A systematic review and meta-analysis of the epidemiology of bovine viral diarrhea virus (BVDV) infection in dairy cattle in China.

Bovine viral diarrhea virus (BVDV) infection causes significantly economic losses to cattle industry worldwide, also including China. The epidemiological prevalence of infection associated with BVDV in dairy cattle has not been systematically assessed in China. Therefore, we undertook this study to evaluate prevalent of BVDV infection. We conducted a systematic review and meta-analysis of data from papers on the BVDV incidence and prevalence in dairy cattle in China by searching China Science and Technology Journal Database, China National Knowledge Infrastructure (CNKI), Wan Fang Database and PubMed for publication from March 2003 to March 2018. The 41 studies reporting the prevalence of BVDV in cattle in China were selected upon our inclusion criterion. The pooled BVDV prevalence in dairy cattle in China was estimated to 53.0% (95% CI 40.2-65.7) based on the data obtained from the 27,530 cows tested using serological or virological assay in the qualified papers published during the periods (χ² = 51,861.0, I = 99.9%). The highest BVDV positive rate in dairy flocks reached 90.0% in Fujian province of China, followed by Shaanxi (88.9%) and Shandong (83.3%). The prevalence in the six administrative districts of China was validated to be highly variable (25.7%-72.2%) and reached 72.2% in dairy cattle flocks of Northern China. Besides, the BVDV-RNA positive rate was estimated 27.1% (95% CI 17.3-37.0) based on 6 studies, comparatively, the pooled BVDV seroprevalence based on 35 studies was about 57.0% (95% CI 44.4-69.5) in China. This systematic review and meta-analysis firstly established an estimated prevalence of BVDV in dairy herds in China, indicating that the BVDV infection is escalating, though there is a bias in the number of studies between 2003-2009 and 2010-2018 timescales. This study may help understand the status of BVDV infection in dairy herds in China. Further extensive and comprehensive investigation is recommended, and effective intervention measures for preventing and controlling BVDV spread in dairy herds should be deployed, especially herds that have been exposed to BVDV.