Potential for West Nile virus has county on the offensive


By Roger Showley

August 14, 2008
From a sheriff’s helicopter, every San Diego neighborhood sparkles with patches of light-blue backyard pools and spas, symbols of the good life in the Sun Belt.
Only these days, an increasing number of pools are turning slimy green from the algae that grow once owners turn off the filters to save cash or lose their properties through foreclosure. On weekly flyovers, county environmental health officers have spotted nearly 900 of these “green” pools since May.

In this case, green is not good. The algae attract mosquitoes that lay their eggs on the surface, and in a few days adult insects emerge, bothering residents and potentially spreading the deadly West Nile virus.

“If people don’t tell us they have a green pool, they are at risk to get West Nile virus,” said Chris Wickham, one of 40 county staff members combating the virus and other diseases borne by mosquitoes, rats and other sources or “vectors.”

Last year, the county’s vector-control program received 2,149 mosquito-related complaints or service requests. To get a handle on all potential mosquito breeding grounds, the county has stepped up its aerial surveillance and visits to properties with green pools.

So far this year, the number of green pools sighted by helicopter has sometimes reached 80 to 100 in a two-or three-hour flight compared with 20 a year ago, Wickham said. Many are found in Chula Vista, Escondido and Oceanside, where foreclosures have been high.

“It sure seems like there are more green pools out there than last year,” Wickham said.

The problem is not restricted to San Diego County, officials said. Urban counties throughout the state are reporting more problem pools. And in Clark County, Nev., home of Las Vegas, the total so far this year is 2,000.

Bill Reisen, a research entomologist whose lab at the University of California Davis is testing 1,000 groups of mosquitoes weekly for West Nile virus, said swimming pools may be a growing source of virus-carrying mosquitoes. Dry conditions should have eliminated the normal breeding grounds found in wetlands, riverbeds and other such habitats.

“The end of the issue will be to have someone buy these houses and take care of the pools properly,” Reisen said.

Such was the case of a property on Tait Street in Linda Vista seen by Wickham last week. The telltale green tinge was spotted from the air, so he went out Saturday to investigate and found a for-sale sign outside the property, which was tented for termite control.

As allowed by law, Wickham entered the backyard, deposited about a half-dozen “mosquito fish” to feed on mosquito larvae and left a notice that reads, “Mosquito Fish at Work – Do Not Add Chemicals,” and asks the residents to contact the vector-control program for more details.

“Right now, our charge is to protect the public health,” Wickham said. “Our cause is to kill every mosquito we can – no mercy, take no prisoners.”

Coincidentally, the 1,850-square-foot property closed escrow yesterday, and the new owner plans to empty the pool and cover it, said the listing agent, Ellen Wang of Re/Max Associates.

Next door, Wickham also found a green pool in the backyard of a home that is occupied but where the owner did not respond to his knocks at the door. He threw a handful of mosquito fish over the fence in the hope that any breeding problem would be controlled.

“As far as I’m concerned, that’s now a pond, not a swimming pool anymore,” Wickham said.

Jean Listar, a neighbor, said the owner’s wife had died recently and that he had stopped maintaining his landscaping and pool. Listar said she had not seen any mosquitoes – “not yet, anyway.”

The county has been fighting mosquitoes for more than 30 years, and since 1989 has charged a mosquito-, vector-and disease-control assessment on property tax bills to cover the costs. This year the charge is $7.92 per house – or $1 more for coastal properties – and an equivalent amount for other property types.

The current budget of $893,609 supports a staff of 28 full-time and 12 seasonal workers who do surveillance, visit homeowners and conduct educational campaigns to alert the public to the danger of West Nile virus and other diseases. The budget includes $25,000 for flyovers in sheriff’s helicopters at the rate of $700 per hour.

The virus, first detected locally in 2003, infected 15 humans in the county last year and three so far this year. Symptoms resemble the flu but can become severe, resulting in polio-like disability and sometimes death. There have been no deaths so far in San Diego County.


Information: The county Department of Environmental Health operates the region’s vector-control program with the goal of eradicating mosquitoes carrying the West Nile virus and other diseases. Information is available at (888) 551-INFO and sdfightthebite.com. The California West Nile virus Web site is westnile.ca.gov.

Free fish: Free mosquito-eating fish are available from the vector-control program’s office at 9325 Hazard Way, Kearny Mesa; (858) 695-2888.

Personal protection: Officials recommend that residents protect themselves by using insect repellent containing the active ingredient DEET, wearing long-sleeve shirts and long pants, repairing window and door screens to keep mosquitoes outside, and dumping containers of stagnant water. Mosquitoes generally are active from dusk to dawn.


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