WHAT’S THE DEAL WITH ZIKA, AND IS IT A THREAT TO YOU?

Illustration by Elizabeth Garcia.

For nearly 70 years, the Western world lay peacefully unaware of Zika. After its discovery in 1947, the virus, which is channeled by Aedes mosquitoes, stuck mainly to small stretches of land close to the equator in Africa and Asia. At the time, it seemed to target more monkeys than humans. Research suggests anyone who did contract Zika virus went undiagnosed.

Suddenly, the number of reported cases of Zika in humans exploded. In 2007, an outbreak of the virus infected nearly three-quarters of Micronesia’s Yap Island population. Even then, the disease was mistaken for other mosquito-borne diseases like dengue and chikungunya, wrote Dr. Jorge Rey, interim director for the University of Florida’s Florida Medical Entomology Laboratory, in an online FAQ page. Researchers aren’t sure exactly where or when Zika first cropped up in the Americas, but a study published late last summer indicates the virus likely entered Brazil sometime between August 2013 and August 2014.

Only a few years later, the Center for Disease Center and Prevention estimates that over 3,000 cases of Zika virus have been reported in the continental United States, along with over 21,000 cases in Puerto Rico. Florida stands as the only U.S. state with cases of local transmission, meaning some infections — approximately 169 in total at the time of writing — were carried between humans and mosquitoes at home rather than abroad.

Their origin? Two areas of Miami-Dade County identified by the Florida Health Department that together measure just a few square miles, the sole locations of active local circulation in the U.S. However, the state’s “small case cluster is not considered widespread transmission,” according to the department’s website. In Alachua County, 10 cases of Zika have been reported since February, but all were travel-related. Effectively, “there are no areas of concern” in Alachua County,  wrote Mara Gambineri, Florida Department of Health Communications Director, in an email.

Each time a Florida county confirms its first case of the virus, it is added to an ongoing Declaration of Public Health Emergency for Zika. On Feb. 12, Alachua County made the list. Ten countywide cases of Zika have been reported since then, but all were travel-related, Gambineri wrote.

As cases are continuously confirmed, local health departments and mosquito control districts collaborate in systematically spraying insecticides, destroying breeding sites and educating the public on Zika, Gambineri wrote.

While the health department works to eliminate risk, UF biostatistics professor Dr. Ira Longini, a co-author of the study on the spread of Zika virus cited earlier, is currently working with his colleagues on mathematical models of transmission in the Americas. In a recent study, Longini and his colleagues concluded that the projected numbers of Zika cases in the continental U.S are generally low, with Florida’s clusters of cases representing an outlier.

As for Gainesville specifically, “we don’t have much to worry about,” Longini said. Our own localized cluster of cases is certainly possible, but unlike tightly packed Miami, Gainesville’s low population density grants the majority of the city room to breathe easy. Besides, it is the infected people, not the mosquitoes themselves, that pose a legitimate threat of spreading the virus beyond their neighborhoods. “The average Aedes mosquito is born, lives, works and dies within 100 meters,” Longini said.

The two species of Aedes mosquitoes that can transmit the virus, Aedes aegypti and Aedes albopictus, propagate throughout Florida, but not in large bodies of water. Both species are considered “container mosquitoes,” meaning all they need is a bottle cap’s worth of water to multiply, said UF entomologist Roxanne Connelly in a Zika webinar.

As soon as the water level in a container rises, mosquito eggs hatch and continue to live as larvae and pupae aquatically, leaving an opportunity for vigilant humans to shut down their development. Bromeliad plants, old tires, flower pot saucers, rooftop gutters and bamboo sticks can all easily house the larvae, so weekly inspections of yards, porches, or gardens to search for objects that need draining are key to cutting down their stock.

Should your precautions fail, you may not even know you’re infected. Only about one in five people exposed to the virus show any indication of the disease, Rey wrote. The symptoms outlined by the CDC are fairly tame — fever, rashes, headaches, reddened eyes and joint and/or muscle pain — and could easily be confused with a cold or a bad hangover. Those infected only have the potential to pass on the virus to mosquitoes for about a week, Longini said. After that period of time, the condition effectively resolves itself, and hospitalization is rarely needed, Connelly said.

“The point of the study is that we don’t really know necessarily how long people are infectious for — and that’s a very broad term to say, infectious,” Iovine said.

So why is Zika so scary? The predominant concern about the virus is its effect on unborn babies. The CDC said infection during pregnancy can cause birth defects like microcephaly, a condition where a baby’s head is too small and its brain often underdeveloped. “There also are babies born without microcephaly, but they have other neurologic problems,” explained UF-based infectious disease specialist Dr. Nicole Iovine. A correlation between Zika and Guillain-Barré syndrome, a disease in which the immune system attacks itself and results in muscle weakness and even paralysis, is also under investigation. Women who are not pregnant at the time of infection likely don’t need to worry about future birth defects.

Further complicating the situation is Zika’s ability to be sexually transmitted, a factor not considered by the model in Longini’s projections. Zika is a blood-borne virus, but it has been detected in a range of bodily fluids, including semen, vaginal secretions and saliva. Semen in particular has been observed in some studies to maintain viable Zika virus for over 60 days after its initial infection, the CDC wrote. The amount of time someone remains viable to sexually transmit Zika is yet to be determined.

Iovine is working to combat that unknown. By studying symptomatic patients’ body fluids, she and her colleagues hope to discern how long the virus persists in them.

“The point of the study is that we don’t really know necessarily how long people are infectious for — and that’s a very broad term to say, infectious,” Iovine said.

There are still several unanswered questions about Zika, like the frequency of sexual transmission, whether the trimester during which an infection occurs influences the severity of subsequent birth defects, or if all infants born to a parent infected with Zika during pregnancy will be affected. Another question lies in the viral load of mosquitoes, or if “one mean mosquito is enough,” Iovine said.

“The thing that we do know is that if you can protect yourself from mosquito bites, and if you use barrier methods of contraception, your chances of getting Zika are low,” Iovine said. And when it comes to protecting against mosquitoes, experts recommend long-sleeved clothing and pants. In the Florida heat, repellents might be more practical.

Chances are, unless you’re traveling abroad, a frequent visitor to Miami, pregnant, or planning to become pregnant, you don’t need to worry too much about Zika. At least in Gainesville’s own bubble, precautions must be taken, but it’s not time for panic just yet.