The West Nile virus stays alive in nature by getting spread back and forth between birds and mosquitoes. Birds get WNV more often than any other living things. When a mosquito bites a bird that has WNV, the mosquito gets the virus. Then, if the mosquito bites a bird that does not have WNV, the mosquito can give that bird the virus. In this way, birds and mosquitoes give the virus to each other and keep it alive.