Steamboat Springs West Nile virus was found in Routt County for the first time Tuesday when a bird tested positive for the virus.
The infected raven was found on Village Drive near Mount Werner and was submitted for testing Monday, Routt County Environmental Health Director Michael Zopf said. The positive test came back Tuesday.
Although there have been cases of infected animals near Routt County, including a horse in Moffat County that tested positive for the virus last summer, this finding marks the first sign of the disease in Routt County.
With more than 490 documented human cases across the state, officials have said they are not surprised that the virus has made it into Routt County.
"It's not unexpected to see a positive bird in Routt County," said Tim O'Brien, regional epidemiologist for Northwest Colorado.
No human cases have been reported in Routt County, said Sue Birch, director of the Northwest Colorado Visiting Nurse Association. One tourist was diagnosed with the virus while in Routt County, but from interviews officials concluded the visitor had contracted the disease while on the Front Range.
The closest human cases to this area are in Summit and Delta counties, which have had one case each this summer.
Because the virus has been found in the county and because there are four to six weeks left in mosquito season, people should be careful to prevent bites, Zopf said.
"If birds are positive for it here, that means that the virus can be transmitted to horses, humans and other animals," Zopf said.
"(But) it's entirely preventable. If you don't get bitten by a mosquito, you're not going to get it."
To prevent bites, officials are urging people to wear insect repellant containing DEET whenever they are outdoors and to limit outdoor activity at dawn and dusk, when mosquitoes feed. Elderly people, children, or people with health problems should be especially careful.
Officials also are recommend that people drain standing water on their property and be sure their window screens are in good condition.
The virus first appeared on the East Coast in 1999 and has been moving steadily westward, O'Brien said. The virus was found for the first time in Colorado last summer.
The recent outbreak in the state is not unusual, and the second summer the virus is in an area is usually the worst, O'Brien said. That's because the mosquitoes that carry the virus from one animal to another have a chance to grow in number.
Because the virus had never been seen before in North America, people, mosquitoes, horses and birds have not had a chance to build an immunity to it, he said.
"By the second summer, away we go," O'Brien said.
Fortunately, the third summer usually sees a diminished infection rate because the birds that were infected have died and the birds that have natural immunity are still around, he said.
Colorado's mountain areas have had fewer incidences of the virus because of one key factor: The cooler weather means mosquitoes have a longer breeding cycle and can't build big populations as quickly as they can in areas along the Front Range or Eastern Plains.
"It's not that it's not going to happen in the mountains, but we expect it to take longer to get to the mountains and the effects should be diminished," O'Brien said.
Also in the mountains, winter may come earlier, killing the mosquitoes more quickly.
The mosquitoes have another foe: Efforts by officials to kill them before they develop. Mike Neumann, the city's open space supervisor, said the city has put out a mosquito-killing larvacide three times this summer.
Still, the message that officials are sending to residents is clear: Mosquitoes are here, and people should take precautions to avoid bites.
"There is no cure for West Nile Virus," O'Brien said. "Once you get it, you may be lucky and have no symptoms, or you may be unlucky and get a severe disease and, rarely, die. ... The only way to deal with it is prevention."
For more information, visit www.fightthebitecolorado.com or call 1-877-462-2911.