County biting back at West Nile virus |

County biting back at West Nile virus

Jeremy Heiman
Special to the Post Independent

The Garfield County Commissioners agreed Monday to sign a $100,000 contract with Colorado Mosquito Control Inc. of Broomfield to reduce the threat of West Nile virus during the coming warm months.

West Nile virus, which is carried by mosquitoes, infected 2,945 Colorado residents last year, and killed 55 in the state.

Garfield County vegetation management director Steve Anthony said the county government will fund the entire cost of the program. But town governments in the county have agreed to pay the county for $30,000 for mosquito control near their towns.

The company’s mosquito control program will cover 50 square miles of the county, concentrating on towns and other heavily populated areas.

Carbondale, Glenwood Springs, New Castle, Silt, Rifle and Parachute cover about 16 square miles total, Anthony said. The remaining 34 square miles of coverage will be concentrated in populated rural areas.

“What we’re really looking for is where population densities overlap with potential mosquito habitat,” Anthony said. “But we’re not just going to blanket spray 50 square miles.”

Project starts with mapping

Colorado Mosquito Control will start the project by mapping the areas that most urgently need mosquito control, working with the county’s mapping office.

“We have to steer them and help decide which 50 square miles to treat,” Anthony said.

The company will monitor the presence of West Nile-carrying mosquitoes by setting up traps in towns and likely mosquito habitat areas. The contents of the traps will be examined for mosquitoes of the species culex tarsalis, the primary West Nile carrier found in this area.

Mosquito control work will concentrate on areas where heavy concentrations of culex mosquitoes are trapped, but also based on the company’s field reports and on complaints, Anthony said.

Bird deaths due to West Nile virus and human cases of the disease will bring heavier mosquito control efforts as well.

Dead birds will be tested and test swabs sent to the Colorado Department of Public Health and Environment.

Anthony said the county wants to know about dead birds, but he emphasized that only crows, ravens, magpies and jays are subject to West Nile virus infection. Dead birds of any other species do not indicate the presence of the disease.

Second year brings huge increase in cases

Last year, about 10 infected birds were found in Garfield County. About 10 horses also became infected with West Nile virus in the county, and two human cases were reported.

Anthony said the progression of West Nile virus in an area is usually characterized by a few cases in the first year, then a huge increase in cases the second year, with numbers tapering off after that.

This progression was seen on Colorado’s Front Range, which saw a handful of cases in 2002 and thousands in 2003.

For Colorado’s Western Slope, 2004 will be the second year.

Though human population is lower and flood irrigation (which provides stagnant water for mosquito breeding) isn’t as prevalent in western Colorado, it may be in for a big year if residents don’t take some measures themselves, Anthony said.

The county is trying to educate people about preventing West Nile virus.

Anthony said his office did about 20 presentations to various groups last season, reaching about 500 people.

These efforts will increase this year, assisted by a citizen task force from across the county. Members of that group are available to speak to civic groups and service organizations, emphasizing methods for preventing the disease.

How to protect against West Nile

The two important means of prevention, Anthony said, are eliminating standing water where mosquitoes breed, and protecting against mosquito bites.

A two-pound coffee can accidentally left to fill with rainwater can breed 10,000 mosquitoes over the course of a summer, he said, and old tires are the leading habitat of mosquito larvae.

Rain gutters dammed up with leaves can collect water and provide breeding habitat, and the water in bird baths should be changed every three to four days. Stock tanks should also be changed frequently.

Preventing insect bites is also an essential step in prevention of West Nile virus, Anthony said.

A survey of West Nile victims last year revealed that only 12 percent regularly wore an insect repellent containing the ingredient known as DEET, the most effective known repellent.

For adults, Anthony said, the product should contain 10 percent to 35 percent DEET; for children, 10 percent or less.

A soy-based organic insect repellent, Bite Blocker, is available for those who don’t want to wear DEET, Anthony said, and a cosmetic product called Avon Skin So Soft also is reputed to have repellent characteristics.

More information on the prevention of West Nile virus is available on a state of Colorado Web site,

Contact Jeremy Heiman: 945-8515, ext. 534

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