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West Nile virus


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

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

To prevent WNV:

  • Avoid mosquito bites.
  • Mosquito-proof your home by draining standing water where mosquitoes breed.
  • Help your community by reporting sick or 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, clinical laboratories and veterinarians:

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.


West Nile virus statistics (pdf)
from the 2015 Oregon Communicable Disease Summary.

See Also