Seroprevalence and associated risk factors of Porcine Reproductive and Respiratory Syndrome virus at herd levels in four provinces of Vietnam

AbstractBiosecurity measures are critical for protecting pig health; however, medium- and small-scale farmers in Vietnam do not always use these practices. This study performed a cross-sectional investigation of Porcine Reproductive and Respiratory Syndrome virus (PRRSV) seroprevalence in healthy pigs without PRRSV vaccination from four provinces in Vietnam from 2015 to 2017 and analyzed risk factors associated with PRRSV serological status at herd levels. A total of 1202 serum samples from 564 pig households were collected. True PRRSV seroprevalence at the animal and herd levels was 19.91% (95% CI: 17.54–22.50) and 20.59% (95% CI: 17.17–24.48), respectively. Pig farms, which used local feed grains and kitchen waste (OR = 2.18; P = 0.002), introduced newly purchased pigs without isolation (OR = 2.12; P = 0.007), or purchased pigs from local wholesale markets (OR = 3.48; P = 0.000), were associated with a higher risk of PRRSV seroprevalence. Those risk factors had positive interaction effects on the prevalence of PRRSV antibodies at herd levels (P = 0.000). The information on the evidence of PRRSV seroprevalence and risk factors is a valuable resource to improve awareness of the potential PRRSV transmission for farmers and veterinary services. Biosecurity education for pig owners and surveillance strategies on healthy pig populations will help significantly reduce the health risks of pig farms, especially small and medium pig farms, and minimize the economic effects of PRRS as well as other infectious diseases.