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  • Writer's pictureP.K. Peterson

Worms That Target the Brain

“It’s not what you eat that will kill you as much as what is eating you.”

Orin Woodward, American author

“It is unfortunate that these parasitic infections, which disproportionately impact individuals in low- and middle-income countries, only get the attention and discussion when a high-profile individual gets infected.”

Shira Shafir, PhD, MPH, Associate Professor, Department of Epidemiology, UCLA


The May 8, 2024 New York Times article “R.F.K., Jr. Says Doctors Found a Dead Worm in His Brain” prompted me to write this week’s post. In the article, the New York Times reported that presidential candidate Robert F. Kennedy, Jr. (RFK, Jr.) had faced “previously undisclosed health issues including a parasite that he said ate part of his brain.” In today’s Germ Gems, I focus on helminths—parasitic worms that cause brain disease—and, more specifically, hone in on Taenium solium (aka pork tapeworm), the most likely culprit in Mr. Kennedy’s case.

Helminths that cause brain infections. Various types of parasitic worms cause helminthiasis (worm infections). These include nematodes (roundworms) and cestodes (tapeworms).

Larvae from T. solium (pork tapeworm) are the most common helminthic cause of central nervous system infection worldwide. Other helminths can also cause brain disease, albeit far less commonly. These include: Toxocara spp.(roundworms); Angiostrongylus cantonensis (rat lungworm); Strongyloides stercoralis (a nematode that threatens immunocompromised people); Paragonimus spp. (lung flukes); Echinococcus spp. (the cause of hydatid disease); and Gnathostoma spp..

Life cycle of the pork tapeworm. Taeniasis is an intestinal infection with adult pork tapeworms (T. solium) that follows ingestion of raw or undercooked pork. The preadult and adult tapeworm are found in the small intestine where they can cause taeniasis (gastrointestinal symptoms).

Adult tapeworms can grow to longer than 12 feet (3.5 meters), and each segment (proglottid) of the tapeworm is able to produce eggs. A mature tapeworm produces more than 50,000 eggs per day. The proglottid segments are full of eggs and are found in the host as well as the external environment when contaminated by human feces.

After people eat food contaminated with the tapeworm eggs, secretions in the stomach cause the eggs to hatch into larvae. (Often, it is pork prepared by others—the so-called  “fecal fingers of fate”—that is responsible for the transmission of the parasite.) When larvae travel through the bloodstream and into the brain they form cysts which can cause neurocysticercosis.

What is neurocysticercosis? Neurocysticercosis occurs when T. solium cysts take hold in the brain. While these cysts can provoke a variety of symptoms, the type and severity depend on the number and location of cysts, as well as on the host’s immune response to the parasite. In some cases, infected people are asymptomatic.

One of the most common clinical manifestations of neurocysticercosis is seizures. (For example, neurocysticercosis is the leading cause of seizures in Mexico.) Other symptoms include headaches, blindness, meningitis, and dementia. Neurocysticercosis is widely considered the world’s leading cause of preventable epilepsy.

Diagnosis is most commonly made by brain computed tomography, which may be confirmed by serological tests. Treatment includes epileptic therapy and a long course of the medication praziquantel and/or albendazole. Surgical removal of cysts is sometimes necessary.

Both taeniasis and neurocysticercosis are rare in the U.S. They are, however, common in countries where pigs roam freely and sanitation (hygiene) is poor.

Back to RFK, Jr. In an article on May 9, 2024 in MedPage Today, “Brain Worms Like RFK Jr.’s: Here’s What to Know,” Simon Groen, PhD, of the University of California Riverside, commented on RFK Jr.’s health issues. Dr. Groen said, “With the information we have thus far, it appears most likely that Kennedy’s condition was consistent with an infection by the pork tapeworm Taenia solium. It appears Kennedy traveled extensively in Africa, South America, and Asia in the past, and these regions have a much higher prevalence of infections than the U.S.” (It appears that Kennedy had an asymptomatic case of neurocysticercosis and therefore did not need treatment.)

But contrary to RFK Jr.’s claim,  a worm did not eat a portion of his brain. As any infectious diseases specialist could tell you, neurocysticercosis cysts don’t “eat” the brain. Instead, when the parasitic larvae reach the brain, they produce cysts that displace the surrounding tissue but don’t actually destroy it.

Two weeks after the May 8, 2024 New York Times article was published, Forbes published  an article by Steven Salzberg, “RFK Jr. Is Famous For Two Things, One of Them Is Dangerous.” (Steven Salzberg, PhD, is the Bloomberg Distinguished Professor of Biomedical Engineering, Computer Science, and Biostatistics at Johns Hopkins University.) In it, Salzberg acknowledges Kennedy’s positive claim for fame—his family, i.e., being the son of a former U.S, Senator and nephew of a former president. But Salzberg also calls out the “dangerous” side to RFK, Jr., and it isn’t the recent notoriety generated by Kennedy’s revelation of his diagnosis of neurocysticercosis.

Instead, it’s the enormously destructive impact Kennedy has had as an anti-vaxxer and the confusion and hesitancy he has sown among parents regarding childhood vaccines. In his article, Salzberg called Kennedy a “dangerous ideologue” and said, “[He] needs to take a hard look at the harm he’s causing to defenseless children, the elderly, and cancer patients, and anyone else with a week or compromised immune system.” And Salzberg warned that while RFK Jr.’s campaign for President is likely to fail, it “is likely to increase the spread of harmful anti-vaccine tropes.” Sadly, we don’t have a vaccine that protects against disinformation.

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Main Page images courtesy of Shuxian Hu, MD. Dr. Hu is a scientist in the Neuroimmunology Research Laboratory at the University of Minnesota.

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