West Nile virus detected in four eastern Montana counties

West Nile virus has been detected in four eastern Montana counties: Blaine, Dawson, Prairie and Wibaux, the Montana Department of Public Health and Human Services reported Monday.

Six mosquito pools in the four counties tested positive for the virus, which the health department says is an early indicator that activity is increasing within the state.

Historically, Montana identifies the first human and/or horse WNV cases of the year within about two weeks of detecting WNV in mosquitoes.

Infections can occur in humans after a bite from an infected Culex mosquito. Increased risk of transmission to humans is expected to continue through October – or as long as mosquitoes are active in the state.

Most people who become infected with WNV will not experience symptoms, but 1 in 5 experience minor illness causing headache, rash, body aches, joint pains, fatigue, vomiting, and diarrhea. Fatigue and body aches may persist for weeks following infection.

About 1 in 150 human infections result in severe disease, referred to as neuroinvasive West Nile. Neuroinvasive West Nile can cause neurological symptoms including disorientation, stupor, coma, paralysis, vision loss, and convulsions. WNV can be fatal or lead to long-term neurological complications such as paralysis.

Currently, there is no vaccine or targeted medication for WNV in humans, aside from supportive care.

Horses can also be infected with WNV. Horse owners may contact their veterinarian to obtain an annual vaccine to protect against WNV.

To keep mosquitoes away from homes, it’s important to regularly empty standing water at least once per week. For items such as rain barrels, a screen can be applied to the opening to restrict mosquito access. Check out the 4 Ds of mosquito bite prevention below for other mosquito bite prevention tips.

The 4 Ds of Mosquito Bite Prevention:

1. DEET: Use insect repellent containing effective ingredients such as DEET or picaridin. To verify the effectiveness of insect repellent, go to the EPA’s website: https://www.epa.gov/insect-repellents [links-2.govdelivery.com]
2. Drain: Drain standing water around the house to prevent mosquito breeding.
3. Dawn/Dusk: Mosquitoes are most active during dawn and dusk. Stay inside or take extra precautions to prevent mosquito bites during these times. If doors or windows are left open in the summer, make sure they’re fitted with a screen to keep mosquitos out of the house.
4. Dress: When possible, wear long-sleeved shirts and pants to protect against bites.