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West Nile virus


What is West Nile virus?

West Nile virus (WNV) is carried by mosquitoes and can infect humans, horses, and birds.

How can I get WNV?

Humans can only get the virus from the bite of an infected mosquito; the disease does not spread from other animals to humans, or from person to person.

What are the symptoms of WNV?

Most infections are mild, with fever and flu-like symptoms, but severe infections may cause encephalitis (inflammation of the brain), and rarely, death.

How can WNV be prevented?
  • Avoid mosquito bites.
  • Mosquito-proof your home by draining standing water where mosquitoes breed.
  • Help your community by reporting dead birds to reduce your risk for becoming sick.

Oregon Health Authority, Public Health Division works with local health departments, mosquito control districts and other agencies to detect and test for the presence of WNV.

Learn more:

Disease Reporting


What is required?

Health-care providers and clinical laboratories:

Health care providers and clinical laboratories are required to report cases and suspect cases of West Nile virus, and veterinarians are required to report horses with the appropriate clinical signs.

See the WNV testing and reporting page for more information.

Our disease reporting page provides general information on how to report and telephone numbers of local health departments.

WNV testing and reporting


West Nile virus statistics (pdf)  from the 2013 Oregon Communicable Disease Summary.

See Also