Here’s what to know about brain worms from doctors who’ve treated them

Yes, it’s possible to have a worm living in your brain — in fact, it’s far more common than you might think, according to area doctors who specialize in tropical disease medicine.

brain worms became a topic of public fascination Wednesday after the New York times reported that presidential candidate Robert F. kennedy Jr. was mistakenly diagnosed with a brain tumor after scans picked up abnormalities that turned out to be “caused by a worm that got into my brain and ate a portion of it and then died,” he reportedly said in a 2012 deposition reviewed by the New York times.

the boston globe spoke with area doctors about RFk Jr.’s claims. Here’s what you need to know.

What kind of worm did RFK Jr. have in his brain? And how did it get there?

though RFk Jr. has not publicly disclosed the parasite involved, three doctors told the globe the most likely culprit was t. solium, a parasite that can infect the brain and cause a condition called cysticercosis. In most cases, someone eats food contaminated with parasite eggs, the eggs hatch, and “sort of migrate through the body, ending up in muscles or in the brain,” said Dr. David Hamer, a professor of global health and medicine at the boston University School of Public Health, who also directs a travel clinic at boston Medical Center.

Other less common parasites are also a possibility. they include a flatworm contracted through wading into or swimming in some fresh water sources, predominantly in brazil, but also in Africa and Asia. It usually infects the intestines, the liver, and the bladder, and its eggs can also migrate to the brain. Another type of worm is passed on by infected slugs, which shed the parasite in slime that sometimes gets onto vegetables and can make its way to the brain after people eat the vegetables. It can cause meningitis and has led to outbreaks in China, Southeast Asia, and Hawaii. the most fatal is a brain-eating amoeba that people can, in very rare cases, contract in warm fresh water. It’s ingested through the nose and often leads to encephalitis that is almost always fatal. In 2021, a child in texas died after contracting a brain-eating amoeba at a splash pad near Dallas.

How common are these parasites?

t. solium is a “common parasite.” the other parasites are “rare zebras,” said Dr. Edward t. Ryan, director of global infectious diseases at Massachusetts general Hospital — which is why both Ryan and Hamer suspect t. solium was the cause of RFk Jr.’s troubles. Ryan, who specializes in tropical diseases, said he treats “scores” of patients every year who have been infected by the parasite. bMC’s Hamer said he has treated about 20 patients suffering from cysticercosis over the course of his 30-year career.

the infection is more common in Latin America, where it is believed to be among the most common causes of seizures.

Can you get a brain worm from eating uncooked pork?

An individual can contract t. solium by consuming undercooked pork infected with the tapeworm. but a second step is needed for the parasite to take up residence in the brain. Usually after an individual consumes infected meat, the adult tapeworm takes up residence inside their intestines. It then lays eggs that are “shed in the stool of the infected individual,” Hamer said. that stool then becomes the means by which the larval stage of the tapeworm finds a new host.

In one famous case, an outbreak occurred in an Ashkenazi Jewish community in Manhattan, most of whom did not eat pork. the infection was eventually traced back to a Latin American domestic worker in one of the households, who had failed to wash their hands prior to preparing produce.

“Somebody that has the adult tapeworm inside of their intestine can have minimal symptoms, if any at all,” Ryan said. “but if their hands get contaminated with some of the eggs that get passed and then they prep a meal for somebody, the little eggs can hatch inside the intestine of that second person. the larvae can then penetrate the intestinal wall, go through the blood system, and set up shop at all different spots in the body.”

Possible destinations include the muscles, the eye, or the brain.

What are the symptoms of a brain worm?

Once in the brain, the parasite forms protective cysts and releases a stew of chemicals designed to disguise its presence from the immune system. this allows most worms to go undetected during their life cycle. Some grow at an alarming rate, eventually reaching the size of a pea, a grape, or even larger.

It’s when the parasite’s life cycle ends, after five to 10 years, that symptoms usually start. Once the parasite dies and stops releasing chemicals, the immune system detects its presence and attacks. this can cause the brain to swell, which can cause severe headaches, interfere with normal motor function, and trigger seizures. the swelling usually recedes after a couple of weeks, leaving behind a calcified scar, and the condition rarely causes long-term damage.

but it’s usually during this “acute” phase that individuals seek medical attention and undergo testing. Some individuals have multiple cysts, and the imaging can reveal the presence of other parasites that have not yet died.

“Some people’s brains almost look like Swiss cheese with lots of holes, and there can be a fair amount of inflammation,” Hamer said.

Medical treatment, when warranted, usually consists of a two-drug antiparasitic regimen and steroids to reduce the inflammation that can occur when the parasites die.

Can parasites eat your brain?

Hookworms in the belly can drink human blood. And some species of amoeba can swim up into the holes at the top of the nose, enter the brain, and eatneural tissue. but flesh-eating parasites are extremely rare, Ryan said.