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Zika Virus Outbreak

Is It Really GMOs or Insecticides? What's Behind the Bogus Zika Rumors

Image: BRAZIL-HEALTH-ZIKA-MICROCEPHALIA

Physical therapist Isana Santana treats Ruan Hentique dos Santos, who suffers from microcephaly, at Obras Socias Irma Dulce hospital in Salvador, Brazil on Jan., 28, 2016. CHRISTOPHE SIMON / AFP - Getty Images

It's hard enough battling a fast-spreading epidemic, one that's mystifying even the leading experts. And now a new front has opened in the global health war against the Zika virus: quelling the rumor mill.

On Wednesday, the myths took to the stage on Capitol Hill as Florida Rep. John Mica, armed with a big yellow spray bottle of mosquito repellent, asked whether bug spray would help or hurt people.

"They have this, but they also found it causes cancer," Mica said at the House subcommittee hearing on paying for Zika readiness. "Is this stuff good to use and are you guys recognizing that? Is the cure worse than the disease?"

Dr. Anne Schuchat didn't even flinch as she answered. The spray, called permethrin, is recommended by the Centers for Disease Control and Prevention and the World Health Organization for use on clothing to keep Zika-carrying mosquitoes at bay.

"Our website has a link to what is okay and what is not," the CDC's deputy director answered.

Permethrin is on the list of safe products, along with DEET, which worries many average consumers but which CDC says is safe to use on all but the youngest babies.

Image: Dr. Andrew McKemey releases Oxitec male mosquitoes in Brazil
Dr. Andrew McKemey releases Oxitec male mosquitoes in Brazil. A British company that genetically engineers mosquitoes to produce “dud” offspring says it’s reduced the number of mosquito larvae by 80 percent in one small Brazilian city. They hope to expand operations now to fight Zika, dengue and other dangerous viruses. Oxitec

Permethrin is a pyrethroid, a chemical based on a natural compound made by chrysanthemums. The Environmental Protection Agency says it can cause cancer if people eat it, but it's not easily absorbed through the skin and it's supposed to be sprayed on clothing, anyway. The International Agency for Research on Cancer says it cannot determine if permethrin causes cancer or reproductive damage to humans.

Mica's query is one of dozens of questions about Zika and what's really causing a rise on cases of birth defects in Brazil. Could it be the larvicides used to defeat mosquitoes that lay eggs in water? Could it be the genetically modified mosquitoes being released in parts of the country? How about the radiation-treated mosquitoes? Or vaccines?

Risk communications experts say such reports are par for the course when there's a new disease like Zika.

"There's nothing weird about activists for a cause — any cause — trying to appropriate a hot news peg for use as a teachable moment. They are smart to grab onto the coattails of the issue," said Brooklyn, New York communications consultants Peter Sandman and Jody Lanard.

And the spread of Zika and birth defects is a "high-outrage" event. "We know very few people, and no parents, who can look at a news photo of a microcephalic infant without shuddering," they wrote in an email to NBC News.

The risk to any given person may be low, they said. "But it's the outrage, not the hazard, that provokes people's strong emotional response."

And there are plenty of people who question the safety of pesticides and genetically modified organisms (GMOs), said risk consultant David Ropeik.

"Pesticides and GMOs are classic bogeymen to such folks, who are always on the lookout for evidence to support what for them is a really powerful central animating belief," Ropeik said. "So up pops something going wrong in the natural world and these folks are quick to interpret that new phenomenon through those lenses, working up and promoting a set of facts that fit their values."

And Zika has caused a near perfect storm of doubt and uncertainty.

"It's new. It's got an exotic name. It affects kids," Ropeik told NBC News. And even the scientists admit they are baffled by some of what is happening in Brazil.

The WHO, concerned enough about the rumors and the media coverage they generated, put up a point-by-point rebuttal.

It says there's no evidence that vaccines, mosquito larvicides or altered mosquitoes are causing the rise in birth defects.

Microcephaly and Zika Present a Public Health Emergency, WHO Declares 0:25

But Sandman and Lanard say it's not enough to simply rebut the rumors.

"Be empathic toward those who believe the rumor. You can't convince people the rumor is false if it's clear you think they're idiots for believing it," they advise.

"Demonstrate that you have taken the rumor seriously. 'Here's what we did to look into the rumor. And here's what we learned,'" they said.

Fears about larvicides or genetically engineered mosquitoes possibly causing birth defects are not completely silly. Both interfere with the normal development of baby mosquitoes, so it would not be illogical for a non-expert to ask if they might not also interfere with a human baby's development.

WHO merely says that people cannot take in enough larvicide in drinking water to affect them. But other experts say the chemical, known as Nylar or pyriproxyfen, affects a hormone in insects that interferes with development. It doesn't affect adult insects and it doesn't affect mammals.

With genetically engineered mosquitoes, a gene is added that makes the sperm work at first, but the resulting larvae die quickly. Such a gene could not be transferred to a pregnant woman, or any human, by the bite of a mosquito — and it's the females that bite, anyway, not the GM males.

Other modified mosquitoes being tested carry a bacteria called Wolbachia. It stops viruses from growing in the mosquitoes and also seems to affect their ability to produce offspring. Again, the effect is on insects, not mammals.

The radiation used to sterilize mosquitoes in yet another approach is not the kind that can persist and be passed along. It's a one-time event, like the application of heat or an x-ray, as opposed to a radioactive contamination event, when a radioactive gas or other substance actually gets onto something or someone and emits dangerous radiation.

And vaccines have been shown to be safe for decades, despite a few very vocal activists.

It's not much fun to defend chemicals, Lanard and Sandman say.

"But because the virus is natural, there's no one to blame, no enemy except nature. It's just a virus," they said.

"How much more satisfying to blame the evil chemical industry that invents and markets pesticide after pesticide after pesticide, until it's nearly impossible to find a person or animal without pesticide-contaminated tissues," they added.

"GMOs in particular tap into nearly all the outrage factors we know about, and pesticides aren't far behind."

While CDC and WHO are very upfront about doubts, they say evidence is growing every day that Zika is involved in what appears to be a very real increase in birth defects.

While Zika itself was thought to be a fairly harmless virus, there are other usually mild viruses that cause devastating birth defects, such as rubella and cytomegalovirus. Now that Zika is being found in the brains of affected babies, it's becoming more and more the only suspect.

And the best way to prevent Zika infections is to stop the mosquitoes that carry the virus.