West Nile virus or West nil virus?

The harbingers of plague have called it quits for the season, and local health experts met yesterday to discuss what they have learned this summer about the deadliest animal known to man – the mosquito.Malaria and dengue fever have for years been its weapons of choice, but Tuesday the focus was on one of the bug’s newest pathogen, West Nile virus.As early as February, Pitkin County and city health experts began preparing for what was thought to be an explosive year for West Nile cases. Human cases of the virus, which is transmitted to humans through mosquito bites, had increased exponentially in Colorado over the past few years. This summer proved to be a surprise, however, with only 274 people infected in the state, compared to 3,000 in 2003.West Nile virus produces symptoms in about 20 percent of infected people. Only 1-in-150 patients become seriously ill. In rare cases, West Nile can cause meningitis and encephalitis, two extremely dangerous forms of brain inflammation. The virus appears in Colorado from April to mid-September during mosquito-hatching season. Overall cases of the virus were down in Colorado; more than 50 percent of the cases were on the Western Slope. Although Pitkin County reported no human cases, a dead bird recovered near Lazy Glen tested positive for the virus in August.Health experts said in a joint meeting with the Pitkin County commissioners yesterday that weather seems to be the determining factor in this year’s drop-off.”We learned this summer how important weather is,” West Nile specialist Lara O’Leary said. “It was a much cooler summer this year than last. Mosquitoes don’t breed well in cooler temperatures.”Health officials also laid out further measures they will implement next year to control the disease. Along with continued monitoring of mosquitoes, health officials will also implement a larvicide program in certain hot spots identified in this year’s monitoring.Eben Harrell’s e-mail is eharrell@aspentimes.com