The West Nile virus is a mosquito-borne virus that can cause mild-to-severe illness in humans and other animals. Mosquitoes become infected with West Nile virus when they feed on infected birds that carry the virus in their blood. Crows, blue jays and raven are particularly susceptible to the disease and can be a good indicator for the presence of the virus, said Laura Bauman, epidemiologist for the county.
