State: West Nile's arrival in Keys confounds health officials

After covering most of North Florida and dipping into Pasco County, the West Nile virus has suddenly been found in the Florida Keys, where it is blamed for sickening a vacationing Sarasota woman.

The woman, who is 73, recovered after seven days in a South Florida hospital. Now state health and wildlife officials are trying to figure out how the virus apparently skipped much of Central and South Florida before finding the state's southernmost county.

West Nile, like St. Louis and eastern equine encephalitis, is carried by birds and spread to other birds, humans and horses by mosquitoes. Scientists following it had expected it to march southward this summer, at least until the fall bird migration began.

"I was frankly quite surprised to see that one pop up so far south," said Tim Breault, assistant director, division of wildlife, of the Florida Fish and Wildlife Conservation Commission.

"It's going to probably be several years before wildlife biologists and ornithologists understand who's got it and whose actually moving it. Right now it's a shot in the dark. You can pick up the dead ones."

State health officials have been tracking the West Nile virus by following reports of dead birds around the state, then testing them for the virus. Hundreds have been tested, and the disease has been found in birds across North Florida.

Except for one bird that tested positive in Pasco, the virus was not believed to be south of Ocala until the Sarasota woman contracted it in Marathon, in the Keys. Monroe County was added Friday to the list of 34 counties under a state medical alert for West Nile and eastern equine encephalitis.

Dr. Steven Wiersma, acting chief of the bureau of epidemiology for the state Department of Health, said officials determined the woman was infected there, rather than at home, by counting the days: West Nile has an incubation period of five to 15 days, and she felt the first symptom, a stiff neck, in late July.

She was in the Keys at the time, and had been there for at least 18 days.

The woman became the fourth person in Florida, and the first outside of North Florida, to contract the exotic disease. She recovered after seven days in a South Florida hospital and was sent home Aug. 12, but tests showing she had the disease were not completed until this week, health officials said.

State and county health departments would not release her name, and she declined an interview request through Sarasota County officials.

There are several possible explanations for the virus' sudden appearance in Monroe, experts say. An infected bird or flock of birds could have headed south early, arriving in the Keys this summer, or the disease could have hopscotched south by infecting bird after bird throughout South and Central Florida.

Or, as Tim Regan finds more likely, the virus made it to the Keys last fall, with the southward migration, but simply wasn't detected.

Each fall, Monroe boasts the highest concentration of migratory birds in the eastern United States, so it's not unlikely that a bird from up north with West Nile stopped there.

"Chances are, it was here last winter, and it just never manifested itself and nobody caught it, either humans or horses," said Regan, biologist for the Fish and Wildlife Commission's regional office in West Palm Beach, which covers the Keys.

Until Friday, when calls began pouring in, Monroe County residents had reported just three dead birds to state surveillance officials. None of of the birds tested positive. Wiersma said that's not nearly enough to detect West Nile.

"You probably had a lot of people saying this isn't a Keys problem, this is a North Florida problem, and they (weren't) reporting it," he said. "I think now that things are heating up down there, in terms of the media interest and the public interest, we probably will get a lot of reports of dead birds, and we probably will find the virus.

"Ideally we would have gotten those reports first, so we could warn everybody."

Likewise, state health officials are pretty sure West Nile is not widespread in Central or Western Florida because hundreds of dead birds have been reported and tested, and only one in Pasco has tested positive.

More have been sent from Pinellas County than almost anywhere else, he said. If the virus were there, he says, it would have been detected. Dead crows and blue jays seem to be the best indicators the virus is nearby.

But, Wiersma added, "There's nothing that's going to stop it. It's going to be all through Florida soon, we just don't know how soon. I really don't believe it's in a lot of places in Florida, but it will be."

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Lucy Morgan

From the Times state desk