When people become infected with WNV, they are quite often asymptomatic, showing no signs of illness or disease. However, in some individuals an influenza-like illness often follows. In humans, the virus has an incubation period of 3 to 10 days. Therefore, symptoms may appear suddenly and are often characterized by high fever, headache, backache, fatigue, and nausea. There is no known treatment for persons infected with WNV nor is there a vaccine.
Most people recover from infection completely within two weeks.
Fatal cases are more prevalent in people greater than 50 years of age. When infected, humans are unable to pass the infection to uninfected mosquitoes or other humans. WNV in Birds Birds do not normally show any symptoms of WNV infection. Rather they serve as natural reservoirs of the virus and are able to pass the virus to feeding mosquitoes. However, some avian species appear to be susceptible to the virus, displaying varying degrees of infection.