Samples gathered around Carson Valley this season have shown no traces of West Nile virus infection said Ron Lynch, Douglas County's Mosquito Control Officer.
"Mosquito pools from Winhaven, Highway 88 near the high school and Hansen Lane (just off Foothill Road) have all tested negative," he said. "That's our latest update."
Lynch said he has received complaints about mosquitoes, but they turned out to be midge flies, a small two-winged fly also known as "no-see-ums" or "punkies." The bugs don't carry the virus, Lynch said.
A magpie from Fallon was the first to test positive in Nevada, weeks earlier than the first positive in 2006, according to a Department of Agriculture press release.
"Last year the first positive bird was also a magpie from Churchill County, found on June 21," the press release said. "One day earlier, a mosquito pool from Lyon County was identified as the first positive specimen of Nevada's 2006 season."
Dr. Anette Rink of Nevada's Animal Disease and Food Safety Laboratory said she would not make any predictions as to the severity of this year's outbreak despite the dry weather.
"The only thing we predict about West Nile is that it's unpredictable. Most predictions by experts are wrong," she said. "I'll be able to tell you later in the year, probably October."
West Nile virus follows a seasonal pattern that begins in late spring, with the peak time for infection occurring in late summer and early fall, usually August and September.
The disease is spread to humans by the bite of an infected mosquito. A record 123 human cases were confirmed in 2006, up dramatically from the previous year when just 30 cases were reported, according to figures from the Nevada Health Division.
Most human infections are mild, causing fever, headache and body aches, often accompanied by a skin rash and swollen lymph glands. If the virus crosses the blood-brain barrier it can cause life-threatening conditions that include inflammation of the brain and spinal cord, according to information from the National Institute of Allergy and Infectious Diseases in Bethesda, Md.
Nevada State Health Officer Dr. Bradford Lee said one person has died due to complications associated with the virus. He urges everyone to use the recommended preventive measures this season.
"I cannot stress enough the importance of everyone, especially people 50 years and older, to use repellent containing DEET and wear long sleeves, pants and socks when outside, especially at dawn and dusk," he said. "Also, remove any standing water from around your house and check to make sure your window screens fit properly."
Most people recover from West Nile virus without treatment. Even those who develop encephalitis or meningitis may only need supportive therapy with intravenous fluids and pain relievers.
Scientists are investigating interferon therapy, a type of immune cell therapy, as a treatment for encephalitis caused by West Nile virus. Some research shows that people who receive interferon may recover better than those who don't receive the drug, but more study is needed, according to information from the Mayo Clinic, which is based in Rochester, Minn.
-- Susie Vasquez can be reached at svasquez@recordcourier.com or 782-5121, ext. 211.
