The Cascade County Weed and Mosquito Division has detected its first West Nile Virus positive mosquito samples of 2023.

Two WNV positive samples of adult Culex tarsalis mosquitos were collected from the northern and northwest city limits of Great Falls on Aug. 10, according to the Cascade City-County Health Department.

The samples were confirmed positive by the lab at the Montana Department of Public Health and Human Services in Helena on Aug. 14.

Sample near Simms tests positive for West Nile Virus; CCHD urges protection [2019]

Mosquito control treatments were applied in the affected areas on the evening of Aug. 10, and the Weed and Mosquito Division continues monitoring in those areas and throughout Cascade County, according to CCHD.

There have been no known human infections of WNV detected in Cascade County in 2023, according to CCHD, but residents are strongly encouraged to take steps to protect themselves.

Human case of West Nile Virus reported in Cascade County [2018]

The single best defense against WNV is bite prevention. To protect yourself, use the five Ds, according to CCHD:

• DEET – Apply repellent containing an EPA-registered active ingredient, such as DEET, and follow the directions on the package.
• DUSK and DAWN – This is when mosquitoes are most active. Try to avoid outdoor activities during these times.
• DRAIN STANDING WATER – Standing water is the perfect breeding ground for mosquitoes. Drain such areas around your home (gutters, pools, tires, buckets, water bowls, etc.).
• DRESS APPROPRIATELY – Wear long-sleeved shirts, long pants and socks.

The severity and symptoms of WNV can vary widely. About 80 percent of persons infected experience no symptoms, but up to 20 percent of infected persons can develop a mild illness called West Nile fever, according to CCHD.

The illness generally resolves itself without treatment, but dangerous brain infections such as encephalitis or meningitis can develop in one out of 150 people. Symptoms usually appear 3-14 days after exposure and may include headache, rash, high fever, stiff neck, mental confusion, muscle weakness, tremors, convulsions, coma, and paralysis, according to CCHD. Individuals who develop any of these symptoms should see their healthcare provider immediately.

Jenn Rowell

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