Seroprevalence and risk factors of Neospora caninum infection in cattle in China from 2011 to 2020: A systematic review and meta-analysis

Neosporosis is a worldwide infectious disease caused by the obligate intracellular parasite protozoan Neospora caninum (N. caninum), which has a heteroxenous life cycle and affects a wide range of warm-blooded animals, especially canines and cattle. Here, a meta-analysis was conducted to assess the overall seroprevalence and potential risk factors for N. caninum infection among cattle in China. The VIP Chinese Journal Databases (VIP), PubMed, WanFang, China National Knowledge Infrastructure (CNKI), and ScienceDirect databases were employed for a comprehensive search for relevant studies published from 2011 to 2020. A random-effects model was used to calculate the pooled seroprevalence estimated with 95% confidence intervals. The pooled N. caninum seroprevalence in cattle was estimated to be 12.2%. The highest seroprevalence of N. caninum infection in cattle was in Southern China (20.9%), while the lowest seroprevalence was in Northwest China (9.4%). The seroprevalence of N. caninum in the sub-group 2016 or later (10.2%) was lower than that in 2012-2015 (20.7%) and before 2012 (17.2%). Yaks were the least infected species of cattle (7.3%; Yellow cattle 18.1%; Buffalo 7.8%; Dairy cattle 21.5%). Cattle aged > 5 years had higher seroprevalence (20.7%) than that aged 3-5 years (10.7%) and < 3 years (14.2%). In season subgroups, the lowest N. caninum seroprevalence was found in summer (21.3%). Free ranging cattle had a 27.2% seroprevalence of N. caninum, which was higher than 7.8% in stall-feed cattle. The seroprevalence of N. caninum in female (22.6%) cattle was higher than in males (13.4%). Meanwhile, the prevalence was higher as increased parity and abortion. The results indicated that N. caninum infection in cattle was widely distributed in China. We recommend that more attention should be paid to the management of sanitary conditions for breeding in the areas with rich and warm water sources. In addition, it would appear to be prudent and feasible to selectively cease breeding for N. caninum seropositive animals in herds with low prevalence and farmers should not feed aborted fetuses to dogs on farm.