Early samples show no signs of West Nile
Ed Fleming and Kevin Wheeler are knee deep in buggy territory.The biologists, who work for OtterTail Environmental, are in a grassy field near B&B Excavating in Edwards, where trees grow tall, the ground stays cool and a grazing pasture is just a few steps away.This is prime mosquito breeding land.The duo have spent the past two weeks collecting and testing the local mosquito population for West Nile virus, which was responsible for more than 60 deaths in Colorado last year, according to the Centers for Disease Control. The results so far are encouraging: Field samples show there are, indeed, mosquitoes in Eagle County that are known to carry the West Nile Virus. But none of those mosquitoes, known as the culex species, have tested positive for the virus.Still, county officials warn against complacency.”I think the thing to say is we’re finding the type of mosquito that carries the virus in low numbers, but we are still finding them,” said Ray Merry, the county’s director of environmental health. “The only sure-fire way to protect against West Nile is to not get bit.”
Like many counties across the state, Eagle County is testing the local mosquito population to determine the risk of contracting West Nile virus.OtterTail has set up six collection traps across the county, all are west of Vail. culex mosquitoes rarely live in elevations above 8,000 feet. Of the 46 mosquitoes trapped and tested so far, only four were culex mosquitoes and none tested positive for West Nile.Two of the culex species were found in El Jebel; the other two were found in Eagle. “That’s not to say there aren’t more,” Fleming said. “We can find culex mosquitoes up to 10,000 feet.” The trap used in Edwards attracts female mosquitoes that have just eaten and are ready to lay eggs. Biologists cannot test the larvae, but they can test the adult mosquitoes to determine if they have contracted the virus while feeding. West Nile usually is passed from birds to mosquitoes. Rather than spraying insecticides indiscriminately to kill all mosquitoes, OtterTail’s biologists are targeting their efforts specifically on the culex mosquito.”It’s more environmentally friendly because you aren’t killing off mosquitoes that eat bugs,” Fleming said. “It reduces costs because there is not as much labor involved. And you aren’t paying for the extra material for the actual treatment.”While some communities in the valley have opted to spray for all mosquitoes, it’s really more to avoid the public nuisance than a health issue, Merry said. “We wanted to arrive at the proper balance between public health protection and environmental protection,” he said. “We felt it was very responsible to focus on culex mosquitoes. There’s no need to do any abatement if we didn’t find them.”Fleming and Wheeler apply a bacteria to watery areas to kill off culex mosquitoes. When ingested, the bacteria, BTI, ruptures the gut of this type of mosquito. Fleming said the treatment doesn’t affect humans or animals, and most bugs aren’t affected by the bacteria, either. OtterTail will continue to test mosquitoes every week until mid-September.
While Eagle County has dodged West Nile virus so far, Wheeler and Fleming don’t want residents and tourists to stop wearing insect repellent. They can’t test every mosquito in the county, and they are still early in the testing period. So far this year, there have been 18 confirmed cases of West Nile in Colorado. Just this week, Mesa County reported a human case of the virus. An Edwards woman contracted the virus last year, though it’s difficult to determine where she was when she was bitten by the infected mosquito. An Eagle County horse contracted and died from the virus last year. The public shouldn’t let their guard down, Merry said. West Nile virus is in Colorado, and traveling to other parts of the state could put local residents at a risk for the illness.”It’s important to have repellent with you, in a glove box, so you aren’t caught off-guard when you are out for a walk,” he said. It seems like people are getting the message. In his rounds throughout the county, Wheeler said he gets the chance to talk to local residents, particularly private property owners who have a trap on their land or live near a trap. “Most people are extremely curious,” he said. “They want to know what they can do.”Some assume because they don’t have a pond or a creek near their property, mosquitoes aren’t likely to hover near their homes. But Fleming said all it takes is coffee can full of water, or even a tire thrown in the yard that collects water, to create a prime breeding ground for mosquitoes.Land used for grazing or irrigated fields also provide plenty of nutrients for mosquitoes larvae to thrive, Merry said. “I think we’ve gotten people’s attention,” he said. “We’ve put on a huge public outreach program, and we’re still able to talk to special groups and homeowner’s associations.”I’ve been very happy with the community’s response.”
============================================================Location of mosquito traps in Eagle County:• Two in El Jebel• One in Gypsum• One in Eagle• One in Edwards• One in Eagle-VailNumber of mosquitos tested so far (two weeks of sampling): 46Number of culex mosquitos, the species known to carry West Nile: 4========================================================