Fogging for mosquitoes to continue in Madera

The Fresno BeeJune 21, 2013 

Madera will be spraying early today and Sunday for a type of mosquito that can spread dengue and yellow fever, an official said.

Fogging crews will begin at 4 a.m. and typically will be done by 8 a.m.

The weekend mosquito fogging will be targeted in a nine-block radius around the Arbor Vitae Cemetery in west Madera, said Leonard Irby, manager of the Madera County Mosquito and Vector Control District. That's the area where the mosquitoes were first found in traps about a month ago. On Thursday, the mosquitoes turned up in traps in Clovis, northwest of Shaw and Temperance avenues.

Two fogger machines will be in use this weekend. A special fogger to attack the larvae or immature Aedes aegypti mosquito will be available later in the week, said Irby.

On Monday, district employees will take the mosquito fight door-to-door, Irby said.

The mosquitoes are the first known to have been found in an inland area of California and the first time they have shown up in the central San Joaquin Valley, said Vicki Kramer with the California Department of Public Health.

There have been no established populations in the state, she said. However, the mosquitoes have been found in the southeastern United States and a few places in Arizona, she said.

So far, none of the mosquitoes trapped in the Valley has been found to carry either tropical disease, whose symptoms include fever, severe headaches and body aches. In severe cases the diseases can be fatal.

But the mosquito, known for being a day-biter, is an efficient carrier of the diseases, so eradicating the pest before it can get a toehold in an area is a priority, Kramer said.

Eliminating the mosquitoes won't be an easy task. Unlike mosquitoes that cause West Nile virus, which breed in large pools of water, the Aedes aegypti prefer to lay eggs just above the water line on the inside of containers that hold water, Kramer said. The eggs can survive for months and the container can dry out. Once the eggs are flooded, they hatch into larvae and develop into mosquitoes.

The eggs can be laid in backyard potted-plant containers, saucers, buckets, pet dishes, bird bathes, flower vases -- and in cemetery flower containers, she said. It's not known how the mosquitoes got to Madera and Clovis, Kramer said.

"The public's help is really needed to dump out standing water on their property," she said.

Finding the mosquitoes hidden in back yards is essential, said Steve Mulligan, manager of the Consolidated Mosquito Abatement District that covers most of Clovis.

The public's cooperation is needed in reporting the mosquitoes, Mulligan said. The insect, which is dark brown or black, has distinctive white markings and is known to bite during the day. Consolidated will be doing more trapping to determine if mosquitoes are in other areas of Clovis, but the initial trapping was triggered after residents complained about mosquito bites, he said. "We went out and found it."

People also will need to allow district workers into back yards, Mulligan said. "It's going to have to be a door-to-door campaign to find out where it is and try to kill the immature and adults residence by residence."

Irby said a small crew will go to homes in the affected Madera area on Monday, but going door-to-door "is very time consuming and we don't have enough personnel to do that for any length of time," he said.

He's hopeful buying the special fogger -- only two are in California -- to kill larvae will pay off. The district paid $7,500 for the unit, which was used for experimental applications in San Mateo, he said. Brand new, it would cost about $15,000. The second fogger is in Los Angeles.

The larvicide being sprayed is safe, Irby said. "It's expensive, but it's safe."

Fighting this rogue mosquito is biting into the district's budget for West Nile virus eradication, Irby said. "Our budget is pretty tight as it is and the last 10 days cost $20,000 to $30,000 for equipment and pesticides and for overtime for employee."

So far this year, no mosquitoes infected with West Nile virus have been found in Madera County, Irby said. West Nile activity has been detected in Fresno, Kings and Tulare counties so far this year, according to the state.

Tips for avoiding mosquito bites

-- Dump standing water in back yards

-- Wear mosquito repellent when possible

-- Wear long-sleeved clothing to protect from bites

-- Make sure doors and windows fit tightly

-- Report any mosquitoesto local mosquito control district

The reporter can be reached at (559) 441-6310, banderson@fresnobee.com or @beehealthwriter on Twitter.

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