Skip to main content
U.S. flag

An official website of the United States government

How do I know if an animal is infected with West Nile Virus?

Signs of infection in wildlife, like in humans, can range from no symptoms to severe symptoms of neurologic illness. Commonly reported signs in animals include weakness, stumbling, trembling, head tremors, inability to fly/walk, and a lack of awareness that allows them to be easily approached and handled. These symptoms, however, can also have other causes. The only way to positively confirm West Nile Virus infection is by laboratory testing of the animal’s tissues.

Learn more: Vector-Borne Diseases