Tapeworms have been making headlines ever since an investigation by The New York Times turned up a deposition Robert F. Kennedy Jr. gave in 2012. In it, the independent candidate running for president claimed doctors found a one inside his brain. Infectious disease experts and neurosurgeons that the Times spoke with agreed that it was likely a common pork tapeworm. Or rather, a cyst created by pork tapeworm larvae.

　　I’m particularly interested in this topic because I, too, had a tapeworm. How do you catch such an infection?

　　I called Philip K. Budge, Associate Professor of Medicine at Washington University in St. Louis, to find out. Budge sees patients with parasite infections in the universitys infectious disease clinic, and conducts research into parasitic worms in Africa. He also helped the Centers for Disease Control (CDC) investigate and respond to parasitic diseases in his former role in the Epidemic Intelligence Service.

　　“In areas where pork are infected with Taenia solium [the technical name for the pork tapeworm], if you eat undercooked pork, you get a tapeworm in your gut,” Budge says. “Having a tapeworm in your gut isn’t a pleasant thought, but it usually doesn’t cause us any trouble.”

　　I don’t know where I got mine. Budge asked me if I’d ever eaten undercooked pork, beef, or freshwater fish. I have, often in parts of the world where parasites are common. I once ate sketchy sushi on a barge floating near an open sewer in Havana, Cuba. If I had to pick a favorite food, it would be something grilled on a street in a developing country.

　　Like most people, I didn’t know I had a tapeworm until it died, and I passed the two-foot long worm in a bowel movement. Subsequent tests turned up no further signs of infection.

　　Budge says that’s a common course. Tapeworms, whether they’re of the variety that use pigs, cattle, or fish as an intermediary host, don’t tend to cause negative or even noticeable impacts in the human body.

　　“The vast majority of people just pass the worm when it’s dead and then they’re done,” says Budge. “More than one billion people worldwide have some sort of worm infection; it’s not a big deal.”

　　“Where we do see trouble is when people poop out tapeworm eggs,” Budge says. So this is where we can start talking about RFK Jr.,’s brain worm, which it appears wasn’t a worm, but rather worm larvae.

　　Budge is dismissive of media reports that exaggerate the risks associated with infection, or which artificially boost the rare incidents in which a human may be infected by multiple worms at once. The doctor says there’s absolutely no need for parasite cleanses or other wellness cures that claim to remove or prevent parasites.

　　A worm parasite can’t reproduce inside a person, according to Budge. If you’re a frequent traveler, and you happen to ingest larvae and develop a tapeworm or roundworm in your gut, then thats the only worm that will develop from that infection.

　　“It has to have some stage of its lifecycle where it leaves and is then reintroduced [to a human host],” he says. “People have these terrible thoughts that worms are going to burst out of them Alien-style. That does not happen. You pick up a worm while you’re traveling, it lives out its normal life, dies, and then goes away. You’re cured.”

　　His biggest piece of advice? “If you pass a worm, don’t freak out,” says Budge, who says he spends more time convincing people that they shouldn’t be worried about parasites than he does treating them.

　　“Where we do see trouble is when people poop out tapeworm eggs,” Budge continues.

　　So this is where we can start talking about RFK Jr.,’s brain worm, which it appears wasn’t a worm, but rather worm larvae. Budge says that larvae “blow up a bubble” to “make room for themselves” after migrating through the blood stream and infecting a host’s muscle or brain tissue, forming a cyst.

　　But you don’t get the cyst from eating undercooked pork.

　　“To get the cyst, you have to eat something that’s been contaminated with eggs from someone else’s poop,” he says, meaning human poop, not animal poop. Which is why I developed a worm rather than a cyst—I ate undercooked meat, not human feces.

　　While no one intentionally eats human feces, it can contaminate food through unwashed hands or unsanitary crop fertilization practices.

　　“…A worm that got into my brain and ate a portion of it and then died,” The New York Times reported that Kennedy stated in a deposition. Kennedy went on to associate the alleged worm with short-term memory loss, longer-term memory loss, and cognitive problems. His campaign declined a request from the paper to release the candidates’ medical records, but Kennedy did challenge his rivals—Donald Trump and Joe Biden—to a sort of worm off.

　　“I offer to eat five more brain worms and still beat President Trump and President Biden in a debate,” Kennedy tweeted. “I feel confident in the result even with a six-worm handicap.”

　　Budge says that tapeworm larvae don’t actually eat any of the host’s tissue. They just absorb nutrients, and that the fluid inside the cyst they create pushes the other tissue out of the way.

　　“When you look at a three-dimensional image of somebody’s brain with neurocysticercosis [the technical term for tapeworm larvae infecting a brain], it looks like Swiss cheese,” Budge says. “It’s terrifying to look at because it looks like somebody’s just punched out holes in somebody’s brain, but the brain tissue hasn’t been damaged, it’s just been pushed aside.

　　Budge explains that, when the larvae die and the cyst collapses, it can leave behind minor calcification and scar tissue. While neither the cyst nor its remnants impair mental function on their own, a really bad infection with numerous cysts in the brain can lead to seizures.

　　The cysts themselves inhibit the body’s immune response and don’t create inflammation on their own. When the larvae die, and the cysts collapse though, that inflammation inhibitor also disappears. Inflammation is the body’s response to infection, but if it applies pressure inside the brain, it can cause seizures.

　　If you have one cyst in there, and it dies on its own, and the inflammatory response doesn’t provoke a seizure, then you’re not going to have problems from that in the future,” Budge explains. Tapeworm cysts shouldnt cause memory loss or cognitive problems, according to his experience.

　　Budge says that a lot of tapeworm infections, like mine, are caused by “adventurous eating.” So, his advice is clear: “Don’t be an adventurous eater.”

　　You should also wash your hands before touching food, drink bottled or filtered water, and make sure any meat or fish you consume is thoroughly cooked.

　　“People usually know when food seems a little sketchy,” says Budge. “Don’t eat that.”