Two Die in Florida From Eastern Equine Encephalitis

TAMPA, Fla. (Reuters) Jul 30 - Two Florida residents have died from Eastern equine encephalitis, a mosquito-borne disease that is rare among humans but has infected a rising number of horses in the state, health officials said on Friday.

Both deaths were in the Tampa area, where a woman died on July 1 and an infant died on Wednesday, the Hillsborough County Health Department said. There is no vaccine for humans.

"It's a fairly rare disease," said Steve Huard, spokesman for the Hillsborough health department.

Only a few human cases a year are reported in the United States, mostly in Atlantic and Gulf coast areas, according to the U.S. Centers for Disease Control and Prevention. But the disease kills 33% of its victims and survivors often have significant brain damage, the CDC said.

Hillsborough County has issued a mosquito-borne illness alert and sent a plane to spray pesticides to kill mosquitoes that breed in standing water, Huard said.

Eastern equine encephalitis outbreaks are not uncommon among horses in Florida during the wet summer months when mosquitoes proliferate.

Sixty cases have been reported among Florida horses this summer in several dozen counties, Florida Agriculture and Consumer Services Commissioner Charles Bronson said.

Two cases of West Nile disease, another mosquito-borne viral disease, have also been reported among horses in Florida, though the CDC said the state has reported no human cases.

West Nile disease is usually mild in humans and most who contract it have no symptoms, although it killed 32 people in the United States last year.

Mosquitoes carry the viruses that cause both diseases and can transmit them to both horses and humans, but horses do not transmit the viruses to people.

Bronson urged horse owners to get their animals vaccinated against both.

"In the vast majority of cases we have seen this year, the horses either had no vaccinations at all or they were not current," Bronson said.

"We are seeing increases in mosquito populations and, since mosquitoes are the carriers of both these diseases, it's likely the situation is going to get worse before it gets better."

Eastern Equine Encephalitis kills 90% of infected horses, while West Nile virus has a mortality rate in horses of about 30%. Signs of the viruses include fever, listlessness, stumbling, circling and coma.

While the incidence of both diseases is down from levels seen earlier in the decade, the toll for 2010 continues to rise among horses, Bronson said.

Florida has also seen a resurgence of dengue fever, another viral disease transmitted by mosquitoes, in southern Florida after a 75-year absence from the state.

Dengue is common in Central America and the Caribbean and the hemorrhagic form of the disease can kill humans, although no recent dengue deaths have been reported in the continental United States.

Health officials urged residents to use mosquito repellents, wear protective clothing and avoid being outside at dawn and dusk, when mosquitoes are most active.