The Zika virus is real. It really does cause microcephaly and other birth defects. And it definitely didn’t come from the Rockefellers.

But as the Zika virus continues to spread locally in the Miami area, conspiracy theories about its origins are spreading, too. Just last week, for example, some Miami Beach protestors argued against aerial pesticide spraying in a city council meeting by claiming that Zika does not cause microcephaly and by alleging that the CDC is being controlled by pesticide companies.

If left unchecked, the people behind these bogus theories could create a significant threat to public health.

“They’re leaving the most vulnerable people open to these diseases,” Dr. Tara C. Smith, a Kent State University infectious disease epidemiologist who has been cataloging Zika conspiracy theories, told The Daily Beast.

The “ultimate irony,” she says, is that the perpetrators behind these conspiracy theories profit from them while simultaneously alleging that a shadowy cabal of scientists and government figures are raking in money from Zika.

Take, for example, the theory recently promoted by anti-vaccine website Health Impact News that the Zika virus is “a masterpiece of public mind control.” In a post that has already been shared 24,000 times on Facebook—with all of the ad revenue that number of eyeballs entails—writer John P. Thomas flatly and falsely states that Zika “does not cause microcephaly.” The truth, he believes, is far more sinister.

“[I]f Zika could be connected to some other horrible consequence, such as microcephaly or paralysis for example, then people would insist that we create a Zika vaccine and would insist that every person on planet Earth take it,” wrote Thomas. “They would be willing to give up basic individual freedoms for the benefit of society, which is always the goal of mind control programs.”

His prediction: “Zika will be one of the tools used by mind controllers and the ruling elite to move us toward mass vaccination and total government control over our lives.”

After 15 years of tracing the conspiracy theories that tend to swirl around infectious disease outbreaks, Smith is unfazed by this latest hare-brained notion.

“It doesn’t even surprise me anymore,” she said. “They have to get more and more outlandish as the science comes in that shows that Zika does cause microcephaly and these other neurological issues, so now they have to [promote] real far-out conspiracy theories.”

To be fair, they were already pretty far-out to begin with. Smith has already swatted away some truly bizarre Zika conspiracy theories on her blog. Was the current Zika outbreak caused by genetically-modified mosquitoes from the British company Oxitec as websites like Alex Jones’s InfoWars have implied? No, and as Smith told The Daily Beast, “whoever [first] wrote that has obviously not taken more than an intro bio class.”

Are vaccines causing microcephaly, as flat earther David Wolfe pointedly asked? Nope. Zika is causing microcephaly. Did the Rockefellers invent Zika to “kill millions of people?” Come on now.

The conspiracy theories have gotten so bad that the World Health Organization has had to make a specific website for “dispelling rumors around Zika and complications.”

With regards to the Oxitec conspiracy theory, the WHO anti-rumor FAQ explains that “only genetically-modified male mosquitoes are released, so there is no risk of disease transmission to humans because only females bite humans.” The WHO also makes it crystal clear that “there is no evidence linking any vaccine to the increases in microcephaly cases” that have shown up in Brazil.

But for the true believers, public denials from respected sources like the WHO only make the conspiracy theories seem more credible.

“I’m not writing for those who are completely convinced—those who, just by the virtue of me writing about it, assume that I’m in the pocket of Big Pharma,” Smith told The Daily Beast. “I know I’m not going to convince them. Usually who I try to convince are those people who have heard these conspiracy theories—maybe through friends of friends, maybe through social media—but don’t really know what to think about them.”

Although conspiracy theories about infectious disease have been with us for centuries, Smith says that the internet has “facilitated” their spread in cases like Ebola and Zika, allowing misinformation to move instantaneously between countries and hemispheres.

A May study in the journal Vaccine by Johns Hopkins and George Washington University researchers found that Twitter conversations in particular were helping to drive pseudoscientific, anti-vaccine commentary around Zika during the first half of 2016.

“Even though the science is relatively clear, we found many conspiracy theories that could be affecting people’s health-related decisions, such as whether to vaccinate,” study co-author and George Washington professor Dr. David Broniatowski said in a press release. “Unfortunately, the people most affected are from the most vulnerable communities, with little access to the facts.”

Some of these conspiracy theories have taken a firm hold in the United States. A February Annenberg Public Policy Center survey found that 22 percent of Americans believe the current Zika outbreak was caused by genetically modified mosquitoes. The same survey found that 20 percent of Americans falsely believe that “scientists think vaccines have caused microcephaly.” And despite evidence to the contrary, 19 percent of Americans believe that “scientists think that if a pregnant woman drinks water sprayed with a larvicide to stop the spread of mosquitoes, it can cause microcephaly.”

It has been months since this polling was conducted but as Dr. Mark Dredze, a John Hopkins University professor and lead author of the Vaccine study said, “Once people have made up their minds about something it’s hard for them to change their opinions.”

At worst, these conspiracy theories can convince people in Zika hot spots like Miami that they should fear vaccines, scientists, and the government more than the costly birth defects that Zika can cause.

CDC Director Dr. Thomas Frieden has stated that lifetime health care costs for a microcephalic child can fall between $1 and $10 million. People who are not pregnant can still facilitate the transmission of Zika to a pregnant woman through sex or by being bitten a mosquito that then bites her. Essentially, this means that anyone who refuses to take Zika seriously based on the theory that it does not cause microcephaly is by, default, subjecting others to the potentially devastating consequences of that false belief.

“You’re really leaving people who don’t have access to this information [and] in some cases don’t have access to prevention wide open to viral infection,” Smith told The Daily Beast, referring to the people who propagate these theories.

But no matter how vehemently the CDC and the WHO quell the misinformation around Zika, Smith says that the infectious disease conspiracy theorists aren’t going anywhere.

“You have these people and that is their financial model and they do great at it,” she said. “There’s always going to be some new pathogen, some new scare that they can profit off of.”

In the meantime, she wants the diehards to know that she’s not exactly getting rich from refuting their theories.

“They don’t see what kind of cars we actually drive,” she joked.