Jul 18, 2013 - By Eric Blom, Staff WriterFremont County Weed and Pest has found mosquitoes carrying West Nile virus on Snavely Lane between Hudson and Lander.
Weed and Pest assistant supervisor Nancy Pieropan said she was not aware of any cases in humans or horses, which also can contract the virus.
"I didn't find any near Riverton, but West Nile is in the area," Pieropan said. "I think people need to behave like West Nile's in the area."
Fremont County Weed and Pest supervisor Lars Baker said he spoke with Riverton public services director Bill Urbigkit, who said he does not expect the city to change its mosquito spraying program because West Nile has not been discovered in Riverton.
"We constantly re-evaluate the program to do the best we can," Baker said. "If West Nile becomes an issue we'll probably increase foggings per week."
He said the city's program kills about 98 percent of mosquitoes in the city, but it is less effective in more rural areas.
Pieropan said the mosquitoes she trapped Wednesday registered a clear positive for West Nile. Wyoming considers a score of 50 on a test to be positive for the virus., she said.
The mosquitoes she tested registered higher than 650, the highest the county's testing machine goes.
"There were some mosquitoes in there with West Nile," Pieropan said. "You're going to find it in the mosquitoes before it comes up in the human or horse population."
To test mosquitoes, Pieropan sets out traps in many locations around the county. She then pulls out the Culex tarsalis mosquitoes --the only species in Wyoming that is a West Nile vector -- and prepares them on slides. After allowing the slides to cure, she inserts them in the machines, and it quickly returns a reading.
The location where the mosquitoes were trapped is within flying distance of Lander and Hudson, Pieropan said. That and the fact that the county program can only trap a small number of mosquitoes are reasons for caution, she said.
People can take several precautions to avoid contracting the virus, Pieropan said.
Dressing in long sleeves and long pants can help prevent people from being bitten. Mosquitoes feed most actively at dusk and dawn, so people should avoid being outside at those times.
Residents also can drain standing water around their homes, such as bird baths or decorative ponds. Other options are to keep water flowing or treat it so mosquito larva cannot grow.
Lastly, Pieropan advises using an effective insect repellant containing DEET.
Pieropan recommended visiting www.badskeeter.org for more information about West Nile virus.
In human, the virus often goes unnoticed, but it can cause flu-like symptoms and, in severe cases, encephalitis and even death.
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