Serosurvey of West Nile virus in horses and detection of West Nile virus antigen in mosquitoes in Kaduna State, Nigeria.

West Nile virus (WNV) causes a mosquito-borne zoonotic disease of public health importance. The aim of this study was to determine the state of WNV infection in horses and detect the virus antigen in mosquitoes trapped in stables in Kaduna State Nigeria. The study was carried out in Kaduna State, Nigeria, and 368 horses were screened for the presence of antibodies against WNV using an IgG competitive enzyme-linked immunosorbent assay. Of the 368 samples tested, 331 (89.9%) were positive for WNV antibodies. Mosquitoes from the stables were tested for WNV antigen using a VectorTest kit, and of the 31 pools of adult mosquitoes tested, only 5 (16.1%) pools tested positive for WNV antigen. This finding showed that WNV infection has occurred in horses and that there is evidence of circulation of the virus by mosquitoes in Kaduna State, Nigeria.