Sacramento County mosquitoes have a new ally: the Delta breeze.
Brisk winds are hampering efforts by the Sacramento-Yolo Mosquito and Vector Control District to conduct aerial spraying on up to 66,000 acres in southern Sacramento County. On Thursday, the winds cut spraying short. Friday saw no aerial spraying at all because of the breeze. Saturday night, spraying again was canceled in the face of steady winds. Officials said they would try again today.
Frustrated district officials acknowledge the uncertainty is a problem because the public doesn't know from night to night whether spraying will actually occur - and whether to keep windows closed and avoid exposure.
The district is doing the treatments to stop the spread of West Nile, which is conveyed by infected mosquitoes.
Earlier last week, three nights of carpeting about 55,000 acres of Sacramento County north of the American River with a fine mist of pesticide drastically reduced mosquitoes, according to Dave Brown, manager of the vector control district. Traps in the north area showed mosquito kill rates of between 40 percent and 80 percent following the three nights of spraying.
Officials worry that, if the aerial spraying efforts south of the American River don't resume soon, mosquitoes will continue to thrive and spread West Nile. And Brown said forecasts indicate the winds could cause problems into this week.
"I am extremely concerned about it," said Brown. "We are leading the state right now in human cases. We have a very high infection rate."
As of late Friday, Sacramento County had 36 confirmed human cases of West Nile, out of 174 statewide. Four people statewide have died from the virus so far this year. The latest victim was Jim Rodgers, 86, a World War II veteran who lived in the town of Acampo, north of Lodi.
The decision to do aerial spraying has angered some residents, who are concerned about the risks posed by pesticide exposure.
Dr. Bill Durston, president of the Sacramento chapter of Physicians for Social Responsibility, is among those who have questioned whether the vector control district did an adequate analysis of risks and benefits before deciding to spray. He maintains there is no emergency and says, "We don't know if it is truly an epidemic or just detecting cases where we used to not know what it was."
District and county health officials have said that, in the light dosage being applied, the insecticide is safe for people and animals, and that the threat posed by West Nile far outweighs the risks posed by spraying.
Many residents agree, and scores whose neighborhoods are not being sprayed have complained at being left out.
Health officials have advised that people concerned about exposure stay inside between 8:30 p.m. and midnight on nights when aerial spraying takes place. But wind conditions could make it difficult for vector district officials to let residents in the south county know when spraying will occur in the coming week.
Judy White doesn't want to be one of those caught outside unawares. A Fruitridge resident, she thinks the spraying "is necessary but not great." She wants to know when the spraying will occur so she can take precautions.
"I'd like to know so I could get the animals in and rinse off the stuff I don't take in," said White as she sat in Lawrence Park.
James Johnson has similar concerns. He has four kids living with him near Fruitridge.
"I wouldn't want them to be out while they were spraying," he said, waiting at a bus stop next to Fruitridge Community Park.
Brown said he understands the concerns but has few options. Wind conditions are so variable, it's hard to know until the planes take off whether the spraying can go forward.
A slight breeze usually doesn't hamper aerial spraying, said Dan Markowski, who is heading the aerial spraying operation for Vector Disease Control, the Florida-based contractor hired by the district. Specialized equipment allows pilots to predict where the spray will land, even as they fly about 300 feet above ground.
But when the wind climbs above 10 mph, things get tricky. "It's very likely that the product will go out of the control zone," Markowski said.
With planes grounded, vector control crews have been doing more spraying from trucks, officials said. But since ground crews tend to stick to the roads, such efforts are not considered a replacement for aerial spraying.
If wind conditions remain adverse for several more days, Brown said, the district will re-evaluate mosquito prevalence and determine how to proceed.
In the meantime, Brown repeated requests for residents to take personal action. "Do what you can to reduce exposure to mosquitoes," he said. He urged people to wear repellant and stay indoors when mosquito activity is high.
WHAT TO DO IN SPRAY ZONES
Officials say residents in the spray zone are not at risk and do not need to take precautions for themselves, for pets or for livestock. For those who remain concerned, they're suggesting ways to reduce exposure:
* Stay inside and keep doors and windows closed between 8 p.m. and midnight. The mist stays in the air up to 90 minutes after release.
* Turn off air conditioning or ventilation systems during spraying.
* Bring patio furniture, toys and pets indoors for the evening. Cover items left outside.
* Remove shoes before coming inside until spraying ends.
* Wash outdoor furniture and other items people might touch. But don't create pools of water that could become mosquito breeding grounds.
* Fruits, vegetables and herbs from gardens should be washed but will be safe to eat.
* Swimming pools do not need to be covered and will be safe for swimming after the applications.
For more information, call (800) 429-1022 or check www.fightthebite.net.
About the writer:
- The Bee's Phillip Reese can be reached at (916) 321-1137 or firstname.lastname@example.org.