No human cases of West Nile virus have been reported in Nevada this year, but if Douglas County does see a case, no one will be able to fault Ron Lynch, manager of the county's mosquito control program.
He's been working to keep the mosquito population at bay for the past two months.
"We've been going pretty strong, doing most of our work on the ground, treating breeding areas," he said. "The larvae hatch out wherever we have stagnant water, like where floodwater has backed up along the river. That can be a real problem."
Lynch has been using more larval than adult control methods, which he attributes to this season's cooler nights.
"I've been doing this for 34 years, and this is one of the strangest years I've seen," he said. "There's a lot of water out there. That's the hard part."
To control larvae, Lynch uses altosid, a chemical that retards their growth so they never emerge from the water.
"There's nothing friendlier than Altosid," Lynch said. "It doesn't harm fish or any other animals. We also use Teknar, a bacillus discovered in Israel that destroys the stomachs of mosquito larvae."
When larval treatments fail, Lynch and his two employees fog residential areas from about 2 to 5 a.m. He said he doesn't know where the mosquitoes will be until residents call.
"We use a chemical derived from chrysanthemums to kill the adults," Lynch said. "There's nothing safer. Roman soldiers used to carry it with them."
The peak season for mosquitoes is July through August, but spraying can continue for about nine months, Lynch said.
"The season could easily go into October if it stays wet," he said.
Mosquitoes harbor the West Nile virus, which they pass on to birds. But only a few birds have been tested for West Nile in Douglas County this year, and none were positive.
Another concern is the mosquito-borne virus that causes St. Louis encephalitis, Lynch said.
Mosquitoes discovered through surveillance at the west end of Wilson Canyon near Yerington harbored the virus, according to Bud Stinson, district manager for the Mason Valley Mosquito Abatement District.
"We trap them every two weeks in the area, and the state does the testing," he said. "Because of enhanced surveillance, we were able to catch it early on, and with an immediate and adequate response, we knocked it out."
There is no vaccination for the disease, which is transmitted to humans by mosquitoes.
Mild infections occur without symptoms, other than fever and headache.
More severe infection is marked by neck stiffness, disorientation, coma, tremors and occasional convulsions, especially in infants.
The mortality rate for encephalitis ranges between 3 and 30 percent. Only three cases were reported in Nevada from 1964 to 1998.
n Susie Vasquez can be reached at email@example.com or 782-5121, ext. 211.
To keep mosquitoes
at bay, health
• Temperatures are ideal for mosquitoes from dusk to dawn. Take extra care to use repellent and protective clothing during evening and early morning.
• Wear long sleeves, long pants and socks when outdoors. Mosquitoes may bite through thin clothing, so spraying clothes with repellent containing permethrin or DEET will give extra protection.
• Limit the number of places around your home for mosquitoes to breed by getting rid of items that hold water. Water should be changed regularly in pet dishes.
• Check, install, or repair screens. Some mosquitoes like to come indoors.
• Report dead birds to Douglas County mosquito control at 782-4642. Dead birds may be a sign that West Nile virus is circulating, but it's also important to remember that birds die from many other causes.
• For updates or more information concerning the West Nile virus in Nevada, access the State Health Division's Web site at health2k.state.nv.us/php/WNVCurrent/WNVactivity.htm.