West Nile Virus was detected in 2,947 people in Colorado last year -- by far more cases than in any other state.
No one knows for sure how the virus will affect the Western Slope this year, but Routt County municipalities and agencies are working together to monitor mosquitoes and slow the spread of the virus through mosquito control and public education.
"We will see the virus again," said John Pape, an epidemiologist with the Colorado State Department of Health and Environment. "It's hard to say at what level, but I don't think it will be worse than last year."
After decades in Africa, Asia and the Middle East, West Nile Virus was first documented in North America in 1999 in New York and has been spreading steadily westward since. It is an avian disease that is transmitted to other animals through mosquitoes.
Many people who are bitten by an infected mosquito do not get sick, but 54 people in Colorado died last year, and 622 developed neurological problems.
No human cases have been reported in Routt County by the state, but a Hayden man tested positive last year using a type of blood test not recognized by the state.
Most of Colorado's 2003 cases were reported on the Front Range.
A longtime former Steamboat Springs resident, Peggy Grosjean, was living in Boulder last year when she was bitten and infected. She lay unconscious for about
three days after developing encephalitis.
Grosjean was not ignorant of West Nile Virus. She wore bug spray daily, but forgot on one occasion while jogging.
"It was a gorgeous sunset, so I kept going," she said.
When the symptoms came, Grosjean checked herself into Boulder Community Hospital. Though she often volunteered there, she was unaware of where she was by the time she arrived at the front desk, said Dr. Nelson Gantz, an epidemiologist at the hospital.
"She wasn't making any sense," Gantz said. "We got her into the intensive care unit immediately."
Encephalitis had caused her brain to swell. Doctors told her family she might not make it through the night.
"I was too sick to be scared," Grosjean recalled about waking from her coma-like state. "I was so sick, I thought, 'Do I really want to live?' I knew it was bad when I saw my whole family gathered around me."
Doctors told Grosjean she developed encephalitis because her immune system already was weakened from taking medication for rheumatoid arthritis.
But it is not only the weakened, young and old who are susceptible to West Nile Virus. It can affect anyone at any age in any health condition, said Mike Zopf, director of the Routt County Department of Environmental Health.
"Young people should not be fooled into thinking they are at less of a risk," Zopf said.
The median age for reported cases of West Nile Virus last year was 47.
Because the virus can affect anyone, officials across the country are encouraging people to wear insect repellent with DEET.
"The front line in preventing infection is personal protection," Pape said.
Officials also are preparing traps and other mosquito-control techniques. They emphasize reducing standing water, which is the habitat for mosquito larvae. Finding and reducing standing water can be a significant way to reduce the mosquito population, Zopf said.
"The destruction of a single mosquito larva in May eliminates the need to kill thousands of adult mosquitoes in August," states a report from Routt County Environmental Health and the Colorado State University Cooperative Extension Service.
Routt County is using traps and samples from individual standing water bodies to determine where mosquitoes are concentrated. When a concentration is found, larvae are killed with the larvicide Bacillus thuringiensis israelensis, or Bti.
Bti is "one of the safest products that's ever been come up with" because it only affects mosquitoes, which have alkaline-based digestive systems, said Scott Schell, an entomologist at the University of Wyoming.
"We're all in favor of larvicide because it stops the problem before it starts," said Nadine Harrach of the Routt County Environmental Health Department. "If you're only spraying for adult mosquitoes, you almost need someone on the ground spraying 24 hours a day."
Officials also recommend giving horses vaccines for West Nile Virus.
A vaccine is not available for humans, yet. Three private companies are researching possible vaccines, Pape said, but human vaccines always take longer to develop because of health and legal risks.
Horses also are more likely to develop symptoms if infected with the virus, Schell said.
There are more than 3,000 species of mosquitoes, but only one has been found to be a vector of West Nile Virus -- Culex tarsalis.
The species thrives in irrigated agricultural lands, which is why West Nile Virus was so prevalent in the Midwestern and Rocky Mountain regions last year, Schell said.
Though Colorado had the most reported cases, Wyoming and South Dakota were hit hard, too, Pape said. They have fewer residents, and therefore, fewer reports. Based on rates of infection, Colorado -- with nearly nine times the human population of Wyoming -- comes second to its northern neighbor, Pape said.
Also, states are not federally mandated to report cases. In many states, if serious symptoms did not occur, the case was not documented, Pape said.
With uncertainty about this year's spread of West Nile Virus, officials aren't taking any chances.
"We all know what happened in Eastern Colorado last year," Routt County Extension Agent C.J. Mucklow said. "We need to be prepared for that."
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