TBO.com - TBO is Tampa Bay Online

Mosquito-Borne Viruses Pop Up Earlier

ADVERTISEMENT

By MIKE SALINERO

The Tampa Tribune

Published: July 12, 2008

Updated: 07/12/2008 12:13 am

TAMPA - If you need extra motivation to avoid being bitten by mosquitoes this summer, consider this from the Florida Department of Health:

Mosquito-borne viruses, which can make you violently ill or even kill you, are showing up earlier in more Florida counties this summer than last. Eastern equine encephalitis has been detected in horses, wild birds or sentinel chickens in 30 Florida counties so far this year, including Hillsborough and Polk counties. Last year, only 15 counties had seen evidence of the virus during the same period.

Two wild birds in Hillsborough County tested positive for encephalitis in February and a horse was infected in Polk the same month. The disease, though, has not turned up in the sentinel chickens that Hillsborough and other Tampa Bay area counties put outdoors in cages to monitor disease-spreading mosquitoes.

West Nile virus, which usually becomes prevalent later in the summer, has shown up in five counties, the same amount as this time last year.

So far no humans have gotten sick from the viruses, but the situation is serious enough that the Health Department has issued mosquito-borne illness advisories in Jefferson, Volusia, Walton and Washington counties. Last year by this time, no counties were under this heightened alert.

The advisories are based in part on two or more horses being infected within two weeks.

"We have had an increase in activity in horses this year over what we typically see for Eastern equine encephalitis," said Rebecca Shultz, an epidemiologist who coordinates the Health Department's mosquito-borne virus surveillance program. "The last time we had that was in 2005 and we ended up with 150 horse cases and five human cases."

Outbreaks Can Happen Anytime

Local mosquito control agencies are working full throttle now that summer rains have begun. So far, the mosquito season has been fairly typical - annoying but not unbearable - though outbreaks can happen in a neighborhood at any time.

The agencies generally concentrate on killing mosquitoes during their aquatic life-cycles, using helicopters and planes to cover large marshy areas with larvicides.

"Some mosquitoes can fly several miles," said Dennis Moore, director of the Pasco County Mosquito Control District. "So what was contained in a few square miles, all of a sudden it's over 30 square miles and you have to treat a much larger area."

All three counties still use fogger trucks to kill adult species. The trucks are limited in their coverage area and are used mainly in subdivisions where residents have complained and where mosquito traps have shown particularly high infestations.

So far this year, Hillsborough fogger trucks have deployed to Nine Eagles and Waterchase subdivisions in the northwest; South Tampa from Kennedy Boulevard to MacDill Air Force Base; Town 'N Country and upper Tampa Bay; and the Palm River area south of the Selmon Crosstown Expressway.

In addition to alerting authorities to large outbreaks, mosquito traps also identify which species are showing up where. In Pinellas County there are 34 species of mosquitoes, but not all of them are dangerous to humans.

"We try to focus on the mosquitoes capable of transmitting virus," said Nancy Iannotti, director of Pinellas County Mosquito Control. "And then we try to knock down the nuisance species."

Hillsborough County, which spends about $3 million a year on mosquito control, has 70 traps spread over 1,100 square miles.

"I wish we had more than that, but it's very labor-intensive," said Carlos Fernandes, director of Hillsborough mosquito control. "You have to set up the traps, collect the traps and identify the mosquitoes."

Encephalitis usually originates in mosquitoes that live in swamps and feed primarily on birds. The virus spreads when the birds fly out of the swamp and are bitten by other mosquitoes that feed on mammals, including humans. Horses tend to get the virus more often because they stay outside.

A Split On The Issue

The early advent of the viruses doesn't necessarily mean there are more mosquitoes this year. Experts say people might be noticing them more now that the daily storms have returned.

Two longtime Floridians are split on the issue. Bob Minthorn, who lives on the Alafia River, said mosquitoes are "slightly worse" than in past years.

"We're finding one or two in the house and it's been years since we've had mosquitoes in the house," Minthorn said. "And we've noticed when we go out to work in the yard in the mornings, we're going to use spray on our arms and legs."

But George Prance, an avid fisherman from Largo, said the mosquitoes are no peskier this year than in the past.

"I haven't noticed anything different from the last couple of years," Prance said. "That doesn't mean they've been any good the last couple of years."

What Can You Do?

In addition to wearing protective clothing and wearing mosquito repellant, health authorities advise residents to eliminate standing water in their yards. Mosquitoes spend the first stages of their lives in water and can go from egg to adult in as little as four days. Hot weather speeds up the process.

"Trash cans, little children's toys like wagons and kiddy pools, recycling containers and planters: They hold water and breed mosquitoes," said Iannotti, from Pinellas County mosquito control.

Hardware and feed-and-seed stores sell mosquito dunks that can be put in bird baths or ornamental ponds to kill mosquitoes breeding there. The biological agent in the dunks will not sicken or kill birds, fish or wildlife, Iannotti said.

Reporter Mike Salinero can be reached at (813) 259-8303 or msalinero@tampatrib.com.

Share this:

Loading Comments...

Email Print

ADVERTISEMENT