Gem State Roundup

West Nile Virus infections on the rise in Idaho, health officials say

By: - September 8, 2021 5:14 pm

West Nile Virus has been identified in 13 Idaho counties so far this year, including some that don’t normally report West Nile activity. (Courtesy of Pixabay)

The Idaho Department of Health and Welfare says there’s been an increase in positive West Nile Virus cases — in humans and horses — as well as more mosquito pools testing positive, especially in southwestern Idaho.

The virus has been identified in 13 Idaho counties this year, as well as the Salmon area of Lemhi County and Franklin County, which don’t often report West Nile Virus activity.

According to a health and welfare department press release, six human infections, all with severe neurologic disease, including one death, have been reported in Idaho as of Sept. 1. Only one human infection had been reported in Idaho last year by Sept. 1, according to the release

“The conditions are right for mosquitoes to transmit the virus now until a killing frost eliminates the mosquito populations,” said Dr. Leslie Tengelsen, Idaho state public health veterinarian in the Division of Public Health. “Idahoans should assume that WNV is a risk anytime and anywhere mosquitoes are active.“

Tengelsen she encourages Idahoans to “fight the bite” of mosquitoes to protect themselves, including wearing insect repellent, wearing protective clothing, and reducing or draining standing water on property where mosquitoes lay their eggs.

The department said the active period for the virus is usually August through September, but infections can be difficult to predict from year to year. In 2006, Idaho had more West Nile Virus illnesses than any other state, with almost 1,000 infections and 23 deaths. During more recent seasons, that activity has been extremely low, according to the department.

The virus is usually contracted from the bite of an infected mosquito and 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 old and older. The health department encourages Idaho residents to talk to a health care provider about testing for the virus if they experience symptoms after being bitten by mosquitoes.

To protect against infection, people should avoid mosquitoes, particularly between dusk and dawn when mosquitoes are most active. Other tips for preventing a West Nile Virus infection include:

  • 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.

The West Nile Virus 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 annual vaccines for horses.

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Christina Lords
Christina Lords

Christina Lords is the editor-in-chief of the Idaho Capital Sun and has been a professional journalist covering local and state government since graduating from the University of Idaho in 2009. A Pocatello native, Lords is a fifth-generation Idahoan who served as a reporter at the Moscow-Pullman Daily News and the Post Register in Idaho Falls and served as assistant editor for the Idaho Press in Nampa. She also led the Idaho Statesman in Boise for two years before turning to nonprofit journalism.