08/31/2026
PUBLIC HEALTH WARNING
Probable Human Case of West Nile Virus Reported in Sheridan County
Sheridan County Montana Public Health Department is notifying residents of a probable human case of
West Nile virus (WNV) in Sheridan County.
About West Nile Virus
West Nile virus is a mosquito-borne disease that can cause illness in people. The virus is primarily spread
through the bite of an infected mosquito. While many people infected with West Nile virus do not develop
symptoms, some may develop fever, headache, body aches, vomiting, rash, or swollen lymph glands.
In rare cases, West Nile virus can cause serious illness affecting the brain and spinal cord. Older adults and
individuals with certain medical conditions may be at greater risk for severe disease.
Protect Yourself and Your Family
• Use an EPA-registered insect repellent containing DEET, picaridin, IR3535, oil of lemon eucalyptus
(OLE), or 2-undecanone when outdoors.
• Wear long sleeves and long pants when mosquitoes are active.
• Avoid outdoor activities around dawn and dusk, when some mosquitoes are most active.
• Keep doors and windows closed or use screens to prevent mosquitoes from entering homes.
• Remove standing water around your property where mosquitoes can breed. Empty and clean birdbaths,
buckets, flowerpots, tires, and other containers that hold water.
• Maintain swimming pools and other water features according to recommended maintenance practices.
When to Seek Medical Care
Most people who become infected with West Nile virus have no symptoms or experience only mild illness. If
you develop symptoms such as fever, severe headache, confusion, muscle weakness, tremors, or other
neurological symptoms, contact your healthcare provider promptly.
There is no specific medication to treat West Nile virus. Treatment focuses on relieving symptoms and
supporting recovery.
The Sheridan County Montana Public Health Department encourages everyone to take precautions against
mosquito bites throughout mosquito season.
Questions? Contact Sheridan County Montana Public Health Department • 406-765-3410