Health officials in Miami-Dade County are investigating a possible Zika virus case that is not travel-related, according to the Florida Department of Health, but they did not say if it involves a bite from a native mosquito.
The case could represent the first local transmission of the virus in the United States.
As of Tuesday, all other cases of Zika virus investigated in Florida had been travel-related. The virus, which produces little or no symptoms in many people but can cause severe birth defects when pregnant women are infected, can also be sexually transmitted.
The state health department said it would make Zika prevention kits and repellent available at its Miami-Dade office.
Florida, replete with mosquitoes, has long been considered vulnerable to a Zika outbreak if the virus spread to America. It has struck Brazil especially hard and prompted travel warnings for pregnant women.
In June, Gov. Rick Scott authorized state officials to spend more than $26 million to fight Zika. Days later, Senate Democrats blocked more than $1 billion in federal funding for programs related to the virus.
Earlier in the year, a study found that Tampa Bay was one of nine spots across the country that could see a large population of the kind of mosquitoes that carry Zika this summer.
If the Miami-Dade case turns out to be a confirmed local transmission of Zika, it will make South Florida the "ground zero" for the virus in the continental U.S., said Carlos Fernandes, director of Hillsborough County Mosquito and Aquatic Weed Control.
"It was just a matter of when," Fernandes said. "It wasn't a matter of if."
The Miami and Orlando areas were considered at risk because they are transportation hubs in and out of the country, said Dennis Moore, director of the Pasco County Mosquito Control District. As of Wednesday afternoon, the state health department reported, Miami-Dade had 89 travel-related Zika cases and Orange County had 33.
The two types of mosquito that are known to carry the virus — Aedes aegypti and Aedes albopictus — do not have wide ranges. If some had the virus in Miami, Moore said, they could not make a straight flight to Tampa Bay.
"These mosquitoes only fly a couple hundred yards, less than a quarter mile," he said.
Infected mosquitoes could, however, make the trip on clothing or in luggage, Fernandes said.
"It's only a matter of time before we see a locally transmitted case, even in Tampa Bay," said Beata Casanas, an associate professor in the University of South Florida's Division of Infectious Disease & International Medicine. "But there's no reason to panic because we are ready for it. We know what to do. We are vigilant."
Florida health officials have experience with mosquito-borne illnesses like Dengue Fever and Chikungunya Virus, Casanas said. They were able to contain a Dengue outbreak in Key West in 2009 and 2010, she said, and they will use similar tactics in the event of a flare-up of Zika.
If someone is found to have Zika, Casanas said, doctors ask them to stay inside for three weeks to avoid being bitten by mosquitoes. Local officials also spray within a mile radius of that person's home.
Mosquito control officials vowed to continue ramped up spraying and trapping efforts across Tampa Bay, a prevention process under way since the threat of Zika emerged earlier this year. They said residents should not panic and should heed the call to drain and cover containers in their yards that hold water and serve as mosquito breeding grounds.
As of Wednesday afternoon, there were seven reported travel-related cases of Zika virus in each of Pinellas and Hillsborough counties, according to the state health department. There were another five in Pasco County, and 284 statewide not involving pregnant women. The health department said it had reports of 43 Zika cases in pregnant women in Florida, but only 12 met the Centers for Disease Control and Prevention's case definition for the virus.
Scientists this week have been parsing over an unusual case of the virus in Utah, where an elderly man infected a caregiver, but the two did not have sex, according to The New York Times. Disease specialists were trying to determine how Zika was spread between the two after the man became infected while traveling out of the country.
U.S. Rep. Vern Buchanan, a Sarasota Republican, said the latest Zika news is a "disturbing yet predictable development" that shows why federal funding is necessary to combat the virus.
"We must do everything possible to protect the public and keep the virus from spreading," Buchanan, co-chair of the Florida congressional delegation, said in a statement. "Washington's failure to approve emergency funding was a national disgrace that needs to be corrected as soon as Congress returns from its summer recess."