Tennessee's state veterinarian confirms a horse in Weakley County, Tenn. tested positive for West Nile Virus (WNV). The horse was euthanized due to the severity of the case.WNV is a mosquito-borne virus. Mosquitoes acquire WNV when they feed on infected birds and then spread the virus to people and other animals by biting them. While humans can be infected by WNV, the virus does not pass between people and horses, and horses do not transmit the infection to other horses. The only route of transm .