Owyhee County reports Idaho’s first West Nile virus infections in humans this year

DHW Communications

Idaho’s first locally-acquired human West Nile virus (WNV) infections this year have been identified among two Owyhee County residents. Both residents were over the age of 50. One was diagnosed with West Nile fever and the other was identified through blood donor screening. These are the first human cases of WNV infection in Idaho for 2020. 

So far this year, WNV activity has been detected in six southwest counties.

“The detection of West Nile virus-positive mosquitoes has increased significantly during the last few weeks and we strongly encourage Idahoans to fight the bite of mosquitoes to protect themselves and their families,” said Dr. Leslie Tengelsen, state public health veterinarian. “Confirmation of human infection makes it increasingly important for all of us to take protective measures. This includes wearing insect repellent and protective clothing in addition to reducing standing water around our gardens and homes where mosquitoes can lay their eggs.”

Last year, 13 human WNV infections were reported statewide. WNV activity was reported in 12 counties in mosquitoes, horses, and people. The impact WNV has from year-to-year is difficult to predict. In 2006, Idaho had more WNV illnesses than any other state, with almost 1,000 infections and 23 deaths.

WNV is usually contracted from the bite of an infected mosquito; it is not spread from person-to-person through casual contact. Symptoms of infection often include fever, headache, body aches, nausea, and sometimes swollen lymph glands or a skin rash. Infection can result in severe illness, especially in people 50 years and older. Talk to your healthcare provider about testing for WNV.

To protect against WNV infection, people should avoid mosquitoes, particularly between dusk and dawn when mosquitoes are most active. In addition, everyone should:

  • Cover up exposed skin when outdoors and apply DEET or other EPA-approved insect repellent to exposed skin and clothing. Carefully follow instructions on the product label, especially for children.
  • Insect-proof your home by repairing or replacing screens. 
  • Reduce standing water on property; check and drain toys, trays or pots outdoors that can hold water.
  • Change bird baths, static decorative ponds, and animal water tanks weekly to reduce suitable mosquito habitats.

WNV does not usually affect domestic animals but can cause severe illness in horses and some species of birds. Although there is no vaccine for people, there are several vaccines for horses, which should be vaccinated annually.

For more information, please visit www.westnile.idaho.gov.



Niki Forbing-Orr
Public Information Manager
Idaho Department of Health and Welfare
(208) 334-0668

Katrina Williams
Public Information Officer
Southwest District Health
(208) 899-1268