Independent presidential candidate Robert F. Kennedy Jr. said doctors found a dead, parasitic worm in his brain in 2010, the candidate’s campaign confirmed to Spectrum News on Wednesday.

The 70-year-old Kennedy family scion told The New York Times he had recovered from symptoms connected to the parasite consuming part of his brain -- including memory loss and mental fogginess -- and that it did not require treatment.

“Mr. Kennedy traveled extensively in Africa, South America, and Asia in his work as an environmental advocate, and in one of those locations contracted a parasite,” Kennedy’s campaign press secretary Stefanie Spear said in a statement to Spectrum News. “The issue was resolved more than 10 years ago, and he is in robust physical and mental health. Questioning Mr. Kennedy’s health is a hilarious suggestion, given his competition.”

Kennedy has centered much of his campaign on his conspiratorial views on health and medicine, and frequently contrasts his relative youth and personal physique with his main rivals: 77-year-old former President Donald Trump and 81-year-old President Joe Biden. The longtime antivaccine crusader spent years promoting misinformation about the risks of vaccines, including promoting the long disproven, false conspiracy theory that linked childhood vaccines to autism.

As he began his anti-vaccine activism in the early 2000s, one of his central focuses was on thimerosal, a mercury-based preservative that was safely used in vaccines for decades before being largely phased out by 2001, according to the Centers for Disease Control and Prevention. Speaking with the Times, Kennedy said he also suffered from mercury poisoning from eating too much fish around the same time as contracting the parasite. 

Mercury can be found in high levels in fish like tuna and perch, which Kennedy said he was consuming a lot of at the time. Mercury poisoning can cause brain damage, according to the Environmental Protection Agency. Kennedy told the Times he had tests done at the time that found he had 10 times the amount of mercury in his blood than the EPA deems safe.

“I loved tuna fish sandwiches. I ate them all the time,” he told the Times.

Kennedy began his presidential campaign in the Democratic primary before switching to an independent bid. His campaign has been working on getting him and his running mate, lawyer and philanthropist Nicole Shanahan, on the ballot in all 50 states. So far, they say they have gotten ballot access in California, Hawaii, Idaho, Iowa, Nebraska, Nevada, New Hampshire and North Carolina.

Both the Trump campaign and the Biden campaign have upped their attacks on Kennedy in recent weeks, fearful he will siphon support from their respective candidates in November. The Democratic National Committee put up a billboard in Las Vegas on Wednesday portraying Kennedy as a “spoiler” candidate who will split the anti-Trump vote and allow the former president to win.

“Look, RFK is falling very low. He's not a serious candidate,” Trump said last week outside the Manhattan criminal courtroom where he’s on trial. “The numbers that he’s taking away, they say will be against Biden. I don’t know, it could be a little bit against me, but I don’t see him as a factor.”

Beyond the brain worm and the mercury poisoning, Kennedy has a long history of health issues dating back decades. Most notably, his voice sounds strained and raspy due to a condition called spasmodic dysphonia that affects his vocal chords.

“In 1996, when I was 42-years-old, I was struck with… spasmodic dysphonia and it makes my voice tremble,” Kennedy said in a NewsNation town hall last year. He said he went to a specialist in Japan six months earlier for a “novel surgery” he said helped strengthen his voice, later telling an interviewer that he had titanium implanted in between his vocal chords.

And in 2001, he was hospitalized for an irregular heartbeat, according to media reports at the time. The Times reported on Wednesday that Kennedy said in a 2012 deposition that he had been hospitalized three more times between September 2011 and early 2012 to have his heart treated, including once when he said doctors used a defibrillator to shock his heart back into a regular rhythm.

The Times also reported that Kennedy said in the deposition, which Spectrum News has not reviewed, that he contracted hepatitis C while using intravenous drugs as a younger man, but that he received treatment and no longer suffered any health impacts.