FRESNO -- 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 the potentially lethal 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. They subscribe to services that track foreclosures.
Last year, in a flight over Clovis, 1,300 possibly problematic pools were found that had not been identified before, 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, such 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 reported in California this year, but there are more reports of infected mosquitoes than at this time last year, when mosquitoes from five traps showed infected insects.
This year, infected mosquitoes have been found in 91 traps, said Vicki Kramer, chief of the California Department of Public Health's vector-borne disease section.
Of the 91 positive samples, 50 were in Sacramento County, Kramer said. Kern and Riverside counties have also had substantial numbers of infected mosquitoes.
Fresno County has had infected mosquitoes found in three traps.
Last year, 158 people in California were infected by West Nile virus. Nine died.
There were no fatalities in the Valley, but Fresno County reported nine cases and Tulare had 11. Madera had two and Kings had one.
Mosquito-control technicians have been busy over the past month, stocking mosquitofish in stagnant pools to try to outrace the mosquito-breeding season, which kicks into high gear in warm weather.
It's a never-ending job.
Infected bird found
In Merced County, a dead bird found in the Atwater area last month tested positive for West Nile virus, Merced County officials said this week.
No mosquitoes have tested positive for West Nile Virus in the county, according to Allan Inman, director of the Merced County Mosquito Abatement District.
But that could change.
This week, the district began focusing on a two-mile radius around the area where the bird was found.
While flying over the area, Inman looked for standing water with vegetation in it. He spotted three draining basins from the air and half a dozen swimming pools people hadn't taken care of.
He set traps for mosquitoes and has sent some off for testing.
"It takes only one bite by the right mosquito," he said.
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."
There is no vaccine for humans, but a vaccine for horses is available through veterinarians.
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.