Umatilla County Reports First Detection of West Nile Virus

The West Umatilla Mosquito Control District will conduct aerial mosquito control spraying this evening. (Photo: Pixabay)

Umatilla County officials report that West Nile virus has been detected in a mosquito sample trapped in Umatilla County.

The mosquitoes were captured on June 21st near the mouth of the Umatilla River in the city of Umatilla. Confirmation testing at the Oregon State University, Oregon Veterinary Diagnostic Laboratory in Corvallis, Oregon took place on June 25. This is the first mosquito detection of West Nile virus in Oregon in 2017.

Residents in the area can expect to see an increase in mosquito control operations based on the positive sample. Ultra Low Volume (ULV) applications of insecticides from truck mounted sprayers will be used to reduce mosquito populations. These applications will typically be made after sunset when mosquitoes are most active. All applicators are licensed by the Oregon Department of Agriculture.

West Nile is primarily a bird disease, and some birds, including magpies, blue jays and crows are especially susceptible. Mosquitoes become infected by feeding on an infected bird and can pass the virus to humans, horses or other hosts when they bite. The public is encouraged to continue to alert district officials when they come across dead birds, so the district can track the spread of the virus. There is a vaccine available to prevent West Nile virus disease in horses, contact your veterinarian for more information.

The risk of West Nile is low but people are encouraged to take appropriate precautions to protect themselves against mosquito bites. Most people who become infected with West Nile Virus do not become ill. Some may develop mild flu-like symptoms such as fever, headache, body aches, and occasionally swollen lymph glands or a rash. In rare cases West Nile may cause encephalitis, or inflammation of the brain. Individuals with severe or unusual headaches should seek medical care as soon as possible. Residents of the district should remain vigilant in protecting themselves from mosquitoes and the diseases that they can carry, such as West Nile virus.

Here are some suggestions to reduce the risk of exposure to West Nile:

· Get rid of old tires and other containers where water can accumulate and serve as a breeding ground for mosquitoes.

· Flush or replace the water in horse troughs weekly.

· Be sure to flush or add mosquito fish to ornamental ponds.

· Avoid outdoor activities at dusk and dawn when mosquitoes are most active.

· Wear long-sleeved shirts and long pants when in mosquito infested areas.

· Use mosquito repellents containing:


· Picaridin

· Oil of lemon eucalyptus

· IR3535 or 2-undecatone. And make sure to follow the directions on the container.

· Screen doors and windows.

· Report mosquito infestations and dead bird sightings to the West Umatilla Mosquito Control District (541) 567-5201

Because horses are also at risk for West Nile, health officials encourage horse owners to check with their veterinarians for vaccination. Veterinarians can arrange for testing of samples from horses suspected of infection with West Nile virus.