KENNEWICK — The first mosquitoes discovered to be infected with West Nile virus this year in Washington state were just across the Benton County line a few miles west of Prosser.
The Yakima Health District said the mosquitoes were collected from the Sunnyside unit of the Sunnyside-Snake River Wildlife Area in Yakima County.
So far this year there have been no people or animals, such as horses, reported infected with the mosquito-borne virus, which usually is primarily a problem in Washington east of the Cascade Mountains.
Last year 85 samples of mosquitoes collected in the state were positive for West Nile virus, all in the Eastern Washington counties of Benton, Grant and Yakima.
The Washington state Department of Health reported that one person in Walla Walla County was sickened with the West Nile virus last year and a Franklin County woman was ill with a rare case of St. Louis encephalitis, a disease transmitted by infected mosquitoes.
In addition three mammals — at least two of them horses — in Benton and Walla Walla counties had the virus last year.
The last death of a person reported from the virus in the Tri-Cities was a woman in her 70s in 2016.
Most people and animals bitten by mosquitoes infected with West Nile virus develop no symptoms.
About 1 in 5 people who are infected will develop fever with other symptoms such as headache, body aches, joint pains, vomiting, diarrhea or rash.
Most people recover completely, but fatigue and weakness can last for weeks or months.
Serious illness occurs in fewer than 1 in 100 people infected with West Nile virus. The risk of severe infection is highest among people 60 or older and people with certain medical conditions such as cancer, diabetes, hypertension and kidney disease.
There is no vaccination against the virus for people, but horses can be vaccinated.
Preventing West Nile virus infection
The best way for people to prevent the disease is to take steps to lessen the chance of a mosquito bite until the first hard frost of the year.
The Benton Franklin Health District recommends:
- Drain sources of standing water around your home each week so mosquitoes do not hatch.
The mosquitoes most likely to spread West Nile virus prefer to breed in water found in containers, tires, buckets and other small sources of stagnant water. One female mosquito can lay 250 eggs in a batch that can turn into 250 adults within a week.
