Foreclosure Fallout: Public Health Threat

May 21, 2008 — -- California's Contra Costa County, in the suburbs of San Francisco, is the heart of foreclosure country. Its streets are dotted with examples of the American dream abandoned.

Thousands of sprawling ranch homes stand unoccupied, along with thousands of now stagnant swimming pools. And a nasty unforeseen consequence of the housing downturn has bubbled to the surface in those pools: mosquitoes.

"Pools, when they aren't maintained, there are nutrients in the water and you get the sun producing energy and the mosquitoes will use the bacteria or the energy to produce," said Chris Miller, a biologist with the Contra Costa Mosquito Vector and Control District.

But these mosquitoes are not just a mere nuisance, they're also potentially dangerous.

"They transmit West Nile virus," said Miller, "and that is why we are so concerned with these pools and the foreclosure issue. It can be a real threat to public health."

Miller thinks he has the solution to the mosquito problem. His answer is a tiny fish with a big name: Gambuzia Affinis.

"These fish work 99 percent of the time," Miller said.

The newest soldiers in the foreclosure war grow no more than 2½ inches, but they are mean. These cannibalistic fish also love to eat mosquitoes -- lots of them.

"They are surface-oriented fish, so they feed on surface-oriented insects," Miller said. "They feed primarily on mosquito larvae, which go to the surface to breed, so they will intersect them at the surface. They also eat wind-blown insects."

And the fish have quite an appetite. "Probably an adult female can eat 500 mosquitoes a day," Miller said.

That sounds like a lot, but mosquitoes multiply at a rapid rate. They can mature from egg to adult in five days at the height of summer and they need very little water to do so.

"Mosquitoes can breed in two or three millimeters of water," Miller said. "So a situation like [a swimming pool] is prime for breeding mosquitoes."

Miller has set up a prime breeding area of his own for the fish whose sole purpose is to control the mosquito population. Since last year he has increased the fish capacity by 210 percent.

"We really need to get on top of these pools right now because they are a potential nightmare," he said.

Miller sends bags of fish -- 150 in each -- with the pool crews sent out to inspect mosquito-infested pools. Jeremy Tamargo does approximately 10-15 of those inspections a day.

"We are definitely getting a lot more due to the housing market and the foreclosures," he said.

Often complaints are called in by neighbors, like Julie Peterson. Her former neighbors' abandoned pool had become an eyesore and a health hazard.

"The house is abandoned. It's probably been empty for a month," she told Tamargo. "The water level is low and it's green."

"It was horrifying, I couldn't believe it," she said of seeing the pool for the first time. "The smell is a bit of a concern, but mostly I was worried about mosquitoes. We spend the whole summer out in our yard and I didn't want everyone to be attacked by mosquitoes."

The last time she saw her neighbors -- who kept the pool in "pristine condition" -- was in March.

"They were there for about a year and a half. They had three or four kids. They used the pool all the time," she said. "They took care of it themselves."

Tamargo inspected the pool before pouring the fish into the water.

"They will be in here indefinitely," he said, "or until someone steps in and buys the house or takes the initiative to clean the pool."

He's trying to get a jump on these pools before the hot weather makes a bad situation even worse.

He says that the worst-case scenario is "a half million maybe even a million [mosquitoes], where the whole water is black and bubbling with activity, but that is normally later on in the summer when it heats up to above 90 degrees."

The county cannot just drain the water because an empty pool can crack and damage the surrounding grounds. Crews are counting on these little fish to do a big job. If only fixing the entire foreclosure mess was as easy as pouring fish into a pool.