ST. PETERSBURG — Mosquito-borne St. Louis encephalitis may have made its way to the area for the first time in six years, Pinellas County officials said Wednesday.
That means West Nile virus may not be the only illness residents have to worry about this mosquito season.
West Nile virus already was found in chickens in Pinellas, Hillsborough and Hernando counties.
Last week, officials thought they had a second case of West Nile in Pinellas, but tests showed that wasn't the case. Instead, experts began to suspect they found St. Louis encephalitis, which many thought had been wiped out of Pinellas in 2005.
St. Louis encephalitis, or SLE, is native to Florida and attacks the central nervous system. In very rare cases, it can be fatal, the Pinellas Health Department said.
Before an outbreak of West Nile in 2005, SLE was the county's primary foe, said Nancy Iannotti, director of Pinellas Mosquito Control. "West Nile came to Florida with a vengeance, and completely wiped out the native species," Iannotti said. "If this turns out to be SLE, we would still have West Nile, but it might be more a returning to normal."
Iannotti said a definitive test will be completed by early next week.
Current conditions — a long dry season followed by recent concentrated rains — are perfect for the disease to spread, said Andrea Castillo, the Health Department's infectious disease surveillance manager.
Mosquito-borne viruses are passed from birds to bugs and vice versa, Iannotti said. When the two species frequent the same water-sources, disease spreads more quickly.
That's why the county isn't waiting to act, Castillo said.
Spray technicians are hitting target areas for mosquito breeding. The county on Wednesday launched aerial spraying over the Sawgrass Lake Park area, where sentinel chickens are kept, in addition to fogging that began Tuesday.
If a person were to contract SLE from a mosquito bite, Castillo said, it could take up to 15 days before symptoms show. "Most people who get infected have no symptoms or only mild flulike symptoms," she said.
The last recorded Florida death from SLE was in the Panhandle in 2002, officials said.
Experts advised residents to use mosquito repellent with DEET, wear loose-fitting clothes while outside for long periods of time, avoid outdoor activities at dusk and dawn and get rid of standing water where mosquitoes can breed around their homes.