Abstract
Bovine leukemia virus (BLV) is horizontally transmitted among cattle through infected blood. This 3-year field study (2013-2016) aimed to confirm the potential of the blood-sucking stable fly as a risk factor of BLV transmission and to determine the efficacy of vector control on preventing the transmission of BLV. The BLV-positive conversion rate during summer was higher than that during winter in a model dairy farm, where many stable flies were observed during the summer. After fly nets were fixed onto the barn to prevent fly invasion, the BLV-positive conversion rate during the summer was significantly decreased compared with that in the absence of fly nets (P<0.01). These findings suggest that vector control using a fly net may inhibit BLV transmission.