Mosquito counts fell, but anxieties continued to run high Wednesday as the Sacramento-Yolo Mosquito and Vector Control District gave the county's northern areas a third consecutive aerial spraying of insecticide and prepared to move south today.
"We are going to spray Thursday, Friday and Saturday in the south areas if weather permits," said Dave Brown, manager of the district.
The massive spraying project is being done to combat West Nile virus, which is carried by mosquitoes. The quickly assembled operation has drawn praise from people worried about the rapid spread of the virus, but heavy criticism from others concerned about potential health hazards from the spray.
Sacramento County's count of human infections stood at 26 Wednesday, marking the highest number among California's 58 counties.
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Placer County on Wednesday reported two new human cases, bringing its total this year to three, while Yolo County reported its first human case this year.
According to Brown, the aerial spraying is hitting its mark.
The district, he said, has two types of mosquito monitoring systems in place.
Trap results - which indicate the actual presence of mosquitoes in a geographic area - showed close to a 50 percent kill rate in some traps after Tuesday night's aerial spraying. The goal is to reach 70 percent, which is considered a breaking point in the transmission cycle of the virus, Brown said.
In addition, mosquitoes serving as guinea pigs were placed in mesh cages throughout the affected areas. The caged monitoring showed kill rates of 30 percent to 100 percent, Brown said.
Another test conducted by a UC Davis researcher found evidence the spraying has not harmed small creatures in its path.
Crickets, goldfish, pill bugs and other insects set out overnight in Sacramento's mosquito-spray zones survived just as well as comparison groups protected from the spray, said Walter Boyce, director of the university's Wildlife Health Center.
"What we have here is pretty strong preliminary evidence that the spray didn't have any effect on these organisms in these locations," he said.
Vector control officials have emphasized that at the small dosage being applied, the product - Evergreen Crop Protection EC 60-6 - is lethal to mosquitoes and some small insects, but not harmful to people, animals, fish, swimming pools, gardens or waterways.
Those assurances have done little to calm the public.
Since Monday, when the spraying began, people have flooded the vector district, media outlets and the offices of local officials with calls, e-mails and letters.
Many have been outraged they are being sprayed without their consent, and that they had little advance notice.
The district announced Aug. 4 that the infection rates of people and mosquitoes had spiked and required the immediate aerial assault.
Four days later, the spraying began, and by Monday evening, the vector district had received 20,000 phone calls and 20,000 hits on its Web site. The interconnected phone and Internet systems were so overloaded that the Web site crashed. Since then, five more people have been brought in to pick up calls, Brown said.
Among the emerging concerns has been whether some of Sacramento's most vulnerable people - non-English speakers and the homeless - have been adequately notified. In some places, individuals were stepping in to fill in the gaps.
Minh Thi Tran, a talk show host with Vietnamese radio station TNT, said she learned of recommended precautions while watching Channel 10 (KXTV) Tuesday evening and realized many of her community's elders probably didn't have the information.
Tran planned to spread advice on her show Wednesday evening, instructing people to stay inside and bring in toys during sprayings. "We are very proud to bridge the gap," she said.
Others had the homeless on their minds.
Joy Doyle, a 73-year-old resident of south Sacramento, spent most of Monday calling service providers and public officials to find out whether homeless people had been warned. Her 56-year-old daughter is mentally ill and homeless, and Doyle was worried.
"It just occurred to me that we have this whole population of fragile people who are pretty much ignored," Doyle said.
At Friendship Park, a gathering spot for the homeless just north of downtown Sacramento, staff member Vera Barter made several announcements this week about the spraying but didn't recommend anyone stay inside. "That's a little cruel," she said.
According to Brown, the vector district sent out postcards in English - some of which were not delivered until Tuesday - but could not have afforded more communications.
"We don't have the resources to notify in every language," he said, adding that the district mainly relied on the media to get the word out.
People also were increasingly unnerved by the many dead birds that have been turning up - victims not of the spraying but of West Nile virus.
Birds play a key role in the spread of West Nile. They are a favorite target of mosquitoes. If bitten by an infected one, birds can become "reservoirs" for the virus, passing it along to uninfected mosquitoes that bite them.
The state Department of Health Services is tracking bird deaths and wants to hear about every one, said Vicki Kramer, chief of the department's Vector Borne Disease Program. People can call (877) WNV-BIRD (968-2473) or report incidents at www.westnile.ca.gov.
After that, people should dispose of the birds in their garbage cans.
Dr. Vicki Giles, Sacramento County's public health veterinarian, said more and more horses and gray tree squirrels also are turning up with the virus and dying. Mosquito control officials hope to stop that pattern, along with human infections, with the aerial spraying.
On Tuesday, the application in the north area occurred between 8:45 p.m. and 11:10 p.m., said Dan Markowski, who is heading the operation for Vector Disease Control, Inc., the Sanford, Fla. firm doing the aerial spraying.
About 50,000 acres were covered by two twin-engine planes, covering most of the county north of the American River. The area running immediately north of the American River was treated by ground spraying.
The same areas received similar treatments Wednesday night.
Tonight, the operation is expected to move south. According to the district's Web site, the general boundaries are Interstate 5 on the west, just east of Watt Avenue on the east, a bit south of Elk Grove Boulevard on the south, and just south of the American River to the north.
Downtown Sacramento will not be aerially sprayed because of the numerous tall buildings. Ground spraying will fill in the gaps, Brown said.
Several individuals contacted The Bee to say the spraying had made them feel ill or exacerbated allergies.
Representatives from the UC Davis Medical Center, Mercy General and Kaiser Permanente Sacramento Medical Center said they had no increase in people seeking medical help related to the application.
Officials say residents in the spray zone are not at risk and do not need to take precautions for themselves, pets or 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 may 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.
The killing agents in the insecticide - EverGreen Crop Protection EC 60-6 - are pyrethrins, extracted from chrysanthemum flowers. They are among the environmentally friendlier pest control options, killing insects on contact yet quickly disintegrating in sunlight, state regulators said. People expose themselves to much higher levels of the same chemicals in spraying their homes, lawns and gardens with common insecticides. Pyrethrins also are contained in lice shampoos.
The insecticide also contains piperonyl butoxide. Though the U.S. Environmental Protection Agency has classified the chemical as a "possible" cancer-causing agent in humans and mammals, the agency rates it "low to very low" in toxicity.
West Nile prevention tips
To reduce the risk of catching West Nile virus, the Sacramento-Yolo Mosquito and Vector Control District recommends:
Use an effective mosquito repellent containing ingredients such as DEET, Picaridin or oil of lemon eucalyptus.
Repair tears in door and window screens.
Drain standing water.
Wear long pants and long sleeves outdoors when practical.
Avoid being outside at dawn and dusk when mosquitoes are most active.
The mosquito control district board will meet at 6:30 p.m. Thursday at the county supervisors chambers, 700 H St., to solicit public comments and evaluate the effectiveness of the aerial spraying.
About the writer:
- The Bee's Deb Kollars can be reached at (916) 321-1090 or firstname.lastname@example.org. Staff writers Jocelyn Wiener and Carrie Peyton Dahlberg contributed to this report.