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Pesky mosquitoes will only get worse with summer's rains

Mosquito Control technician Leanne Lake treats a tidal overflow area in Tarpon Springs to help stop salt marsh mosquitoes.

DOUGLAS R. CLIFFORD | Times

Mosquito Control technician Leanne Lake treats a tidal overflow area in Tarpon Springs to help stop salt marsh mosquitoes.

Lynne Lacroix couldn't leave her home without being eaten alive.

The rainy season hadn't even started, yet the 62-year-old found herself churning through cans of mosquito repellent, mindful of the blood-sucking creatures lurking just 500 feet away on a Tarpon Springs beach.

"I generally can keep them off me by spraying," she said. "But that's costly."

Tampa Bay area mosquito control officials have been inundated in recent weeks with mosquito-related complaints like Lacroix's — and that was before the rains came this weekend.

They attributed the spike to a proliferation of salt marsh mosquitoes

"They're horrible biters," said Nancy Iannotti, operations manager at Pinellas County Mosquito Control. "Coastlines are prime locations for homes. When they come off, they're in such huge numbers and they're such bad biters. And they can be out in any time of the day, while others generally will be out only at night."

Meanwhile, Iannotti said the domestic mosquito — commonly known as the "ankle biter" — has weathered the dry conditions by relying on leftover water in clogged roof gutters and in unattended pools behind foreclosed homes, among other places.

Now that the rains have come, experts warn it could get worse as more common mosquitoes, like those of the woodland and floodwater varieties, start to breed in puddles and ditches.

With them come heightened concerns about mosquito-borne illnesses like West Nile virus and eastern equine encephalitis, diseases that have arisen in the Tampa Bay area in the past.

A brief lifespan of about three weeks renders salt marsh mosquitoes largely incapable of spreading disease because, in that short time, diseases lack ample time to incubate.

When it was dry, experts worried because mosquitoes and birds — their primary sources of nourishment and hosts of disease — were likely to congregate around the same few water holes, creating a concentration that has proven to increase the likelihood of disease transmission.

"The possibility for them to be at the same waterhole is much higher," said Dr. Carlos Fernandes, director of the Hillsborough County Mosquito Control. "Sometimes the population goes down but the level of disease, the level of contamination of mosquitoes, tends to go up.

Now that it's wet, birds and mosquitoes disperse to a better selection of water sources — but that brings its own concerns.

"They were very congregated and now they're spreading out," Iannotti said. "That's not necessarily to say we're going to get a virus. But those are the conditions in which it could happen."

Even with heavy rainfall, Iannotti said the dry weather might still have stymied mosquito reproduction. Many larvae, she said, might have been flushed away or pummeled into the earth.

Before the weekend rain, University of Florida medical entomologist Jonathan Day said the Tampa Bay area was especially at risk of becoming a mosquito breeding ground with wetter weather. Heavy spring rains, he said, had raised the water table to a point where it could swell up and form pools for larvae, perfect for the eggs floodwater mosquitoes instinctively know to lay in dry ditches.

As of last week, Hernando County's number of trapped mosquitoes had already topped last year's total. Since April, traps have caught 7,294 mosquitoes — almost 2,000 more than the total from April through June of last year.

From February through May, Fernandes said, Hillsborough County Mosquito Control collected a monthly average of about 60,000 mosquitoes — almost twice that of the same span last year. That average coincided with about 100 service requests per day, he said. But with the dry weather earlier this month, the daily average for service requests sank to between 30 and 50 a day.

He said mosquitoes from the genus culex, a type similar to saltmarsh and domestic breeds, have proven surprisingly prevalent this month. They've been known to carry West Nile virus, St. Louis encephalitis and heartworm, he said.

In July 2005, a 27-year-old man became the first West Nile virus case in Pinellas County. The number of cases reached double digits in an outbreak officials suspect was influenced by the dry weather. Later that summer, an 18-month-old Land O'Lakes girl died of eastern equine encephalitis, a disease that reappeared this month in a chicken held at a Hernando testing facility.

Hernando's Mosquito Control has stepped up its spraying since the state-issued report revealed the virus' presence, said its director, Dr. Guangye Hu.

Otherwise, Hu and his counterparts said they will spray as needed, paying close attention to the number of mosquitoes collected in traps — and the number of service requests.

C. Ryan Barber can be reached at rbarber@sptimes.com or (727) 893-8505. Follow him on Twitter at twitter.com/cryanbarber

How to keep mosquitoes at bay

Don't let pesky mosquitoes ruin your summer:

. DRAIN

remove standing water
from any receptacle.

. Empty and clean

bird baths and pet water bowls once or twice a week.

. Protect

boats and vehicles
with tarps so they
don't accumulate water.

. Maintain

the water balance (pool chemistry) of swimming pools. Empty plastic swimming pools when not in use.

. Cover up

if you must be outside
when mosquitoes are active. Wear shoes, socks, long pants, and long sleeves.

. Apply

mosquito repellent
to bare skin and clothing. Repellents with DEET, picaridin, oil of lemon eucalyptus, and IR3535
are effective. Use mosquito netting to protect children younger than 2 months.

Florida Department of Health, Bureau of Environmental Public Health Medicine

Pesky mosquitoes will only get worse with summer's rains 06/25/11 [Last modified: Tuesday, June 28, 2011 12:47pm]

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