West Nile Virus Confirmed in Mosquito Samples in Three Montana Counties

Take steps to avoid mosquito bites, state health officials say State and local public health officials are reporting the season’s first West Nile Virus (WNV) detections with three counties confirming positive mosquito samples.

Cascade, Sheridan and Yellowstone counties have all had a positive mosquito sample for WNV. To date, no cases of WNV have been identified in a human but the detection of WNV in Montana is a reminder of the importance of avoiding mosquito bites. Most people who become infected with WNV experience no symptoms, but 1 in 5 develop a mild illness, with symptoms such as headache, body aches, joint pains, vomiting, diarrhea or a rash. Other individuals, fewer than 1 out of 150, may become severely ill with encephalitis or meningitis (inflammation of the brain or surrounding tissues). Most people recover completely, but fatigue and weakness can last for weeks or even months.

DPHHS Communicable Disease Epidemiologist, Erika Baldry states, “Late July and early August is when we typically see WNV activity pick up here in Montana. Our season can begin as early as July and because it can take some time to become ill,

West Nile Virus Confirmed in Mosquito Samples in Three Montana Counties we can receive reports of ill individuals as late as October.”

There is no available treatment for WNV infection other than supportive care. Individuals who develop any of these symptoms should see their healthcare provider. Detection of WNV in mosquito samples is a good indication that WNV is in Montana. WNV is a vector-borne disease meaning that for individuals to become infected, they must be bitten by an infected mosquito.

DPHHS reminds Montanans to take precautions and protect against WNV by following the 4 D’s of prevention.

The 4 D’s of West Nile Virus prevention:

1. DEET: Use insect repellent such as DEET or picaridin

2. Drain: Drain standing water around your house to prevent mosquito breeding

3. Dawn/Dusk: Mosquitoes are most active during dawn and dusk. Stay inside or take precautions to prevent mosquito bites during these times

4. Dress: When possible, wear long sleeved shirts and pants to protect yourself from bites

For more information about WNV protection, contact your local health department or visit the state health department website at: http://dphhs.mt.gov/