Mosquito danger growing in neglected Valley pools

Mosquito control officials in the central San Joaquin Valley say there are more green pools than ever in backyards, serving as perfect breeding grounds for mosquitoes carrying West Nile virus.

Algae-laden pools have been ground zero for mosquitoes since default notices and foreclosures skyrocketed during the recession, but mosquito fighters had hoped that the spate of unkempt pools would ease.

Not so, they say.

“It’s continuing and it seems like it just increases year after year,” said Steve Mulligan, manager of the Consolidated Mosquito Abatement District, which covers most of Clovis.

Valley mosquito-abatement districts have had to resort to aerial surveillance to keep tabs on murky pools and even subscribe to foreclosure-tracking services.

Last year, in a flight over Clovis, 1,300 suspicious pools were found that had not been identified in prior years, Mulligan said. Of those, 600 were breeding mosquitoes when workers inspected them, he said. Consolidated has yet to do a flyover this year, but Mulligan expects as many, if not more, suspicious pools will be found.

“It’s an ever-changing number, but the number is always increasing,” he said.

There have been no human cases of West Nile virus reported in California this year, but there are more reports of infected mosquitoes than at this time last year.

Last year at this time, mosquitoes from five traps showed infected insects. This year, mosquitoes from 91 traps have been found, said Vicki Kramer, chief of the vector-borne disease section at the California Department of Public Health.

Of the 91 positive samples, 50 were in Sacramento County, Kramer said. Kern and Riverside counties have had substantial numbers of infected mosquitoes, as well.

Fresno County has had infected mosquitoes found in three traps.

Last year, 158 people in California were infected by West Nile virus and nine died.

There were no fatalities in the Valley, but Fresno County reported nine cases and Tulare 11. Madera had two cases and Kings had one.

Mosquito-control technicians have been busy the past month stocking mosquitofish in stagnant pools to try to outrace the mosquito-breeding season, which kicks into high gear in warm weather.

But it’s a never-ending job.

In Fresno, 921 pools have been treated or are targeted for treatment, said Tim Phillips, manager of the Fresno Mosquito and Vector Control District.

By the end of the season, he expects the number to grow to more than 1,000, which is about the number treated last year.

Workers on Monday canvassed a neighborhood known to have mosquito problems, leaving 250 handbills for residents asking them to notify the district of any neglected or abandoned pools.

“We found four pools we didn’t know about,” Phillips said.

“You think we’re on the [economic] upswing and it slows down, and here comes more [foreclosures],” Phillips said.

The Delta Vector Control District in Visalia took to the air at the end of April to locate algae-coated pools.

The aerial surveillance of 52 square miles found 1,100 green pools, said General Manager Mike Alburn.

Last year, about an equal number of suspicious pools were located by air, he said.

Besides aerial surveillance, mosquito fighters at the Delta district subscribe to foreclosureradar.com, which tracks foreclosure activity.

While the number of homes in foreclosure has remained fairly stable this year, this May saw an uptick in default notices in Fresno and Tulare counties, according to foreclosureradar.com.

“The first bank letter to a homeowner lets us know that property has got an issue,” Alburn said. “We sort that list by those that have a swimming pool and it gives us a heads-up to start paying attention.

“As long as we have foreclosures, that’s our problem.”

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West Nile facts

How it’s transferred: People become infected when they are bitten by mosquitoes that become infected when they feed on birds carrying the virus.

Symptoms: Complications from the virus can be fatal, but most people who are infected do not become ill. About 10% to 15% have moderate symptoms such as a headache, fever or body ache and fewer than 1% of people infected develop serious neurologic illnesses such as encephalitis or meningitis.

Treatment: There is no vaccine for humans, but a vaccine for horses is available through veterinarians.

Protection:People should use mosquito repellent or wear protective clothing if they’re outside at dawn or dusk. The state also wants people to report dead birds at (877) 968-2473 or westnile.ca.gov.

By Barbara Anderson