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| March 24, 2006 Mosquito Season Early By Ali Bay DAVIS — Mosquito experts from the University of California and mosquito abatement districts warn that mosquito season and the West Nile virus are arriving earlier this year. Culex mosquitoes, the principal carriers or vectors of West Nile, are usually the most active in California from April through October, but the unseasonable springlike weather awakens them like an alarm clock from their winter semi-hibernation, said Gregory Lanzaro, entomology professor and director of the UC-Davis Center for Vectorborne Diseases. "These conditions are like their wake-up call," Lanzaro said, who is also director of the UC Mosquito Research Program. "The mosquitoes that were infected with WNV before they went into their semi-hibernation, or diapause, still have the virus. They're loaded and ready to go." The disease, transmitted by the bite of an infected mosquito, last year killed 18 people in California and infected more than 900 others throughout the state. Health officials found the virus in all 58 counties. Last year's outbreak in California was not an isolated case, said UC Davis medical entomologist Robert Washino. "It's a preview of what's to come unless we take proactive actions." He predicts heavy snowpacks in the mountains and a series of hard-hitting storms in the valley with abnormally high rainfall, and springlike weather will cause mosquito populations to soar this year. In February the California Department of Food and Agriculture said that warm weather renews the threat of the virus, serving as a reminder to horse owners to make sure their animals are vaccinated. Last year, 456 horses in the state were known to have contracted the disease, with 200 deaths. In the great majority of those cases the horses were either not vaccinated or vaccinated improperly. "Outbreaks of West Nile virus are expected to continue this year," said California State Veterinarian Dr. Richard Breitmeyer in a prepared statement last month. "Horse owners should contact their veterinarians as soon as possible to ensure current vaccination status, so that horses will have maximum protection against the disease." Signs of West Nile virus include stumbling, staggering, wobbling, weakness, muscle twitching and inability to stand. Horses contract the disease from carrier mosquitoes and are not contagious to other horses or people. Not every horse exposed to the virus will die. UC officials say it's important to remove sources of standing or excess water, which can become mosquito breeding grounds. Empty, turn over, throw out or cover all containers accessible to mosquitoes, and take precautions with fish ponds, birdbaths and fountains, entomologists suggest. First discovered in the West Nile district of Uganda in 1937, West Nile virus was identified in New York in 1999 and in California in 2002. For the last two years, California's WNV deaths and infection rates led the nation. Sacramento County, considered a national hot spot for the virus, tallied a record 175 human cases in 2005.
Contact: |
UC Mosquito Research Program - Department of Entomology - UC Davis - UC Agriculture and Natural Resources
One Shields Avenue, Davis, CA 95616
© 2006, The Regents of the
University of California.
Comments or Questions: Nancy Dullum, Program Assistant
Last updated:
03/28/2006