US presidential candidate Robert F Kennedy Jr, known to many as RFK Jr, hit headlines this week after a decade-old deposition emerged in which he talked about “a worm that got into my brain and ate a portion of it and then died.” No prizes for guessing that brain worms are not a great thing to have, but you might be surprised/horrified to learn just how common these parasites are. 

Now that RFK Jr is tweeting that he’d happily “eat five more brain worms” and still fancy his chances in the 2024 electoral race, here’s all you need to know about where these parasites come from, and how you get infected.

What type of parasite did RFK Jr have?

In a deposition from 2012, recently reviewed by the New York Times, Kennedy describes neurological symptoms that he had as far back as 2010. After experiencing memory issues and brain fog, he reportedly sought advice from medical experts, who noted a “dark spot” on scans of his brain.

A number of medics concluded that this was a sign of a tumor, but even as he was preparing to undergo surgery, Kennedy received a call from a doctor with a different opinion: that the dark spot on his brain was the corpse of a parasitic worm.

The New York Times has since spoken to several independent experts who say the symptoms would fit with a diagnosis of a pork tapeworm, although all were speaking in a general capacity and have not directly dealt with RFK Jr’s case.

What are pork tapeworms?

The pork tapeworm (Taenia solium) is a cestode worm responsible for the human diseases taeniasis and cysticercosis. Three species of Taenia worms can infect humans, but T. solium is the most devastating by far.

Taeniasis occurs when someone eats undercooked pork from an infected pig containing worm larvae, called cysticerci. Over the course of a couple of months, the worms attach to the inside of the small intestine and mature. Adult T. solium can reach lengths of up to 8 meters (26 feet) – you’d think it couldn’t get much worse, but with this particular tapeworm, the adult is actually the least of your problems.

As the 20-foot unwelcome visitor happily chills in your intestines, sometimes for years, it develops up to 1,000 segments called proglottids, and each of these can contain a staggering 50,000 eggs. These eggs are passed in feces. Like other diseases that can pass via the fecal-oral route – i.e. via food contaminated by traces of fecal matter or poor hand hygiene – it’s possible to then reinfect yourself, or infect someone else, with the parasite’s eggs.

This is far more serious than the initial tapeworm infection. The eggs hatch in the intestine, and the resulting oncospheres can pass through the intestinal wall and reach lots of other areas of the body – including the brain. There they develop into cysticerci, and that’s how you get the disease known as cysticercosis, or neurocysticercosis if it affects the brain. 

The T. solium lifecycle is one of the more complex among human parasitic diseases, but it’s this ability for reinfection with one’s own tapeworm eggs that makes the pork tapeworm so much more dangerous than the similar beef tapeworm, for example.

How common are pork tapeworms?

According to the Centers for Disease Control and Prevention (CDC), neurocysticercosis caused by the pork tapeworm is considered a Neglected Parasitic Infection in the US, with around 1,000 new hospitalizations each year, and is a leading cause of adult-onset epilepsy worldwide. This is a global parasite found across places where pork is commonly eaten, mainly in rural regions where pigs and humans may come into close contact.

Higher rates of taeniasis from T. solium have been recorded in rural communities in Latin America, Eastern Europe, sub-Saharan Africa, India, and Asia. Both taeniasis and cysticercosis are thought to be underreported. Studies have found high rates of infection among communities in Madagascar, Eastern and Southern Africa, and parts of China, among others, with researchers calling for better surveillance and monitoring around the world.

In the US, taeniasis is most frequently seen in people who have immigrated from Latin America.

Cysticercosis arises most commonly in people who already have T. solium taeniasis, via the process of autoinfection described above. However, it’s possible to develop cysticercosis through contamination – for example, eating food prepared by someone with taeniaisis if scrupulous hand hygiene has not been observed – even if you have never consumed undercooked pork and have not personally been exposed to the adult tapeworm.

Can pork tapeworms be prevented or treated?

Both taeniasis and cysticercosis caused by T. solium are preventable. Your best defense is to make sure that any pork products are cooked thoroughly before consumption. 

The CDC cites the recommendations of the US Department of Agriculture when it comes to preparing pork. Whole cuts should be cooked to a minimum internal temperature of 63°C (145°F) and left to rest for three minutes. Ground pork should be cooked to a minimum of 71°C (160°F) but does not require resting. A meat thermometer will be your best friend here.

A 2020 study also looked at other cooking methods, and found that for boiled pork dishes, cooking for 10 minutes at 80°C (176°F) was sufficient to kill T. solium larvae. At 50°C (122°F), a cooking duration of over 40 minutes was required. They concluded that the majority of boiled pork dishes would meet safety requirements, but suggested that deep-frying pork could be an issue due to the shorter cooking times involved. 

T. solium larvae can also be thwarted by freezing meat at -20°C (-4°F) – slightly colder than most commercial freezers) – for one to three days.

Other control methods targeting the pigs themselves, such as attempting to detect the parasite before animals are slaughtered and efforts to keep pigs and humans apart, have had varying degrees of success.

Once someone is infected with T. solium, there are some treatment options, but these can be costly and may not be accessible. The most common medication used for taeniasis is called praziquantel, which is taken orally. However, both praziquantel and another drug that can be used, albendazole, may not be suitable for people with cysticercosis, as they’ve been linked with possible seizures. 

With neurocysticercosis, treatment starts by tackling symptoms like seizures and brain swelling before targeting the parasites themselves. Antiparasitic treatments can also make symptoms worse at first, so steroids may be given at the same time to help dampen down the inflammatory response.

The brain damage caused by extensive neurocysticercosis can be permanent. In RFK Jr’s case though, the New York Times reports that his memory loss may be down to a different condition he reportedly had at the time, one with less terrestrial origins. The report explains how he was diagnosed with mercury poisoning, caused by eating excessive amounts of fish. 

That’s not one you can prevent by cooking it, unfortunately.

All “explainer” articles are confirmed by fact checkers to be correct at time of publishing. Text, images, and links may be edited, removed, or added to at a later date to keep information current.  

The content of this article is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of qualified health providers with questions you may have regarding medical conditions.