Florida is one of several U.S. states now reporting a few isolated cases of people infected with the Zika virus. In response, Florida's Gov. Rick Scott has declared a public health emergency in five counties in hopes of getting ahead of the virus's spread.
So far, just 12 cases of the mosquito-borne illness have been reported to health authorities in Florida, all of them among travelers who contracted the disease outside the U.S. But Scott figures it's only a matter of time before the virus starts showing up among mosquitoes in some regions of the state, too.
"We have to ensure that Florida's safe," he says. "Just like in a hurricane, we always say to ourselves, 'We'll prepare for the worst and hope for the best.' And we're going to do everything we can to stay ahead of the Zika virus."
Scott is calling for stepped-up monitoring, urging that special attention be paid to mosquito control in Miami-Dade and four other counties where Zika cases have been reported. He's also asked the Centers for Disease Control and Prevention to provide Florida with at least 1,000 antibody test kits so it can check people who traveled abroad and had symptoms of Zika — especially pregnant women.
So far, Florida's Zika cases have been restricted to people who recently returned from travel to Haiti, Venezuela, Colombia or El Salvador.
With its mild climate, Florida is susceptible to mosquito-borne diseases. Over the years, the state has experienced sporadic outbreaks of dengue and chikungunya — other tropical diseases carried by the Aedes aegypti mosquito, which is prevalent in Florida.
"I would like to bet money on the fact that we will see locally-acquired cases," says Dr. Amy Vittor, an internist and public health researcher who studies tropical diseases at the University of Florida. Still, the state is unlikely to see the scale of the Zika outbreaks now sweeping through the Caribbean and Latin America, she and other health officials say, in part because residents of the Sunshine State have far less exposure to mosquitoes.
"We get in from our air-conditioned house into our air-conditioned car in the garage and drive to our air-conditioned office and then right back home," Vittor says. Contrast that, she says, to someone who lives in a dense urban setting, without air-conditioning or window screens, waste management or water sanitation.
"They have a very different exposure risk," Vittor says.
Only about 1 in 5 people infected with Zika become ill, according to the CDC. And, as tropical diseases go, the symptoms are usually mild: a fever, rash, headaches and joint pain. But because the virus has been correlated with a rise in microcephaly and other birth defects in other countries, Zika is especially worrisome. Those concerns may have played a role in Gov. Scott's decision to declare a public health emergency.
That wasn't done in 2009 and 2010 when Key West had nearly 90 cases of dengue fever, which can be lethal if it isn't promptly recognized and treated.
Key West, the southernmost city in the continental U.S., is a small, densely-populated place in the subtropics. "We are the perfect climate for A. aegypti mosquitoes — and any mosquitoes," explains Beth Ranson, who represents the Florida Keys Mosquito Control District. "We are hot and we are humid."
Ranson says, so far, her agency isn't doing anything special to prepare for Zika. But day-to-day mosquito control in the Keys is already pretty intense, with a fleet of planes and helicopters and a couple dozen inspectors ferreting out the places mosquitoes breed.
Even with its aggressive mosquito control effort, the Keys Mosquito Control District has only been able to cut its population of Aedes aegypti mosquitoes in half.
Ranson says that's why the district is looking at deploying genetically-modified mosquitoes. A British company, Oxitec, has developed genetically-modified A. aegypti mosquitoes that produce offspring that don't live to adulthood. In experimental trials in Brazil and other countries, Oxitec has shown it can reduce the A. aegypti population by 90 percent, says Derric Nimmo, a product development manager at the company.
"Now, of course, Zika has gained prominence in the past few months with this link to microcephaly," Nimmo says, "so there has been a much greater impetus in Brazil to look at how they can control this mosquito."
Oxitec is still waiting for the FDA to approve a trial release of the GMO mosquitoes in the Florida Keys. One obstacle has been a vocal group of opponents.
A local businesswoman in the Florida Keys, Mila de Mier, gathered more than 100,000 signatures a few years ago on a petition opposing the trials, which she hand-delivered to the FDA offices in Washington. She's worried about the risk of introducing genetically modified mosquitoes into the environment, she says, especially when there is no imminent risk of disease.
"We don't have dengue. We don't have chikungunya. We have no Zika," de Mier says. "And we are concerned. The Mosquito Control (district) is doing a really good job here. We don't see the need to jump into this."
But Ranson says the idea is to head off dengue, chikungunya and Zika outbreaks before they occur.
"Waiting until it's here before we have the ability to get the tools is not smart," Ranson says. Though it's been nearly six years, she notes, since her district and Oxitec began working toward conducting an experimental trial of the GMO mosquitoes in the Keys, approval to begin the test is still uncertain.
Other mosquito control districts in Florida have expressed interest in trying the GMO mosquitoes once the Keys trials are approved, Nimmo says. Meanwhile, Oxitec is expanding such tests in Brazil and hopes soon to receive permission there to begin marketing its GMO mosquitoes commercially.