County increasing mosquito control efforts

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 has increased mosquito control efforts in northwest Hillsborough, where the woman lived, said Donny Hayes, general manager of Hillsborough County Mosquito Control.

Workers sprayed the area Friday night by truck and Tuesday morning by plane in an attempt to kill the female mosquitoes that carry the virus. The county plans another round of aerial spraying in northwest Hillsborough early this 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 troubling signs that mosquito-borne diseases might be 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 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. 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.