Neospora caninum in aborted bovine fetuses in Iran: a systematic review and meta-analysis

The aim of the present study is to systematically review the studies on Neospora caninum infection in aborted bovine fetuses in Iran. Search for all published reports on N. caninum in Iran was performed from inception until January 2020. Major English (PubMed, Scopus and Science Direct) and Persian (SID, Iranmedex, and Magiran) electronic database sources were used. Finally, 16 articles were assessed for eligibility and 12 articles comprising 20 independent studies were selected for inclusion in the meta-analysis. Due to the statistically significant heterogeneity (Q=149.12, df=19, P<0.001 and I2=87.26), the random effect model was used for meta-analysis. Prevalence of N. caninum infection in 1239 aborted bovine fetuses with 351 positive ones was 34.8% (95% CI: 26.5–44.0%). Sample size was categorized as < 50 and ≥ 50 and subgroup meta-analysis was performed to compensate for the loss of precision due to inclusion of small size studies. The result showed that overall prevalence of infection in the latter group (23.1%) is significantly lower than in the first category (45.7%). It may be suggested that the subgroup with large sample size would be more precise and conservative approximation of the infection at the country level. The present meta-analysis confirms the previous findings regarding the importance of N. caninum as a major abortion agent in cattle industry in Iran and the need for appropriate action toward prevention and control of this parasite.