West Nile virus, a mild flu-like disease spread by mosquitoes, has been detected in mosquitoes at a testing site in Umatilla County, according to Oregon Public Health officials.
The mosquitoes, found in Umatilla, are the first to test positive for the disease in Oregon in 2019. The mosquitoes were collected last week by the West Umatilla Mosquito Control District and confirmation testing took place on Monday at the Oregon State University Veterinary Diagnostic Laboratory in Corvallis.
(West Nile Virus Detected in Morrow County)
Health officials are advising people in Umatilla County to take precautions against mosquitoes to avoid the risk of infection, including preventing mosquito bites. West Nile is spread to humans through the bite of an infected mosquito.
About one in five infected people may show signs of West Nile virus. People at risk of serious illness include individuals 50 and older, and people with immune-compromising conditions, such as diabetes and high blood pressure.
West Nile symptoms may include fever above 100 degrees and severe headache, stiff neck, mental confusion, muscle weakness, shaking, paralysis or rash. People should contact their health care provider if experiencing any of these symptoms.
The incubation period is usually two to 14 days. Rarely, infected individuals may develop an infection of the brain or spinal column that can be severe or may cause death. This is especially of concern to those who have a compromised immune system, or the elderly.
The number of mosquito pools – samples of about 50 mosquitoes – testing positive in any area could lead to infection. Dr. Emilio DeBess, veterinarian at the Oregon Health Authority’s Public Health Division, recommends people and animals be protected against mosquito bites.
“It’s very easy for people to prevent bites from mosquitoes that may carry West Nile virus,” DeBess says. “Although the risk of contracting West Nile virus is low, people can take simple precautions to keep these insects at bay if they’re headed outdoors.”
DeBess offers these tips:
- Eliminate sources of standing water that are a breeding ground for mosquitoes. This includes watering troughs, bird baths, clogged gutters and old tires.
- When engaged in outdoor activities at dusk and dawn when mosquitoes are most active, protect yourself by using mosquito repellants containing DEET, oil of lemon eucalyptus or Picardin, and follow the directions on the container.
- Wear long-sleeved shirts and long pants in mosquito-infested areas.
- Make sure screen doors and windows are in good repair and fit tightly.
In Oregon during the 2018 mosquito season, there were two human cases of West Nile virus in Harney and Clackamas counties. The virus was found in one bird, 58 mosquito pools — samples of about 50 mosquitoes each — and two horses. In 2017, seven humans, 92 mosquito pools, five horses and one bird tested positive for West Nile. The virus also can be found in chickens, squirrels and dogs.
Climate change effects such as increased temperature and changes in rainfall have led to longer mosquito seasons and are contributing to the spread of West Nile virus, health officials say. They agree these, and other climate change indicators must be considered to help people better prepare for future transmission of the disease.
Additional information about West Nile virus is available at the Oregon Health Authority website.
