West Nile is a virus transmitted via infected mosquitoes. The most serious manifestation of West Nile Virus infection is fatal encephalitis (inflammation of the brain) in humans and horses, as well as mortality in certain domestic and wild birds. Some people who become infected with West Nile Virus do not have symptoms. For those who do, symptoms appear 5-15 days after a mosquito bite. Typically the symptoms include fever, headache, and a general feeling of illness.
View the New Mexico Department of Health's West Nile Virus Brochure.