The mosquito species Aedes aegypti transmits viral diseases, including Zika, dengue, chikungunya, West Nile, and yellow fever, between human hosts. For most of these viral diseases, there are no vaccines and no effective medicines. So until recently, public-health officials have had to use old, low-tech approaches to controlling the mosquito vector and reducing the incidence of infections: pesticide sprays, public education about exposure (DEET, mosquito nets, and clothing that covers as much skin as possible), and control of breeding areas (water in flower pots, tires, drains, etc.).
Oxitec, a British subsidiary of the American company Intrexon, has created a new way to control Aedes aegypti. Male mosquitoes are bred in the laboratory with a specific genetic mutation that, in the absence of a certain chemical, causes their offspring to die before reaching maturity. Male mosquitoes do not bite, so their release presents no health risk, and, because their progeny die, the genetically engineered mosquitoes do not persist in the environment. Releasing the males over a period of several months causes a marked reduction in the mosquito population.
In field tests conducted in Brazil, the Cayman Islands, Malaysia, and Panama, Oxitec has shown that the release of these genetically engineered male mosquitoes has consistently reduced wild populations by more than 80 percent, and the most recent field trials show greater than 90 percent reduction. In 2014, on the basis of these field trials, Brazil’s regulatory authority approved the commercial release of these mosquitoes. Brazil approved Oxitec’s approach because the traditional approaches to mosquito control were failing to protect the country’s inhabitants from A. aegypti–borne viral diseases. The apparent association of Zika-virus infection with microcephaly in babies born to infected mothers has only added to the urgency.
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Among the places where Aedes aegypti lives is the southeastern United States. In 2011, the Florida Keys Mosquito Control District — which, like Brazil, was finding other options for mosquito control insufficient — requested the Food and Drug Administration (FDA) to allow a field trial of Oxitec’s mosquitoes. Counterintuitively, that was the agency Florida applied to because in 2009 the FDA asserted regulatory jurisdiction over all genetically engineered animals. Five years after Florida’s request, the FDA has failed to render a decision on this small-scale field trial of a product that has undergone successful field trials in other countries and is approved for sale in Brazil.
#share#What explains this unconscionable five-year delay?
Environmental risks? The genetically engineered males die, and their offspring die before reaching maturity. A. aegypti is a relatively recent arrival in the Western Hemisphere from Africa; thus, it is properly considered to be an invasive species whose elimination would restore the habitats to their prior ecology. The males released in field trials contain a fluorescent marker for monitoring their numbers and location.
Human-health risks? Male mosquitoes do not bite, only females do, and adult females do not carry the inserted genes; only modified males are created and released. The inserted genes are known to be non-toxic and non-allergenic, so humans are not exposed to any contact that could be harmful. Indeed, human exposures to A. aegypti mosquitoes are reduced as their wild populations drop off dramatically. The real risks to humans are clearly not from the proposed remedy, but from the insect-borne diseases. And, as with the lead contamination of water in Flint, Mich., and malaria in tropical countries, the poor bear the brunt of this public-health challenge.
The Obama administration has failed to provide adequate direction, perhaps a manifestation of its notorious strategy of “leading from behind.”
Eight months have passed since the FDA promised last May to publish for public comment a routine environmental assessment of Florida’s request to conduct a field trial. Only after the FDA reviews the comments will the agency consider whether to grant approval — merely for the field trial. Given the lack of expertise and risk aversion at the FDA, commercial approval is probably at least a decade away. This delay is unnecessary and irresponsible, and it violates the essence of the contract between society and our government regulators. Lifetime tenure for civil servants — which itself exacts costs in efficiency — is supposed to free regulators to consider only the public interest as they render decisions. Instead, it has given us the worst of both worlds: On the one hand, it has become virtually impossible to remove incompetent, truculent, or adversarial federal regulators; on the other, we are forced to live with decision-making by officials who are frequently influenced by perceived risks to their careers if a new product should cause an unanticipated problem.
The bottom line is that we are experiencing a crisis of leadership. The Obama administration has failed to provide adequate direction, perhaps a manifestation of its notorious strategy of “leading from behind.” It allowed the FDA, which lacks expertise or experience with genetically engineered insects, to wrest regulatory oversight from the USDA, which had routinely approved important biological insect-control agents, such as the sterile screwworm fly. Without relevant expertise, the FDA has not surprisingly been ill equipped to review the application expeditiously.
The FDA’s timidity in reviewing the request for a field trial, let alone moving Oxitec’s mosquitoes toward commercial approval, argues that it is long past time to shift the oversight of such products to a more responsible and responsive agency. In the meantime, the delay in testing the Oxitec mosquitoes bodes ill for other innovative approaches to protecting our population against the mosquitoes that transmit Zika and other viral diseases. That’s bad for innovation, for economic growth, and, above all, for the future victims who could have been spared.