and estimate an overall serologic prevalence of the infection in the cattle population. Search for all published reports on N. caninum in Iran was conducted from inception until September 2018. Major English (PubMed, Scopus and Science Direct) and Persian (IranDoc, SID, Iranmedex, and Magiran) electronic database sources were used for this study. After removing duplicated articles, 128 documents remained. Unrelated articles (89) were excluded after primary screening and 39 articles were evaluated for eligibility. Finally, 37 studies from 33 articles were recognized as eligible and were included in the present work. The author screened the studies and extracted the data twice, carefully. Based on the meta-analysis, the overall serologic prevalence of N. caninum in 10,967 cattle with 2619 positive ones was 23.6 % with 95 % CI: 19.8-27.9 %. The random effect model was used for meta-analysis because the Cochran Q value (795.10, df = 36, P < 0.001) and Higgins index (I² = 95.47 %) showed statistically significant heterogeneity. In subgroup meta-analysis, abortion status of the animal and geographical location of the study showed significant association with serologic prevalence, while age and breed did not have significant associations. No publication bias was detected, and sensitivity analysis showed stability of the overall estimate after excluding any individual study. It could be concluded that N. caninum is widespread in cattle population in Iran and the time is right to implement national level educational and control programs for it.