Robert F. Kennedy Jr. says a worm ate part of his brain. Experts said that’s unlikely.

A presidential candidate said doctors found a worm in his brain. That worm, he said, also consumed some of his brain tissue while it was in there.

The New York Times reported May 8 that in a 2012 deposition during divorce proceedings, Robert F. Kennedy Jr. said a doctor believed an abnormality on his brain scans in 2010 was "caused by a worm that got into my brain and ate a portion of it and then died."

Kennedy, an independent presidential candidate, told the Times he didn’t know what kind of parasite was in his brain, but he said he might have contracted it while he was traveling through South Asia. Infectious disease experts and neurosurgeons told the Times that they believed it was "likely a pork tapeworm larva" or Taenia solium. 

Could a worm have eaten part of Kennedy’s brain? Experts told PolitiFact it’s unlikely.

"It is certainly possible that the larval form of some parasites (including Taenia solium) can ‘accidentally’ migrate to the human brain. It is absolutely incorrect that this form of T. solium (e.g., neurocysticercosis) ‘eats’ brain tissue," said Stephen Felt, a comparative medicine professor at Stanford University. "In fact, the human immune system recognizes it as foreign material and walls it off by forming a cyst and the larva then dies."

PolitiFact contacted Kennedy’s team but did not hear back.

Infections in the body resulting from larval cysts of pork tapeworm cause cysticercosis, and when found in the brain, the condition is called neurocysticercosis. This parasitic infection can cause seizures and can be fatal.

According to the Centers for Disease Control and Prevention, people contract neurocysticercosis by swallowing microscopic eggs in the feces of a person with an intestinal pork tapeworm. People with a pork tapeworm infection, people who live with someone who has a pork tapeworm and people who consume food made by someone infected with pork tapeworm are more likely to get neurocysticercosis.

Andrea Winkler, visiting professor of global health and social medicine at the Harvard Medical School, told PolitiFact she found the claim of a worm eating brain tissue "far-fetched."

"The larvae may cause inflammation, but brain tissue is not ‘eaten,’" Winkler said. "There are also other parasites that may travel to the brain, but they obey similar principles." 

Winkler said some parasites, such as the amoeba Naegleria fowleri, can "eat" brain tissue, but this is "very rare" and would result in a "progressive, deadly disease." Naegleria fowleri can live in warm fresh water; when water with this amoeba enters a person’s body through the nose, it travels up to the brain and destroys brain tissue. 

Pria Anand, assistant professor of neurology and director of Boston University’s neurology residency program, said that if  Kennedy was referring to a pork tapeworm, he was correct in saying it "might have lodged in his brain and then died." But the symptoms wouldn’t have resulted from the worm "eating" his brain.

Instead, Anand said, the symptoms would have been caused by "the human body’s immune/inflammatory response to the dying worm, or from the physical presence of a calcified dead worm, which remains lodged within the brain."

Neurocysticercosis causes epilepsy, and depending on where the cyst is, Anand said, it could also cause blindness, increased pressure in the brain, weakness and headaches. She said it could also remain dormant for years.

Kennedy told the Times he recovered from the memory loss and mental fogginess he experienced in 2010 and did not experience "aftereffects from the parasite." Felt said that although we don’t know whether Kennedy suffered or continues to suffer symptoms, the disease can be devastating and is common in areas "where humans and pigs coexist under unsanitary conditions." 

"However, it is also possible for individuals to never realize they have been infected as they show no symptoms," he said. "These asymptomatic patients are usually discovered by accident by brain image studies."

Felt said the symptoms that manifest — seizures, blindness, headaches, cognitive losses and death — depend on the location, number and severity of the associated immune reaction to the cysts.

"Many folks with neurocysticercosis never show symptoms," he said. "In these cases, the brain cyst may be low in number, localized in noncritical areas of the brain and/or the associated immune response is quite mild."