First Human Cases of West Nile Virus Reported in Idaho

Two Idahoans have tested positive for West Nile virus. They represent the first, locally-acquired human infections to be reported in the state this year. A woman in her teens from Payette County in southwest Idaho, and an eastern Idaho man in his 30s from Bonneville County, have both tested positive for West Nile infections. Neither of the individuals required hospitalization.

West Nile virus is spread by the bite of an infected mosquito. Last year, West Nile virus was discovered throughout Idaho, infecting approximately 130 people and contributing to one death. Two years ago, Idaho led the nation with approximately 1,000 human infections, which contributed to 23 deaths. Dr. Leslie Tengelsen, Idaho Deputy State Epidemiologist, says no one can predict the intensity of mosquito activity and West Nile infections that might occur. “These two cases, which are hundreds of miles apart, remind us that West Nile virus is active across our state,” she says. “West Nile season is upon us, so it is important for people to protect themselves from the bite of mosquitoes. We know from experience that West Nile infection can cause severe illness in anyone, and is often more serious in people over the age of 50.”

West Nile virus does not generally spread from person-to-person or from infected animals to people. To protect themselves, people are advised to avoid mosquitoes when they are most active, between dusk and dawn. In addition, people should:

Cover up exposed skin when outdoors and apply DEET or other EPA-approved insect repellent to exposed skin and clothing. Follow instructions on the product label, especially for children;
Insect-proof their homes by repairing or replacing screens; and
Reduce standing water or change water weekly in bird baths or decorative ponds that provide mosquito breeding habitat.

West Nile virus does not usually affect most animals, including dogs and cats, but can cause severe illness in horses and certain species of birds. Although there is not a vaccine available for people, there are several vaccines available for horses. People are advised to contact their veterinarian about vaccinating their horses.

Certain birds adversely affected by West Nile virus include magpies, crows, raptors, ravens and jays. They frequently die from West Nile infections. The Idaho Department of Fish and Game will continue testing and documenting dead birds this season. People who find dead birds are asked to call their local Fish and Game office. Fish and Game is most interested in testing birds that have been dead for less than 48-hours.

During the summer, people are spending more time outdoors doing yard work or taking part in outdoor recreation opportunities. Tengelsen advises people to take precautions. “West Nile virus is active across our state so we all must do our part. We encourage people to reduce mosquito habitat around their homes by eliminating standing water,” she says. “By doing that and taking personal protective measures to avoid mosquito bites, we can fight the bite and enjoy the great Idaho outdoors.”

So far this year, 19 other states have reported West Nile activity to the Centers for Disease Control and Prevention. For more information about West Nile virus, please visit Westnile Idaho or the CDC website.