West Nile Virus

What Is It?

  • West Nile Virus (WNV) is a viral disease of birds, especially corvids, commonly found in Africa, West Asia, the Middle East, Europe and most recently North America.

Why Is It Important?

  • WNV is a mosquito-borne virus that can cause disease in both humans and animals.
  • Humans and horses are dead end hosts for the disease, meaning that they are susceptible to the virus, can develop severe illness or die from the disease, but cannot transmit the virus to other animals or mosquitoes.
  • In humans, infection with West Nile Virus can vary from no apparent illness to mild illness (headaches, fever, body aches); and rarely can cause serious illness or death.

Where Is It Located?

  • WNV occurs throughout the continental United States and eastern and southern Canada. The disease is most commonly found during summer and fall months when mosquitoes are present.
  • View this website to see current West Nile Virus reports in various states: USGS West Nile Virus Disease Map.

Who Is Affected By It?

  • West Nile Virus is transmitted between birds by some species of mosquitoes but primarily causes disease in corvids (crows, jays, and magpies).
  • West Nile Virus has been documented in domestic animals (horses, dogs, cats, llamas, alpacas and captive reindeer, mountain goats and alligators) and wild animals including reptiles, birds (especially corvids, sage grouse, hawks, owls and eagles), white-tailed deer and other small mammals.

How Does Infection Occur?

How Do I Keep Myself, My Family, and My Pets From Becoming Affected?

The easiest and best way to avoid West Nile Virus is to prevent mosquito bites.
  • Cover exposed skin when outdoors (long sleeves, long pants).
  • Apply insect repellent containing DEET.
  • Avoid outdoor activities at dawn and dust when mosquitoes are most active.
  • Eliminate standing water, clean birdbaths/ponds around residences where mosquitoes could breed.
  • Maintain intact window and door screens.
  • Regularly vaccinate horses, ponies and mules against West Nile Virus.

Reporting Dead Birds

Report or submit birds – especially crows, ravens, magpies, jays, hawks, owls and eagles – that have been dead less than 48 hours to Fish and Game regional offices for testing. Valuable information includes the type of bird, if known, and when and where it was found.
  • When handling a dead bird, use latex or rubber gloves or a plastic bag to prevent touching the bird. Birds should be placed into a plastic bag and then double bagged. Birds can be submitted fresh, refrigerated, or frozen to Fish and Game. Gloves should be discarded in the trash after use.
  • Disposing of Dead Birds: If West Nile virus is suspected, and dead birds are not going to be submitted for testing, they should picked up using latex or rubber gloves or a plastic bag to prevent touching the birds. Place the dead birds in a second plastic bag and dispose of them in the trash.

What Is Idaho Fish and Game Doing to Help Manage This Disease?

  • Working cooperatively with the Idaho Department of Health and Welfare and Idaho State Department of Agriculture to track dead birds and the occurrence of West Nile Virus in Idaho.
  • Collecting and testing samples from dead corvids, sage grouse and raptors for West Nile Virus.
  • Providing public education about West Nile Virus.
Sage Grouse Strut  
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Last Updated: July 16, 2013 
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