Prevalence and risk factors of bluetongue virus infection in sheep and goats in China: A systematic review and meta-analysis

Bluetongue is a viral disease transmitted by the bite of bloodsucking insects, which mainly occurs in sheep, goats, and cattle. Bluetongue is characterized by fever, leukopenia, and severe catarrhal inflammation of the oral and gastrointestinal mucosa. The present study aimed to evaluate and analyze the prevalence of bluetongue and its associated risk factors in sheep and goats in China. We collected 59 publications from 1988 to 2019 through searches at ScienceDirect, PubMed, the Chongqing VIP Chinese journal database, Wanfang database, and Chinese Web of knowledge. In these studies, a total of 123,982 sheep and goats across 7 regions of China were investigated, and the pooled prevalence of bluetongue in sheep and goats was 18.6%, as assessed using serological methods. The prevalence of bluetongue in Southern China was 30.3%, which was significantly higher than that in Northeastern China (4.7%). The prevalence of bluetongue between sheep (12.9%) and goats (28.1%) was significantly different (P < 0.05). Detection methods subgroup analysis showed that the prevalence of bluetongue was significantly higher (P < 0.05) in the others group (43.8%) than in the agar immunodiffusion (15.9%) and enzyme-linked immunosorbent assay groups (20.5%). In addition, different geographical factors (latitude range, longitude range, altitude range, average precipitation, and average temperature) could affect the prevalence. Our results suggested that bluetongue is widespread in sheep and goats, and sheep and goats in contact with insect media, such as Culicoides, or in a warm and humid environment, could have an increased prevalence of blue tongue disease. Animal disease prevention and control departments should focus on continuous monitoring of the bluetongue epidemic in sheep and goats to prevent and control outbreaks.