TAMPA — A Brandon-area infant has died from a rare and devastating disease transmitted by mosquitoes that causes inflammation of the brain, health officials said Thursday. It was the second death in Hillsborough County this month from eastern equine encephalitis, prompting officials to issue a public health alert and step up mosquito spraying around the Tampa Bay area.
Since no more than five to 10 cases of EEE are typically reported nationwide each year, and Florida's last reported death was in 2008, these back-to-back fatalities are highly unusual.
And the state recorded a third EEE fatality this month, in the Panhandle's Wakulla County.
There is no vaccine for the disease, which kills about one-third of those infected and disables others, so officials are urging people to protect themselves from mosquito bites (see box, right).
This summer could be the worst in years for the spread of mosquito-borne illnesses. Dengue fever, which is far less deadly than EEE, has been circulating in Key West for the past year, the first outbreak in Florida since the 1930s. Health officials say a Pinellas man who was visiting the Keys was among those affected, but he has recovered.
Yet another mosquito-borne illness, West Nile virus, could become a threat in Hillsborough and many parts of the state later this summer, officials say, to judge by environmental conditions and animal surveillance systems.
There aren't more mosquitoes here than usual, officials say, but more of them are carrying diseases, posing greater health risks to the people they bite. Due to factors such as water levels and animal breeding patterns, mosquito-borne illnesses tend to rise and fall over time.
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After several quiet years, health experts are concerned that people have forgotten that these insects are not just a backyard nuisance. While mosquito-borne disease is generally rare in the United States, mosquitoes are the world's most dangerous animal, responsible for millions of cases of malaria worldwide.
In response to the increased threats, Hillsborough's health department on Thursday placed the county under a "mosquito-borne illness alert."
"You have to protect yourself," said Warren McDougle, manager of the Hillsborough Health Department's epidemiology program. "Every effort is being taken by mosquito control and all of the public health entities to do the surveillance on the disease, but individuals have to protect themselves against mosquitoes."
It takes just a bite to get sick, he noted, though your chances of getting sick increase the more you are bitten.
Last week, officials reported that a woman who lived in northern Hillsborough died on July 1 from an EEE infection. She likely was infected while sitting outside her apartment building, officials say.
The Brandon-area infant's cause of death was reported to the health department Wednesday; officials declined to share more information about the victims.
People who spend a lot of time outdoors are at greater risk for EEE because they are exposed to more mosquitoes. The virus is transmitted to horses and humans by mosquitoes, which pick it up from birds.
People can't infect each other, nor can they be infected by horses, which is where the virus was first detected. Because the disease is so rare in people, experts look to equine cases to help monitor the risk. The Pasco County Health Department, for example, reported on Thursday that county's second case this summer of EEE in a horse.
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Yet people living far away from these reports are not immune, experts caution, since birds can spread the virus some distance. The disease is reported in many Atlantic and Gulf Coast states, though hot, wet Florida is the most affected.
"Anywhere where you are in the state, right now this year, you do need to be concerned about it," said Roxanne Connelly, a University of Florida associate professor at the Florida Medical Entomology Laboratory.
She noted that EEE is the most serious of the mosquito-borne illnesses seen in Florida. It can cause flulike symptoms that begin four to 10 days after the bite of an infected mosquito.
The disease can progress to disorientation, seizures and coma. The fatality rate is high, and many of those who survive are brain damaged. In the last decade, most of the deaths in Florida have involved young people.
There is no treatment specifically for an EEE infection. Horses can be immunized against the virus, but there isn't a vaccine to protect people.
Last week, Hillsborough County sprayed extensively by air in the suburbs north of Waters Avenue and west of Bruce B. Downs Boulevard. This morning, they plan to spray again around Brandon, covering communities from Seffner to Valrico.
"We are taking all the actions that we are supposed to, but the population also needs to be aware and help us out," said Carlos Fernandes, director of mosquito control in Hillsborough. He urged people to stay inside at dusk and dawn when mosquitoes are most active.
Pinellas also plans to dispatch trucks early today to fog along the Hillsborough and Pasco county lines.
Nancy Iannotti, operations manager for Pinellas mosquito control, said the mosquito-borne diseases are rare, but sensible precautions still should be taken. "Even if you're driving to 7-Eleven, you want to put your seatbelt on. You want to protect yourself."
Times researcher Carolyn Edds and staff writer Jared Leone contributed to this report. Letitia Stein can be reached at firstname.lastname@example.org or (813) 226-3322. For more health news, visit www.tampabay.com/health.