Hillsborough steps up spraying in wake of encephalitis death

TAMPA – The woman who died earlier this month from Eastern equine encephalitis is the first human case of the mosquito-borne disease in Hillsborough County since 1964 and the first death in the U.S. since 2008.

In reaction to the death and positive tests for other diseases such as West Nile Virus, the county increased mosquito control efforts in northwest Hillsborough, where the woman lived, said Donny Hayes, general manager of Hillsborough County Mosquito Control.

Trucks sprayed the area Friday night, and Tuesday morning an aircraft sprayed in an attempt to kill the female mosquitoes that carry the virus.

The county plans another round of aerial spraying in northwest Hillsborough early Thursday morning.

Crews also stepped up daytime spraying of stagnant water where the mosquito larvae live and increased trapping efforts to discover the extent of the mosquito population, Hayes said.

The woman’s death from the rare but highly lethal virus comes amid signs mosquito-borne diseases are possibly more prevalent in Hillsborough County than in the past few years.

Monitoring for disease-carrying mosquitoes in Hillsborough County so far in 2010 has yielded two to three times more positive tests than in the past three or four years. This year, 15 of the sentinel chickens tested positive in Hillsborough for West Nile virus or Eastern equine encephalitis.

Normally at this time of year, five to seven of the chickens caged at different locations to provide an early warning for mosquito-borne illnesses test positive. West Nile virus appears especially prevalent.

“We’re seeing an increase across the board,” said Steve Huard, Hillsborough County Health Department spokesman.

West Nile hasn’t shown up as much in Pinellas. In May, two chickens tested positive, said Maggie Hall, spokeswoman for the Pinellas County Health Department.

The Hillsborough health department won’t identify the woman who died July 1 but tests confirmed Friday that she died from Eastern equine encephalitis, Huard said.

Mosquitoes spread the disease by biting infected birds, then biting people. Horses also can contract the virus but it cannot spread from horses to people, from person to person or human to horse.

Though rare, the virus can cause a swelling of the brain. About one-third of the people infected die. Another one-third survives but with serious neurological effects, said Danielle Stanek, medical epidemiologist with the Florida Department of Health. The rest recover.

There is no treatment for the virus and no vaccine for humans. A vaccine is available for horses.

Florida usually sees up to three human cases a year. Some years, such as 2009, have none, Stanek said.

Since 1955, 74 people in Florida have contracted Eastern equine encephalitis.

Once health officials investigate the woman’s death, they will probably find she had more exposure to mosquito bites than most people, said Jonathan Day, a University of Florida medical entomologist.

“It is a numbers game. The more you’re bitten, the more chance you have of getting it,” Day said.

Equine encephalitis generally is considered a rural disease, partly because the mosquito that spreads the virus from bird to bird lives in marshes and swamps, Day said. That mosquito does not bite humans.

Other mosquitoes spread the disease to people after biting an infected bird. One, Culex nigripalpus, is everywhere during the wet summer months.

“You’ll find it from downtown Tampa to rural areas,” Day said.

It primarily feeds from dusk until about three hours after sundown and also carries West Nile virus.

Another mosquito vector for the virus breeds in ponds that have aquatic vegetation, Hayes said.

That insect, Coquillettida perturbans, feeds day and night and is an aggressive biter, he said.

Via: http://www2.tbo.com/content/2010/jul/20/211604/1st-fatal-equine-encephalitis-case-2008-confirmed/news-breaking/

Mosquito Control


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