The Yakima Health District (YHD) is investigating a probable case of West Nile virus in the Lower Yakima Valley. The probable case, a female in her fifties, was first brought to the attention of health officials after preliminary testing performed at a commercial laboratory revealed elevated levels of antibodies to West Nile virus.
The individual also reported a history of mosquito bites along with symptoms such as fever, headaches, muscle aches, sore throat and a rash that started in mid-August. These symptoms are consistent with the mild form of infection known as "West Nile virus fever."
The individual reports no recent travel outside of the county and is currently recovering.
Although additional tests run at the Washington State Department of Health's Public Health Laboratory have also come back positive, tests performed by the Centers for Disease Control and Prevention must also show positive results before the individual can be confirmed as a West Nile virus case. The Center for Disease Control results are expected sometime in early October. In the interim, it remains safe and wise to assume that West Nile virus is present in the community and is being transmitted to humans.
Although the virus has been detected in Yakima County horses, birds and/or mosquitoes over the past four consecutive summers, this would still be the first human case of West Nile virus proven to have been acquired in Yakima County.
Only one in five infected people develop symptoms of West Nile virus. The onset of illness occurs three to 14 days after being infected by the bite of a mosquito carrying the virus. Illness typically resolves without medical intervention. Symptoms include varying degrees of fever, headache, body aches, rash and swollen lymph nodes. A more serious form of the virus affects less than 1 percent of symptomatic cases, producing symptoms such as neck stiffness, disorientation, coma, tremors, convulsions, muscle weakness, paralysis or even death.
Individuals over 50 years of age appear to be more susceptible to developing this more serious form of the virus.
People experiencing any of the above symptoms should consult their medical provider.
"The possibility for human cases of West Nile virus has been a reality since the virus was first detected in our county several years ago" says Laura Charters, environmental health specialist with the Yakima Health District.
"We don't want residents to be overly alarmed by this news," she added. "Instead, our hope is that by knowing there is a possible case in our county, residents will become even more diligent about reducing breeding grounds by eliminating standing water, avoiding mosquito infested areas and using mosquito repellent when necessary.