Miami-Dade County reported ten new cases of locally transmitted Zika on Monday, bringing the total number of native U.S. cases to 14. In the wake of the outbreak (which is so far limited to a small area just north of downtown Miami), cities around the country are preparing for their own outbreaks of the mosquito-borne disease that has been linked to microcephaly and other birth defects in Latin America and the Caribbean.
From New York to Los Angeles, urban areas are in danger of outbreaks this summer because of the proliferation of the Aedes aegypti mosquitoes which carry the virus.
But in few cities has the debate about possible solutions grown so heated as in Key West, a community of 25,000 people on the southern tip of the Florida Keys. Despite strong opposition from some residents, authorities there are considering the use of genetically modified mosquitoes to reduce the Aedes aegypti population.
The method has been endorsed by many scientists, and the U.S. Food and Drug Administration reported in May that it would not have any “significant environmental impact” on the Keys.
But opposition from residents has complicated the process and raised important questions about how city governments should approach the grave public health crisis. In the face of public opposition to what could be the most effective defense against Zika, must community leaders always obey residents' wishes? Or should the priority be to protect people from danger, regardless of their complaints?
The proposal and its opponents
Officials have proposed a test in the Key Haven neighborhood by Oxitec, a British biotechnology company linked to Oxford University that has carried out similar tests in parts of Brazil, Panama, and the Cayman Islands. Company scientist Darrid Nimmo says those tests reduced the population of dangerous mosquitoes by 90 percent.
Oxitec created a variety of the Aedes aegypti mosquito with a gene that prevents offspring from surviving. Mosquitoes are bred in laboratories and the males are released to mate in the wild. But their offspring die before adulthood, drastically reducing the mosquito population in the test area.
The Key West test would be Oxitec's first in the United States, and would be carried out for free as an evaluation, says Beth Ransom, a spokesperson for the Florida Keys Mosquito Control District (FKMCD).
Key West has been trying to hire Oxitec since a 2010 outbreak of dengue, a disease also carried by the Aedes aegypti mosquito, and some residents have been fighting the proposal tooth and nail since that time.
Key West real state agent Mila de Mier has become the face of the opposition, running an online petition against the test that has been signed by more than 168,000 people in about four years.
The overwhelming majority of the signers, however, are not Key West residents, says Michael Doyle, executive director of the FKMCD. “The last time we checked, 85 percent of the signers did not live in Florida,” he says. Doyle points to several surveys carried out by his team that suggest city residents are mostly behind the measure.
However, a poll published by researchers at Johns Hopkins University in May showed 58 percent of Key Haven residents opposed the project, although only 22 percent of the approximately 1,000 residents in the area responded. The poll (like every poll taken in Key West on this subject) was taken before Zika started to make U.S. headlines.
De Mier says Doyle and others at the FKMCD are trying to dismiss her petition and residents' concerns.
“I am not anti-GMO, a vegetarian or an activist,” she says. “I used to be a nurse. So when all this started, I said, 'This looks like a good idea.' But then I went to meetings with Oxitec, and the more I asked about the project the more uncomfortable I felt."
She argues that Oxitect has changed their story over the years, and that neither she nor many of the residents of Key West feel they’re being given reliable information. “First, they said that one out of every 1,500 males released turn out to be females. Now they say it's one in 10,000. Which is it?” says de Mier. (This factoid could turn out to have great importance, as only females bite humans and spread the Zika virus or other diseases).
Nimmo says it’s true the numbers have changed. The company's method of separating males and females during the pupae stage (using what is basically a sieve) is precise but imperfect. In 2012, it was indeed one in 1,500, he added, but the Panama test allowed the company to build more precise tools and reduce the number to one in 10,000. What's more, he added, it's been proven that the genetically modified female mosquito bite is no different from that of a wild mosquito.
De Mier also complains that 3 to 4 percent of the mosquito offspring with the modified gene manage to survive in the laboratory. Nimmo says that's true, but it's never been known to happen in the real world, where survival is much harder. Even if a few mosquitoes survive, he added, the overall population is still being reduced (probably by far more than even the most effective pesticides and insecticides, which can achieve only 30 to 40 percent control even at their most effective).
The risk for cities
Just last week, Miami-Dade County and Broward County in Florida recorded the first cases of locally transmitted Zika in the United States—meaning the first infected mosquitoes in the country.
It could be a matter of time before the disease spreads rapidly to other parts of Florida and the United States. Oxitec's mosquitoes could be the most effective defense any city has, but the potential solution faces strong opposition.
“People must give their consent. Without consent for the experiment, Oxitec should get out of here,” says de Mier. “Why does the municipal government want to experiment with biotechnology on me and my family against my will?”
Key West residents will vote on the Key Haven test project in November. The result will not technically be binding, but three of the five commissioners on the board of the FKMCD—including the one that represents the Key Haven area—have promised to follow voters' wishes.
Voting against the genetically modified mosquitoes could leave residents largely unprotected from the virus. Other city officials in Florida have trouble seeing how they could opt out of such a potentially effective solution, even in the face of public opposition.
“The truth is that if you ignore your constituents, they will vote you out. It is important to have them on your side when you do something," says Philip Stoddard, the mayor of South Miami and a biology professor at Florida International University. “But at the same time, some people are totally resistant to information, and they hate anything GMO. For them, perhaps you will have to wait for the disease to come. And then they will change their minds.”
No other method is as effective as Oxitec promises, and insecticides and pesticides damage the environment, Stoddard added. What's more, using too much insecticide on mosquitoes allows them to develop an immunity.
Stoddard acknowledged a problem with Oxitec's modified mosquitoes: deploying them in large cities could be very expensive, he says. But perhaps the arrival of Zika may lead voters to justify any expense to fight it, or perhaps it could be used only in small pockets of a city that are particularly high-risk for transmission of disease.
“I am completely in favor of using this method,” says the mayor. “Oxitec has done all the necessary tests to prove it works and is safe. But people will never be satisfied. It makes no sense.”