How Not to Get Brain-Eating Worms and Mercury Poisoning

Are you experiencing unexplained memory lapses or brain fog? Ever considered that you may have a parasite in your brain? That apparently was the startling diagnosis received by independent presidential candidate Robert F. Kennedy Jr. 14 years ago from one of the top neurologists in the US, according to a 2012 deposition which has recently been reviewed by The New York Times.

At the time, Kennedy was reportedly suffering from a constellation of neurological symptoms, which led concerned friends to believe he might have a brain tumor. Instead, it transpired that he had a parasitic infection. At around the same time, he said in the 2012 deposition and confirmed to the Times, he was also dealing with acute mercury poisoning.

The odds of dealing with both a brain parasite and mercury poisoning at the same time seem vanishingly rare. But just how rare is each condition? (Very.) And how can you avoid a similar fate? (Pretty easily.)

There are approximately two dozen parasites that we know can reach the brain, says Hany Elsheikha, a parasitology expert at the University of Nottingham, although this doesn’t always happen; many parasites are either cleared by the immune system or end up in the gut. They range from common species such as Toxoplasma gondi, which is believed to have infected around 11 percent of the population in the US over the age of six, to single-celled amoeba that can trigger fatal meningitis. It’s unclear exactly what sort of parasite might have lodged in RFK Jr.’s brain.

While parasite infections are more common than one might assume, they tend to settle elsewhere in the body. “Parasites don’t normally infect the brain, because it has a special anatomical structure which keeps it well protected,” Elsheikha says. “But sometimes they have a special affinity to the brain, and that person has a preexisting health condition or something going on in the background which makes them immunocompromised, and so the parasite seizes the opportunity.”

When parasites have the opportunity to reside in the brain or spinal cord, Elsheikha says, they usually take it, because the brain has a high metabolic activity, which means there is a plentiful supply of sugars on which the organism can feast. However, as apparently happened in Kennedy’s case, they can ultimately end up consuming brain tissue. Their presence can manifest in a number of symptoms; T. gondi has even been associated with a number of psychiatric conditions.

“It can take a while for a doctor to pinpoint the cause, because the symptoms aren’t specific,” Elsheikha says. “It can be an extremely debilitating long-term headache, anxiety, depression, lack of sleep, forgetfulness, some vomiting and nausea. One of the key signs that a parasite might be involved is if an excess amount of white blood cells called eosinophils show up on a blood test, as they are involved in the immune defense mechanisms against parasites.”

It’s not known how RFK Jr. contracted the parasite; he suggested to The New York Times that he may have picked it up in South Asia. The mercury poisoning, though, seems easier to pinpoint.

According to the US Environmental Protection Agency, almost all of us have at least trace amounts of methylmercury—the form of mercury we tend to encounter most—in our bodies due to its sheer prevalence in the environment. However, most of the time these levels are too low to result in any health problems.

While some of this can come from residing near power plants, as coal combustion releases a range of harmful pollutants including mercury, humans tend to ingest the chemical through consuming fish, says Awadhesh Jha, a toxicologist at the University of Plymouth. “A lot of industries are near the coastline, and most of their contaminants, including mercury, are discharged into the aquatic environment,” he says. “So fish accumulate more of them.”

While there is little information on the number of cases of mercury toxicity in the US each year, studies have shown that excessive mercury exposure can cause neurodevelopmental problems in children and expose adults to a greater risk of cardiovascular disease. In various national surveys across the US, people with an income of less than $20,000 per year, low education, and those who consume fish more than three times a week have been found to have the most mercury exposure.

Risks are highest when consuming larger fish, Jha says, because they accumulate greater concentrations of mercury in their bodies over time through eating smaller species. Because of this, both the EPA and the Food and Drug Administration advise pregnant women to avoid eating shark, swordfish, mackerel, or tilefish, as they may contain higher amounts of mercury, which could have an impact on the brain development of an unborn fetus.

For the rest of us, Jha says he advises a limit of no more than 170 grams per week of fish such as tuna or mackerel—approximately a single can of tuna—and in general no more than 350 grams per week of any fish or shellfish. Exceeding these limits on an occasional basis will likely have little impact, but doing so week-in, week-out will raise your risk of having higher mercury levels in your body.

The issue remains contentious among scientists, as eating a lot of fish also has known health benefits such as increasing intake of omega-3 fatty acids, which are protective against cardiovascular disease.

“Ultimately it depends on the person and how well they metabolize toxic substances,” Jha says. “It’s the genetic makeup of individuals which determines the toxicity of chemicals including mercury.”

Research has previously shown that mercury can affect the body in various ways, which can have an impact on immune function. Common signs of mercury poisoning are joint and muscle pain, weakness, fatigue, insomnia, and excessive sweating.

Anyone suffering from mercury poisoning can be treated through medicines called chelators, which remove mercury from the blood and keep it away from the brain and kidneys, but it’s a time-consuming process that can take weeks or months before symptoms improve.

“It will gradually decompose and then be metabolized and excreted, but it still depends if the mercury is bound by certain proteins and other molecules in the body,” says Jha. “If that’s the case, it might take longer to be eliminated from the body.”

RFK Jr. insists that he’s well past any ill effects from the dual maladies. “I offer to eat 5 more brain worms and still beat President Trump and President Biden in a debate,” the candidate tweeted Wednesday on X. “I feel confident of the result even with a six-worm handicap.”