Presidential candidate Robert F Kennedy has told a deposition a parasitic worm "ate a portion" of his brain and then died, leading to a number of health issues.
A New York Times investigation this week revealed part of a 2012 deposition in which the independent US presidential candidate said he had suffered memory loss and mental fogginess.
His symptoms were so severe friends became concerned he may have a brain tumour.
Instead, a doctor believed he had a dead parasite in his brain, Mr Kennedy said.
'I have cognitive problems, clearly'
Scans of Mr Kennedy's brain revealed a dark spot – several doctors concluded he had a tumour, and he was scheduled for a procedure at Duke University Medical Center.
It was while packing for the trip that he received a call from a different doctor.
This doctor believed the dark spot "was caused by a worm that got into [his] brain and ate a portion of it and then died", Mr Kennedy said in a deposition given during divorce proceedings from his second wife.
Mr Kennedy was at the time arguing his earning ability had been diminished by cognitive issues.
The 70-year-old is the third of 11 children born to former-US attorney-general Robert F Kennedy and a nephew of former president John F Kennedy.
After the call, Mr Kennedy said he underwent a series of tests over the following weeks, which showed the dark spot on the scan had not changed.
He added he did not know the type of parasite but suspected he may have contracted it during a trip through South Asia.
Around the same time as he was diagnosed with the worm, he was also facing another health scare – mercury poisoning.
He said blood testing done after experiencing "severe brain fog" and memory issues found his mercury levels were 10 times higher than what the Environmental Protection Agency considered safe.
"I have cognitive problems, clearly," he said in the deposition quoted by the New York Times.
"I have short-term memory loss, and I have longer-term memory loss that affects me."
Mr Kennedy said he believed his diet had poisoned him.
"I loved tuna fish sandwiches … I ate them all the time," he told the outlet.
Mr Kennedy said he also suffers from atrial fibrillation, a heartbeat abnormality that puts him at higher risk of stroke or heart failure.
He said he had not had an episode in more than a decade, but had been hospitalised multiple times for the condition.
Presidential hopeful may have been infected with pork tapeworm
Medical experts have since suggested the most likely parasite to have infected Mr Kennedy was a pork tapeworm.
Mr Kennedy has not confirmed this.
University of Queensland professor of parasitology Malcolm Jones said becoming infected with the parasite could lead to a condition called "neurocysticercosis".
"Under most normal circumstances the pork tapeworm lives as an adult tapeworm within the small intestine of humans," he told the ABC.
"It reaches a length of around 4-7 metres and it's basically an egg producing factory, it produces thousands and thousands of eggs per day."
The eggs produced by the worm – around 30 microns or 0.03mm in diameter – leave the human body and infect pigs.
"[A cyst of eggs] sits in the pork meat, and … when people eat pork that's not cooked sufficiently, the parasites in the cyst inside the muscle can survive and become an adult tapeworm," said Professor Jones.
"However, there's an added problem. If a human should eat the eggs, the eggs will also become a cyst inside the body, sometimes inside the muscles.
"But in humans it seems to like to migrate to the brain … it happens really commonly, and there the larva develops from a tiny thing up into a cyst that's around 30mm in diameter.
"As it grows it feeds on host tissue and on nutrients carried in the blood, and it expands, and then probably by forcing out the normal tissue in the brain, it leads to a number of problems."
Neurocysticercosis has been labelled the leading cause of adult-onset epilepsy worldwide, according to the US Center for Disease Control (CDC).
"Most people who have had it will have headaches, but it's quite common for people to have eyesight problems, they may have seizures as well," Professor Jones said.
"The real problem is diagnosing this disease effectively. Medical people will use blood tests and they don't always work.
"One of the best ways of diagnosing it is through the more complex imaging scans, CT scans, they can be very good."
Once diagnosed, the CDC recommended several different anti-parasitic drugs as potential treatments.
[rfk]Health concerns 'a hilarious suggestion', campaign says
Mr Kennedy emerged as a wildcard candidate for the 2024 election, announcing his intention to run as an independent in October after abandoning a bid for Democratic nomination.
Since entering the race he has made a name for himself advocating anti-vaccination beliefs and promoting public health conspiracy theories.
He has denied accusations of promoting misinformation.
During his campaign he has also shared video of himself skiing with professional athletes and working out shirtless.
Amid questions about his health, his campaign issued a statement after the NYT investigation was released, saying health concerns were "a hilarious suggestion, given his competition".
"The issue was resolved more than 10 years ago, and he is in robust physical and mental health."
They declined a NYT request to provide Mr Kennedy's medical records.
A six page report released by the White House in February found President Joe Biden a "healthy, active, robust 81-year-old … who remains fit to successfully execute the duties of the presidency".
Former president Donald Trump has also released a statement from his doctor, which found the 77-year-old's physical exams "were well within the normal range" and "cognitive exams were exceptional".
However, debate over the age and competency of candidates has continued throughout the campaign.
A majority of Americans believe both Mr Biden and Mr Trump are too old for another term as president, according to a joint poll by ABC News US and market researcher Ipsos.
[Ipsos embed]Bruce Wolpe, a non-resident Senior Fellow at the University of Sydney's United States Studies Centre, said he didn't believe details about Mr Kennedy's health would impact the election outcome.
"I don't see any major political impact from this report on his medical condition, it's the Kennedy name that's driving his political campaign and that is unchanged," he said.
"A lot of people will filter this news out as strange but not important. Even if it is important, they've still seen RFK Jr in action and they're attracted to him, there's no way for that to affect his outcome.
"Another way of looking at it is [that] he chose a woman with no political experience to be his vice-president, that's ridiculous, but that hasn't changed his political trajectory.
"The key question remains not whether he has a worm on the brain but whether he has enough brains to get on enough ballots in enough states to potentially affect the outcome."
The 2024 US presidential election will be held on November 5.
