VERIFYING how a parasitic worm can get into your brain

Independent presidential candidate Robert F. Kennedy Jr. allegedly contracted a parasitic worm more than a decade ago, which he claimed ate a portion of his brain before the worm died. 

Kennedy revealed in a 2012 deposition obtained by the New York Times that he suffered from memory loss. He also said he was diagnosed with mercury poisoning that he attributed to his diet around the same time the parasite was found. 

The Times reported that Kennedy said he consulted with neurologists in 2010 when a friend voiced concerns about his memory loss. Kennedy said he was told that a dark spot discovered in his brain scans could be a tumor. However, Kennedy reportedly said in the deposition that a doctor told him the spot could be caused by “a worm that got into my brain and ate a portion of it and then died.” 

Here’s what we can VERIFY about how parasitic worms can infect the brain and the effects they can have on a person’s health.

THE SOURCES

• Centers for Disease Control and Prevention (CDC)
• Cleveland Clinic
• California Department of Public Health (CDPH) 
• Article by John E. Greenlee, M.D., a professor of neurology at the University of Health, for Merck Manual
• Lorin Ferrins, Ph.D., associate professor of chemistry and chemical biology at Northeastern University
• Janine Caira, professor of ecology and evolutionary biology at the University of Connecticut
• Peter Hotez, M.D. Ph.D., dean of the National School of Tropical Medicine at Baylor College of Medicine

WHAT WE FOUND

How does a parasitic worm get into the brain?

There are multiple types of parasitic worms that can cause brain infections.

Two “major brain worms” are the pork tapeworm known as Taenia solium, and parasitic roundworms that are commonly found in the intestine of dogs (Toxocara canis) and cats (Toxocara cati), Peter Hotez, M.D. dean of the National School of Tropical Medicine at Baylor College of Medicine, told VERIFY.

Though multiple types of worms can infect the brain, the pork tapeworm causes “the most cases of brain infection in the Western Hemisphere,” John E. Greenlee, M.D., a professor of neurology at the University of Health, wrote for Merck Manual. 

Kennedy’s campaign didn’t specify the type of worm found in his brain and his diagnosis hasn’t been confirmed. But doctors consulted by the New York Times speculated that Kennedy described symptoms of an infection with larvae from the pork tapeworm.

People can get taeniasis, or an intestinal infection with the adult stage of the tapeworm, from eating raw or undercooked pork that contains larval cysts. Once these larval cysts are in a person’s intestine, they can develop into adult tapeworms and produce a large number of eggs, the California Department of Public Health (CDPH) explains. 

Cysticercosis is a tissue infection caused by the larval, or young, form of the tapeworm. When the infection affects the brain, it’s called neurocysticercosis. 

People can get cysticercosis after swallowing eggs from a pork tapeworm. The eggs hatch in the small intestine and larvae migrate throughout the body before forming cysts, according to the CDPH. 

When a person has neurocysticercosis, these larvae adhere to the brain and form cysts, or pockets or fluid that grow around the larvae, which can cause a variety of complications, according to the Cleveland Clinic. 

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What symptoms can neurocysticercosis cause?

According to the CDC, the symptoms of neurocysticercosis depend upon how many cysts a person has and where they are located in the brain. 

The cysts can sometimes stay on the brain “for a long time without causing symptoms,” the Cleveland Clinic says. 

But the infection can also cause neurological symptoms such as seizures, headaches, confusion, lack of attention, difficulty with balance and excess fluid around the brain. The infection can lead to death in some cases, according to the CDC. 

When the cysts on the brain start to die, “your immune system recognizes them as invaders and causes inflammation to attack them,” the Cleveland Clinic explains. But, if there are a lot of cysts, they can put pressure on the brain even before they die. 

This inflammation or pressure can lead to life-threatening brain swelling, and cause seizures, headaches and other neurological issues, according to the Cleveland Clinic. 

When cysts die, they can also leave behind hard patches called calcifications in the brain. These calcified nodules are surrounded by fluid and can also lead to seizures, the Cleveland Clinic says. 

Some cases of infections caused by tapeworm larvae do not require treatment, the CDC says. However, they are generally treated with anti-parasitic and anti-inflammatory drugs. Surgery is sometimes necessary to treat cysts in certain locations or to reduce brain swelling. 

Some people may also need treatment for symptoms the infection causes, such as seizure medication.

Do parasitic worms eat brain tissue?

Though these infections can cause damage, parasitic worms do not “eat” brain tissue, as Robert F. Kennedy Jr. suggested, multiple experts told VERIFY. 

Kennedy’s description of a worm eating part of his brain is a “misnomer,” according to Edward Jones-Lopez, M.D., an infectious disease specialist with Keck Medicine of USC, and scientists at Northeastern University.

A worm “isn’t actively eating tissue” in the brain or elsewhere in the body, Lorin Ferrins, Ph.D., an associate professor of chemistry and chemical biology at Northeastern University, said in an article. 

Instead, they “absorb all of their nutrients through the outer surface of their body,” Janine Caira, a professor of ecology and evolutionary biology and tapeworm expert at the University of Connecticut, explained. Tapeworms do not have mouths or “elements of the digestive system,” Caira said.