PINELLAS COUNTY, FL — Three chickens in one of the Pinellas County Mosquito Control Department's sentinel chicken flocks have tested positive for West Nile virus.
Florida Department of Health-Pinellas County public information officer Tom Iovino issued an advisory Thursday afternoon, alerting the public of the presence of the virus in the chickens' blood samples.
The Mosquito Control Department maintains eight sentinel chicken coops throughout the county and draws blood from the chickens once a week. The FDOH tests the blood for antibodies to viruses that are easily passed from mosquitoes to birds and vice versa, such as eastern equine encephalitis, St. Louis encephalitis and West Nile viruses.
The mosquitoes that transmit these viruses are partial to blood from birds so Pinellas County's sentinel chickens serve as an early warning of the presence of these potentially serious viruses that can be passed on to humans, horses, dogs and other animals.
Chickens serve as ideal sentinels to alert health officials of the presence of these viruses because, while they can be infected with these viruses and produce the antibodies, they don't experience the illness and are unable to transmit the viruses to uninfected mosquitoes.
Iovino said the fact that three chickens in a single flock tested positive for the West Nile virus raises the chances that the virus can be spread to humans in Pinellas County.
"The chickens serve as an early warning for the presence of the virus," he said. "We use this information to target mosquito species of concern in areas that have circulating virus."
West Nile virus can cause mild to severe illness, according to the FDOH.
It was first identified in Uganda in 1937 and showed up in the United States in 1999 in New York, reaching Florida in 2001.
Since its initial detection, human cases of West Nile virus have been reported in all U.S. states except Alaska and Hawaii. The virus is now considered endemic in the U.S., with annual epidemics occurring in some parts of the country, peaking in the late summer months.
As of Aug. 8 this year, the virus was detected in Miami-Dade County June 7, July 18 and July 29; in Osceola County June 7; and in Sarasota County on Aug. 5.
Most West Nile virus infections (approximately 80 percent) are asymptomatic. People who do develop symptoms usually experience a mild illness called West Nile fever that includes headaches, fevers, pain and fatigue.
Less than 1 percent of infected people develop the most severe form of disease, neuroinvasive WNV, which may cause meningitis and encephalitis and can result in irreversible neurological damage, paralysis, coma or death.
People over the age of 60 and those with weakened immune systems (especially transplant recipients and HIV-infected people) are at an increased risk.
There is no specific treatment for West Nile virus, and most mild infections typically dissipate with little or no medical intervention within a few weeks.
Iovino said the health department will closely monitor the sentinel chickens, but reminds residents to take precautions to protect themselves from mosquito-borne diseases by taking the following actions:
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