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Mosquitoes carrying dengue fever can live indoors

When a Palm Beach County family was plagued by a swarm of little black mosquitoes, county mosquito chief Ed Bradford knew to look for Aedes aegypti hiding in the house.

"They were in the Waterpik," Bradford said. "The family hadn't used it in a while, I guess, and there was a little water left in it."

A Broward County family had Aedes in their bottled water system. Another had them in the overflow tray under a refrigerator water dispenser, said Broward mosquito biologist Evaristo Miqueli.

Clogged roof gutters. Little-used toilets. Pet dishes. Recycling bins. Waste tires. Plant pots. Abandoned toys. Foam coffee cups. Stalks of bromeliad plants. Boat covers.

Drain them, flush them or get rid of them.

Anywhere a few ounces of water can collect and stagnate in or outside the house can become the breeding ground for Aedes aegypti, a strain of mosquito carrying the tropical virus dengue fever now present in Key West.

At least 46 people since September have fallen ill from the virus they contracted in Key West, including a Broward County woman. It's the first extended outbreak of the potentially fatal disease in the continental U.S. since 1946. So far the cases are mild, resembling a bad flu.

Health officials across South Florida this week stepped up efforts to track Aedes populations – mostly along the coast at the moment – and to educate people about avoiding mosquito bites.

They warned against worrying too much. Mosquitoes are few due to the dry weather. None outside Key West have been found carrying dengue fever, and almost all people there bitten by infected mosquitoes fought off the virus without getting ill. The virus spreads only by mosquito bites, not human contact.

"There's no virus right now in Broward," said Joseph Marhefka, the county mosquito control director. "We're just doing this as a preventative."

But the more tourists who get bitten in Key West, the greater the chance dengue fever will spread to other areas. And, dengue is often more severe the second time a person gets infected.

Most types of mosquitoes appear after heavy rains and bite at night. Basic steps thwart them: Apply repellent that contains DEET, stay indoors from dusk to dawn, wear long sleeves and pants at night, dump standing water and fix holes in your screens.

Those work fine for the common mosquitoes in South Florida: Culex that carries West Nile virus and St. Louis encephalitis, Anopheles that carries the malaria parasite and some viruses, and Psorophora that carries West Nile and other diseases.

Then there's dengue carrier Aedes. They bite during the day, so good luck relying on long pants and sleeves. Since they live in or near the house, you'd have to wear repellent all day to beat them. Their proximity to humans makes it harder for county fogging crews to reach them.

What's more, when it's dry, Aedes can bloom because people run sprinklers more often and create puddles in yard containers.

"Some of the protections don't work against Aedes," Bradford said.

The best thing you can do is scrutinize your environment and be vigilant about standing water.

Unlike other mosquitoes that can fly 50 miles, Aedes rarely travels more than 300 feet from where it emerges.

"All they need is a little water," Miqueli said. "We need to educate the citizens to look around their own environment and take care of their own situation."

Bob LaMendola can be reached at blamendola@sunsentinel.com or 954-356-4526.

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