Mosquito-Borne Diseases

Learn about mosquito-borne illnesses, how they spread, and how to reduce your risk in Flathead County.

When to Seek Medical Advice

Contact a healthcare provider if you develop symptoms such as fever, severe headache, body aches, confusion, stiff neck, weakness, or other concerning symptoms after mosquito bites.

Call 911 or seek emergency care for severe symptoms, including confusion, seizures, trouble speaking, trouble walking, or signs of serious illness.

Diseases Associated with Mosquitoes

West Nile Virus

West Nile virus is the primary mosquito-borne disease concern in Montana. Most people infected experience mild or no symptoms, but severe illness can occur in rare cases.

Jamestown Canyon Virus

Jamestown Canyon virus is a rare mosquito-borne illness identified in parts of the northern United States and Canada. Most infections are mild, though severe neurological illness can occur in uncommon cases.

Travel-Related Mosquito Illnesses

Diseases such as Zika, dengue, chikungunya, and malaria are generally associated with travel outside Montana. Travelers should follow mosquito bite prevention guidance when visiting areas where these illnesses occur.

How Mosquito-Borne Diseases Spread

A mosquito bites an infected bird or animal. Some viruses, including West Nile virus, are maintained in nature through birds and mosquitoes.
The mosquito becomes infected. After feeding, the mosquito may carry the virus.
The mosquito bites a person or animal. An infected mosquito can spread the virus through a bite.

Who Has a Higher Risk of Severe Illness?

Anyone can be bitten by mosquitoes, but some people may have a higher risk of severe illness from mosquito-borne infections.

Adults age 60 and older
People with weakened immune systems
People with certain chronic health conditions
People who spend a lot of time outdoors during mosquito season

Reduce Your Risk

Prevent Mosquito Bites

Use EPA-registered insect repellent.
Wear long sleeves and pants when mosquitoes are active.
Consider treating clothing and gear with permethrin.
Use extra caution at dawn and dusk.

Reduce Mosquito Habitat

Dump standing water from buckets, tires, toys, and containers.
Clean gutters and drainage areas.
Change water in bird baths, pet bowls, and stock tanks regularly.
Cover or store items that collect rainwater.

Protect Your Home

Repair window and door screens.
Use air conditioning when possible.
Keep doors closed when mosquitoes are active.
Report problem standing water when it cannot be removed.

How Flathead County Helps

Flathead County Mosquito Control uses monitoring, habitat reduction, larval control, and targeted treatment when needed. The program focuses on reducing mosquito populations while using control methods carefully and responsibly.

Residents can help by removing standing water around their homes and reporting areas where standing water may be producing mosquitoes.

Return to Mosquito Control Program