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Prime time for mosquitos, spread of West Nile virus

Plentiful snowmelt, a rainy spring and the recent onslaught of very warm weather have combined to create the perfect breeding environment for mosquitoes, the pesky insects that spread West Nile virus.

Although no human cases of the virus have been reported in the state this year, Northern and Central California are ripe for a major outbreak, health officials announced Monday.

"It was already predicted that Northern California and the Sacramento Valley were going to have a tough year, but now, Mother Nature is helping that along," said David Brown, manager of the Sacramento-Yolo Mosquito & Vector Control District. "We're getting anxious."

So, apparently, are some state legislators.

At a hearing of the Senate Select Committee on West Nile Virus on Monday afternoon, Sen. Dean Florez grilled state health officials about whether California is ready for what is predicted to be the worst year yet for the sometimes deadly disease.

Florez, D-Shafter, pummeled them with questions about the capacity of the state's hotline for reporting dead birds, its educational outreach to schools and to non-English speakers, and its use of scarce funds dedicated to combat spread of the disease.

Vicki Kramer, chief of the vector-borne disease section at the state Department of Health Services, said the state is better prepared this year than in 2004, when California bore the brunt of the illness nationwide.

The bird hotline received 150,000 calls last year, with 50,000 in August alone. "This year we have stacked up much earlier and expanded our hotline hours," she said. West Nile virus is transmitted to humans by the bite of an infected mosquito. Mosquitoes, in turn, pick up the virus from infected birds.

While state officials want residents to continue to report dead birds, callers in some areas will be told that the bird will not be picked up and to dispose of the animal themselves.

"For birds that fit the criteria for testing and in areas where local agencies still want this information, we will do that testing," said Anne Kjemtrup, a state research scientist. "We have also expanded this year and many local agencies can do the testing themselves."

Already in 2005, the virus has shown up in 21 California counties, mostly in dead birds, as well as in a pool of mosquitoes in Orange County and in a sentinel chicken in San Bernardino County. Sentinel chickens, which do not migrate, are used throughout the state to detect West Nile virus.

"We expect (human virus activity) soon, particularly with increasing temperatures and a lot of standing water," Kjemtrup said. "We have a pretty volatile situation."

At UC Davis, where scientists analyze dead birds and mosquitoes for evidence of the virus, it's clear the cycle is revving up again.

Leslie Woods, a veterinary pathologist who coordinates the testing program, said her lab already is seeing 20 to 40 dead bird tissue samples per day.

"I imagine that as soon as it gets warmer and we start seeing more mosquitoes that we're going to be seeing more birds," Woods said.

At the peak of summer 2004, the lab was receiving some 80 birds a day, Woods said, with one hectic day topping out at 115 birds. All told last year, 3,232 dead birds from throughout the state were found to be infected with the virus.

Kramer said state efforts to monitor and control spread of the virus will be enhanced with the recent addition of $1.6 million from the federal Centers for Disease Control and Prevention. She added that Gov. Arnold Schwarzenegger has proposed in his revised 2005-06 budget $12 million to enhance mosquito control programs in local jurisdictions.

Officials also took the opportunity Monday to remind individuals how they can help prevent mosquito breeding and protect themselves from infection.

"Right now, it's really important to go around your home and look for any sources of standing water and be sure those areas are drained, such as clogged rain gutters and pots full of water," Kjemtrup said. "Make sure you have tight-fitting screens on your doors and windows. And if you go out, make sure you wear products that contain DEET."

In Roseville on Monday, the Placer Mosquito Abatement District laid out its tools of attack, including tiny fish that go on mosquito-larvae feeding frenzies.

The district will deliver tanks of mosquito fish to residents who have backyard ponds, water gardens or fountains.

The district also highlighted a newly approved bug repellant - oil of lemon eucalyptus. The plant-based repellant, an alternative to DEET that can provide up to six hours of protection, has been approved by the U.S. Environmental Protection Agency.

Want to know more?

To submit questions about West Nile virus, e-mail or mail your question to The Sacramento Bee Newsroom, Attention Bill Enfield, Box 15779, Sacramento, CA 95852. Please include a phone number. The Bee periodically will publish the answers to questions.

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About the writer:

  • The Bee's Dorsey Griffith can be reached at (916) 321-1089 or Bee staff writers Edie Lau and Jennifer Morita contributed to this report.