Health officials on Thursday confirmed a Benton County woman was hospitalized with West Nile virus.
The woman, in her 50s, is the third confirmed case of West Nile in Washington this year, and the second person to be infected without traveling out of state.
A fourth case has been confirmed in Clark County, where a teenage boy was infected while traveling outside of Washington.
The first and second case were a Pierce County woman in her 70s who likely was exposed while traveling, and a Yakima County man in his 30s who hadn't left the state, the state Department of Health said.
The federal Centers for Disease Control reports more than 2,600 cases of West Nile infection in 48 states through Tuesday -- the highest number since the virus first was detected in the United States in 1999.
The public health agency reported that 118 people have died from the virus nationwide this year.
About 40 percent of this year's West Nile infections have been reported in Texas, with many of the rest coming from South Dakota, Mississippi, Oklahoma, Louisiana and Michigan.
Washington's first human West Nile infection was reported in 2006, with 2009 the peak year so far for the illness when there were 38 human cases reported in 16 counties, and one death -- a 71-year-old Sunnyside woman.
Only two human cases were reported statewide in 2010 and none last year.
Most of this year's West Nile activity has been centered in Yakima County, where health officials have found four of the five virus-positive mosquito samples collected since the season started. The fifth was found in Franklin County.
A horse near Grandview was euthanized in late August after it was confirmed the 2-year-old gelding had West Nile. While initially reported in Yakima County, local health officials said Thursday that the equine case since has been attributed to Benton County.
And a mosquito sample from north Franklin County that was reported to have tested positive for the virus was deemed not to contain the virus in follow-up testing.
West Nile virus is transmitted from mosquitoes to birds, horses and people.
Only about one in 150 people infected becomes seriously ill, but health officials recommend using bug repellent and wearing long pants and sleeves outdoors when mosquitoes are active to avoid bites. Also check for standing water around your home.
Horses can be vaccinated against the virus, but no human vaccine exists.
In humans, West Nile can cause inflammation of the brain and lining of the spinal cord. Symptoms may include fever, headache, body aches, neck stiffness, stupor, disorientation, tremors, convulsions, muscle weakness, paralysis and coma.
People with severe symptoms should contact a doctor, health officials advised.
-- Michelle Dupler: 582-1543; firstname.lastname@example.org