West Nile virus has been found in five Pinellas County chickens, meaning mosquitoes carrying the virus are in Pinellas and could transmit it to people.
But no human has ever been diagnosed with West Nile in Pinellas County, health department officials say. They urge people not to panic, but to take precautions.
Precautions include avoiding outdoors between dusk and dawn and using insect repellents containing DEET.
Eight flocks of chickens are placed around the county to monitor for West Nile and other diseases.
This is the largest number of chickens to test positive this year for West Nile, said Julia Gill, epidemiology program manager for the Pinellas County Health Department. But a few other chickens have tested positive this year, and several did last year, without human cases of the virus being diagnosed.
About 20 percent of people infected with West Nile will develop symptoms, such as headache, fever and body aches. About one in 150 people will develop a more serious illness, according to the Centers for Disease Control. In those people, the disease can lead to permanent neurological damage, coma or death.
Florida has had relatively few cases of the disease, with 66 cases and no deaths reported this year. Nationally, there have been 3,541 cases and 66 deaths reported this year.