REGION: Too many pools and too few fish; that bugs county vector control

By SARAH GORDON - Staff Writer | Thursday, July 17, 2008 7:10 PM PDT ∞

NORTH COUNTY ---- Facing a record number of slimy swimming pools behind foreclosed homes and a shortage of the fish used to prevent the mosquito colonies that inhabit them, the county employees who combat disease-carrying pests have their work cut out for them.

Their challenges come amid concerns that the mosquito-borne West Nile virus is unusually active in the county this year.

Swimming pools that have gone green with algae because of inactive filters are the perfect breeding ground for mosquitoes, health officials warn. With the number of foreclosed homes in the county doubled over last summer, there are more abandoned, unfiltered pools than ever before.

"As the foreclosure dilemma has gone up, the number of 'green' pools we're seeing has gone up," County Vector Control Program Director Kerry McNeill said.

Standing water that breeds mosquitoes has been linked directly to human cases of the West Nile virus. All 15 people who developed the virus in 2007 had standing water sources in their backyards, McNeill said.

To find the algae-choked, abandoned pools referred to as green pools, county employees search by helicopter, McNeill said. In about a half-dozen flights since May, they have found 467 green pools, she said. Additional pools have been reported by neighbors.

The number of pools found last year at this time was not immediately available for comparison, but McNeill said the department's 21 technicians are responding to significantly more cases this year than ever before.

For the last three weeks, technicians have been working weekends to treat all the pools, she said. Last year, no overtime was spent on the work.

Placing about 10 larva-eating mosquito fish in a pool is one of the most effective ways to prevent a mosquito colony from forming, vector control officials say.

But the fish are in short supply this year. The county's Barstow-based supplier has not yet delivered the 425,000 fish the county ordered.

Vector control spokesman Chris Conlan said the supplier had offered several reasons for the delay.

"He's saying the cooler weather earlier this year and pollutants in the water from the fall wildfires killed off some of the stock," Conlan said.

The fish delivery, expected about a month ago, is now expected in early August, Conlan said. The county has budgeted $15,000 for the purchase.

Conlan said the shortage wasn't hampering the county's efforts to eliminate the mosquito colonies.

Last year, vector control technicians had as many fish as they needed every day, and residents could pick up the fish free at 16 pet stores and nurseries around the county. Residents were encouraged to add the fish to any standing water source, including decorative fountains, birdbaths or planters.

Conlan said the fish are still available to residents, just not at the distribution centers.

"What it's really done is kind of forced us to be a little more picky about how we give them up," he said.

Residents now must come in person to County Vector Control at 9325 Hazard Way to pick up fish or call one of the department's technicians to evaluate their need.

On Thursday, Ken Wilson, one of the county technicians, went to a vacant house on Pala Road in Oceanside to add 10 fish to a green pool. He had evaluated the pool a week before but hadn't had enough fish available that day to finish the job, he said.

On Thursday, with about four more Oceanside houses on his list, he was careful to take only the 10 fish from his plastic bucket.

"We've got the fish, but we're being careful how many we use," he said.

After the guppy-sized, fresh-water fish plunked from his net to the slimy water, they skittered in a school along the pool's stucco wall, where larvae take up residence, Wilson explained. The 10 starter fish will multiply quickly and successfully prevent mosquito colonies, he said.

Although most of Wilson's work involves treating pools, once a week he said he visits former customers to harvest their excess fish. He also traps the fish, which thrive in some of the county's storm drains and creeks.

McNeill said the department had picked up fish from about 10 residents this week, but it hasn't made much of a dent in the fish deficit.

West Nile virus is transmitted from birds to mosquitoes to people. This year, 96 birds have been discovered dead from the virus, compared to six at this time last year. In June, a colony of mosquitoes carrying the virus was discovered in Hubbert Lake in northern Oceanside. No human cases have been reported. The disease can cause fever, brain damage and death, though it is fatal in less than 1 percent the cases.

The best way to avoid contracting the virus is to avoid being bitten ---- by wearing insect repellent and protective clothing, McNeill said.

"At this point, we know the virus is here," she said. "Everyone should be protecting themselves this summer."

For more information on preventing mosquito colonies or West Nile virus, call (888) 551-INFO or visit www.SDfightthebite.com.

Contact Staff Writer Sarah Gordon at (760) 740-3517 or sgordon@nctimes.com.