The bad news about Zika continues. The epidemic that has spread from Brazil to the rest of Latin America is now raging in Puerto Rico, with thousands of residents infected every day, and the first locally transmitted cases have been reported in the United States — more than a dozen during the past week or so in south Florida. Although the number of known locally transmitted cases is still small in this country, the fact that there are any at all is ominous (if not unexpected): It reflects that there are sufficiently large numbers of people with circulating Zika virus that mosquitoes are finding and biting them and then passing the virus along to another person or persons. We’re certain to see increasing — possibly exponentially increasing — numbers of cases.
Zika causes babies to be born with small heads and malformed brains, and probably other, more subtle defects. It also causes some adults to suffer the progressive paralysis of Guillain-Barré syndrome. Several companies are working on a vaccine, but because of technical issues and regulatory requirements, none is likely to become commercially available before the end of the decade.
Congress and the Obama administration have been at odds about how much additional funding is necessary to respond to the Zika outbreak, but far more significant is the bumbling of Obama’s Food and Drug Administration, which is blocking progress on a vital tool to control Aedes aegypti mosquitoes, which carry and transmit not only Zika but also the viruses that cause dengue fever, chikungunya, and yellow fever.
Using molecular genetic-engineering techniques, the British company Oxitec (a subsidiary of America-based Intrexon) has created male Aedes aegypti mosquitoes with a mutation that makes them need a certain chemical (the antibiotic tetracycline) to survive. Without it, they die — as do their offspring — before reaching maturity. If these males are fed a diet containing tetracycline (to keep them alive long enough to reproduce) and then released into the wild over several months, the result is a marked reduction in the mosquito population. Because male mosquitoes don’t bite, they present no health risk, and, because their progeny die before they can reproduce, no genetically engineered mosquitoes persist in the environment.
This approach has already been widely and successfully tested abroad. Efficacy trials of Oxitec’s genetically engineered mosquitoes across Brazil, Panama, and the Cayman Islands all resulted in greater than 90 percent suppression of the wild population of Aedes aegypti mosquitoes, and the World Health Organization has endorsed Oxitec’s product. (Aedes aegypti mosquitoes are an invasive species in the Americas, so there’s no possibility that reducing their numbers will disrupt natural ecosystems.)
But U.S. regulators have been paralyzed, unwilling to permit even small-scale field testing. The story behind this monumental snafu has several elements, all of which were avoidable.
The first problem is that the FDA and the Agriculture Department are completely out of sync. The Oxitec mosquito should be regulated by the USDA’s Animal and Plant Health Inspection Service, which has the authority and expertise to oversee field trials and commercialization of genetically engineered insects. (The technique of using sterile insects to control pest populations was developed in the 1940s by the USDA’s E. F. Knipling, who used irradiated males to eradicate the New World screwworm, an evil-looking parasite that attacks livestock and humans, from the U.S. and much of North America.) But for a combination of reasons, including budgetary concerns and antagonism to genetic engineering among some senior USDA officials, the department demurred. It ceded jurisdiction to the FDA, which is completely unqualified to review the mosquito and unwilling to move its approval along.
The FDA regulates the genetic material introduced into the mosquito as a “new animal drug” — similar to the way it regulates flea medicines and analgesics for dogs and cats. The rationale is that introducing DNA into the genome of the mosquitoes is analogous to dosing them with a drug. (This was an unwise and unnecessary policy decision, but that is a story for another day.) According to statute, in order to be marketed, the genetic material, like other “drugs,” must be shown to be safe and effective for the animal.
That presents a problem, because to approve the Oxitec insect, the FDA would need to employ logic that only a regulator could love: Regulators would somehow have to conclude that the genetic material that causes a male mosquito to self-destruct after producing defective offspring is safe and effective for the mosquito. The FDA could find itself tied up in legal knots if its ultimate approval of the insect were to be challenged in court by environmentalists or anti-genetic-engineering activists.
Nevertheless, in 2011 the FDA, apparently whistling past the graveyard, accepted Oxitec’s application to perform a field trial in the Florida Keys. But because of timidity, incompetence, or under-the-radar political considerations, not a single test mosquito has yet been released. In May of last year, the FDA announced that a proposed environmental assessment of the trial would be issued, and a draft, which concluded there would be “no significant impact,” was finally released this March. It went out for public comment, after which the FDA will analyze the comments and decide whether to issue a final assessment or prepare a complete environmental-impact statement — which could take years.
Given the impending threat of widespread Zika infections, and their sequelae, in the United States, the FDA’s performance — or lack of it — is outrageous.
