West Nile Virus: Still a risk in Sierra Nevada
August 22, 2007
The summer’s end is around the corner, but that’s not to say Tahoe-Truckee residents are safe from mosquito bites and their associated viruses.
“The peak of West Nile virus transmission is mid-July to mid-September,” said Vector Ecologist Jamesina Scott with Placer Mosquito and Vector Control. “We are smack in the middle of the highest risk time.”
Due in part to a dry winter, Placer and Nevada county authorities have received reports of few dead birds or West Nile-positive mosquito samples. All the virus activity has been in the western parts of both counties, but Tahoe-Truckee is not necessarily in the clear.
“Regardless of where they were picked up … if it’s in the county it means it’s possible to get West Nile virus,” said Peggy Zarriello, Nevada County environmental specialist.
So far this year, 108 human cases of the mosquito-borne disease have been reported in California, but none in Placer, Nevada or El Dorado counties.
“The virus is here so I can’t say there’s no risk. People need to take some common sense precautions,” Scott said.
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West Nile was first detected in the United States in 1999 and in Northern California less than four years ago. The disease has been classified as a seasonal epidemic known to cause serious illness that can lead to an infection of the brain, called encephalitis.
In 2006, 278 human cases of the West Nile Virus were reported in California including one from Nevada County and eight reports from Placer County. None of the local cases was fatal, according to the California West Nile virus Web site.
“Although we have not detected any West Nile virus around Lake Tahoe this year, in previous years West Nile virus has been found on all sides of the lake in birds, mosquitoes and humans,” Scott said in an exchange of e-mails.
California is experiencing increasing West Nile activity, Scott said, and the state government has stepped up to fight the spread of the disease.
“The governor authorized a total of nearly $10 million, I think, for enhanced West Nile control and surveillance,” she said.
Gov. Arnold Schwarzenegger last week approved nearly $30,000 for Placer mosquito control and surveillance, according to the California West Nile virus Web site.
The Placer Mosquito and Vector Control District ” a special district separate from the county ” provides a full-time technician serving the communities around Lake Tahoe.
The district regularly surveys mosquitoes and mosquito-born diseases, which includes maintaining a flock of sentinel chickens in the Tahoe Basin that are sampled every two weeks for antibodies to the West Nile, among other viruses.
“Our goal is to reduce the number of mosquitoes that emerge as adults. We want to get them before they fly,” said Scott.