Prevalence of coccidia in domestic pigs in China between 1980 and 2019: a systematic review and meta-analysis.

ABSTRACT

BACKGROUND: Swine coccidiosis, a protozoan disease caused by coccidia, can result in diarrhoea and weight loss in piglets and even economic losses in the pig industry. Here, we report the first systematic review and meta-analysis of the prevalence of coccidia (including Eimeria spp. and Cystoisospora suis) in pigs in China. METHODS: Five databases (PubMed, ScienceDirect, Chinese Web of Knowledge, Wanfang, and Chongqing VIP) were searched and 50 studies (46,926 domestic pigs, 22 provinces) ultimately identified pertaining to the prevalence of coccidia infection from 1980 to 2019. We incorporated the effect size using the random-effects model in the "meta" package in R software and conducted univariate and multivariate meta-regression analyses using a mixed-effects model. RESULTS: The pooled prevalence rate of coccidia in pigs was 21.9%, including the C. suis infection rate of 9.1%. The highest prevalence of coccidia (39.6%) was found in northwest China, and this region also presented the lowest prevalence of C. suis (4.7%). In the subgroup analysis based on sampling year, the highest prevalence of coccidia was detected in 2001 or earlier (32.6%), whereas the lowest rate was found in 2012 or later (14.3%). An opposite trend was observed for C. suis (5.5% in 2000 or earlier vs 14.4% in 2000 or later). The prevalence of coccidia in extensive farming systems (29.5%) was higher than that in intensive farming systems (17.3%). In contrast, the point estimate of C. suis prevalence was lower in the extensive farming systems (5.1%) than in the intensive farming systems (10.0%), but the difference was not significant (P > 0.05). Among the four age categories, the highest total coccidia prevalence (26.2%) was found in finishing pigs, followed by suckling piglets (19.9%), whereas the highest prevalence of C. suis (14.9%) was observed in suckling piglets. CONCLUSIONS: Our findings suggest that coccidia infection in Chinese pigs is common, although the prevalence of C. suis in pigs does not receive sufficient attention. We recommend the rational use of anticoccidial drugs to avoid drug resistance and the development of preventive and control measures for C. suis to reduce the incidence of swine coccidiosis.