Alameda County’s first West Nile Virus victim has survived her encounter with the deadly disease—contracted not here but in Colorado—say local public officials who remain deeply concerned about the virus’s spread into California.
The 47 year-old woman, whose name and city have not been disclosed, was released from the hospital Friday in good health, according to Alameda County Public Health Department spokesperson Sherri Willis. She was the first Californian infected this year.
Public health officials say they are almost certain she acquired the virus last month during a hiking trip in Colorado—a hot spot for the disease this year.
There is not yet any evidence of infected mosquitoes, which carry the disease, in California. But officials say the virus could reach the state in a matter of weeks.
West Nile first appeared in New York in 1999, and has moved about a quarter of the way across the country each summer, when the virus peaks.
“We expect to see it in California this year—this month or next,” said Ken August of the California Department of Health Services.
Dr. Vicki Alexander, Berkeley’s director of maternal, child and adolescent health, said the Alameda County victim is not a Berkeley resident, to her knowledge, and that city officials have not changed their readiness level.
“Everybody’s on alert, no matter what,” she said.
Bruce Kirkpatrick, entomologist with the Alameda County Mosquito Abatement District, said his agency set up 11 mosquito traps around the woman’s condominium to make sure that she wasn’t infected locally. Kirkpatrick shipped off captured mosquitoes to UC Davis’ Arbovirus Research Unit Monday for testing. He expects results in about a week.
“We don’t anticipate anything positive,” he said. “I would guess [the odds are] a million to one. We just want to make sure she didn’t get the virus in California.”
Last week, the victim was suffering from acute flaccid paralysis, a rare neurological syndrome which has created severe weakness in her legs, according to the state health department.
The woman reported getting bitten by mosquitoes while traveling in northeast Colorado in late July. She returned to the state July 26, exhibited the first symptoms of the disease July 30 and was hospitalized Aug. 7. But health officials said they did not have enough proof to announce the case until last week.
Colorado has become the heart of West Nile country, with 247 human cases and six deaths reported as of Monday, according to the U.S. Centers for Disease Control and Prevention, making it the heaviest hit state this year by far. South Dakota was second with 66 cases and no deaths as of Monday.
Nationwide, there have been 470 reported human cases and 10 deaths this year. Last year, there were 4,156 reported cases and 284 deaths across the country.
The only California case last year involved a Los Angeles County woman who recovered from the virus. Health officials believe she was infected by a mosquito that arrived in the state by way of car or airplane, since they found no evidence of infected California mosquitoes.
West Nile is a “flavivirus” commonly found in Africa, West Asia and the Middle East and is closely related to the St. Louis encephalitis virus found in the United States.
Mosquitoes spread the disease by biting an infected animal—usually a bird or a horse—and passing the virus to a human or another animal.
August, of the state health department, said mosquitoes cannot pick up the disease by biting an infected person because humans develop antibodies to the virus once infected. The Alameda County woman infected in July and all other human victims, he said, pose no threat to the public health.
Most people infected with West Nile Virus have no symptoms, but about 20 percent develop a fever, headache or body aches. About one in 150 come down with more severe symptoms, including encephalitis, a life-threatening swelling of the brain.
Public health officials recommend that residents eliminate standing pools of water, where mosquitoes breed, from their property. They also suggest wearing long sleeves and using insect repellent.