Robert F. Kennedy Jr. had a brain worm. He also allegedly ate dog (he says it was a goat) and he wanted to skin a road-kill baby bear to eat it before discarding the remains in Central Park. This is all juicy red meat (sic) to a parasitologist like me.
Where to begin?
The New York Times uncovered the worm story from a 2012 deposition by Robert F. Kennedy Jr. He had sought medical attention for memory loss and brain-fog. If you’ve heard RFK speak, you know that he also suffers from spasmodic dysphonia. In the course of a CT-scan looking for brain anomalies, they found the calcified remains caused by a worm. RFK Jr told the New York Times that there were no long-lasting consequences.
“A worm … got into my brain and ate a portion of it and then died,” he said.
There are quite a few parasites that can get into your brain. I’ll first dispense with what it was not, and with the notion that anything “ate a portion” of RFK’s brain.
Only the amoeba Naegleria fowleri will actually eat your brain. Primary amebic meningoencephalitis (PAM) is rare, afflicting fewer than 10 people annually in the US. Featured in the two-part “Euphoria” episode of House, it’s almost always fatal. In fact, jumping into a warm pond is a great way to get PAM, because it forces the amoeba-infested water way up past your sinuses to the vomeronasal organ through which Naegleria can access your brain.
Toxoplasma gondii is adept at crossing the blood-brain barrier. It’s even being studied as a way to deliver therapeutics to the brain. Most people will never know they are infected. (With the exception of mothers who end up birthing children with deformities). Mice, not humans, are the intended hosts. When the brains of mice are infected with Toxoplasma they fail to avoid the smell of cats, and the mice engage in more risky foraging behaviours. It’s perfect for completion of the parasite life cycle in which cats eat mice. Cat has parasite in gut -> cat poops out cysts -> mouse accidentally ingests cysts -> intermediate parasite stages get into mouse brain -> mouse loses fear of cats -> cat eats mouse -> one complete cycle. Repeat. It’s a probabilistic algorithm.
People (with cats) get infected with toxoplasmosis too (kitty litter). And there’s plenty of evidence that toxoplasmosis is not as “asymptomatic” as once thought. It’s more than just cat-people/hoarders not noticing the overwhelming smell of cat urine. Infection with Toxoplasma alters expression of dopaminergic genes. This is associated with an increased frequency of everything from road rage to schizophrenia. Toxoplasma infection prevalence is also a consistent, positive predictor of entrepreneurial activity.
Tapeworms
Toxoplasma wouldn’t show up on a brain scan, though. But the cystic larval stages of two tapeworms would: cysticercosis from the larval stages of the pork tapeworm, and hydatidosis from the larval stages of a dog tapeworm. Yes, a dog tapeworm. I sure hope RFK Jr didn’t eat dog.
Taenia solium, the pork tapeworm is not a pig tapeworm, it’s a human tapeworm. The only host for the adult worm is humans. Full stop. Cystic larval stages in brain and muscle stages result from something eating human poop, or eating something that has been contaminated by human poop. Pigs rooting around in human poop get the larval stages in their muscles and brains. We eat their muscles because pork is really very tasty. The cysts are digested open in your stomach and small intestine, the larvae mature, and we get the adult tapeworms in our large intestines.
But if we eat something that’s been contaminated by an infected person’s fecal matter, there’s nothing preventing our getting the larval stages in our muscles and brains. Cysticercosis (pron: sis-ti-sir-koe-sis) usually results from a food handler who has a tapeworm in their gut. But you can easily autoinfect yourself. It’s as simple as this: you happen to have the adult tapeworm in your own gut, which you got from eating undercooked pork, you poop, you wipe (I expect), you fail to wash your hands, hand goes to mouth, worm goes to brain. You just gave yourself neurocysticercosis (pron: nure-oh-sis-ti-sir-koe-sis).
Human behavior is at the core of an enormous amount of disease burden. These and other parasitic multitudes have spent millennia learning our human behaviors. They know it better than we do. But we can get in front of the parasites. The “intended” outcome of RFK’s brain worms was for them to be eaten by another human when that zombie ate RFK’s brain. They failed at that (so far). Since we don’t eat human brains with any regularity, this is a parasite that remains a serious cause of dementia in the developing world, but which could be totally eradicated with just hand washing.
Bayesian statistics: how many brain worms?
OK. So what’s the probability that someone has neurocysticercosis? This is what we call a prior in Bayesian statistics. The prior in the US is 0.2 to 0.6 cases per 100,000 general population. But, if you also know someone is Hispanic, the prior changes to 1.5–5.8 cases per 100,000. In Bayesian statistics you can take into account a wide range of conditional probabilities – the probability of a storm off the coast of Sicily, the probability of a tornado in a storm, and the probability that a superyacht has a 240 mast height – all very Bayesian.
None of that really matters in the case of RFK’s brain worm. At this point we know RFK had one, so the prior is 100%. What’s the probability that he had more than one? Cysticercosis follows a Poisson probability, not a Normal one. This is why we invented General-IZED linear models. General Linear Models assume normality, where the expectation about an average is the same plus or minus something. Generalized linear models can use other distributions. In the Poisson, when the mean is low, the less-than-average are more concentrated than larger numbers. It’s asymmetrical.
So, given that we know RFK Jr actually had at least one, and given that among those who have them, the average (λ in Poisson notation) is 3, we can say that the probability that RFK Jr had more than one is 80%. There’s also the prior probability (37%) of any larval cyst calcifying and showing up on a brain scan. Most don’t. So, we can even say that the posterior probability of his having had at least 3 is maximal because he had at least one calcify in his brain to be found by a brain scan.
Based on Bayesian posterior probabilities, it is essentially certain that RFK Jr had more than one worm in his brain. Calculating the posterior probability of each possible number of worms is different, and maybe less interesting.
I want to be clear that up to now there’s been no evidence that neurocysticercosis from Taenia solium causes spasmodic dysphonia nor the avoidance of common-sense behaviours to prevent disease transmission… like hand washing… or masks… and vaccines…
Nor is there evidence that neurocysticercosis would cause someone to write a book (or two) encouraging others to do likewise so as to increase transmission of parasites in the general population for example. But that would be ingenious of the parasites.
Dog meat
RFK Jr told a friend to “try the dog” in Korea. Mind you, that actually does look like a goat in Patagonia. Nonetheless, one of the risks associated with eating dog meat is a different brain worm. Hydatid disease is transmitted from dogs to other mammals. The life cycle of Echinococcus tapeworm species includes a(ny) mammal intermediate host with larval stages encysted in various tissues. The adult tapeworm is in the gut of a dog. Infection typically happens to a rabbit, mouse, or sheep after ingesting eggs that have dog poop contaminating the grass they are eating, for example. Humans get infected through contact with dog feces. So, there’s no reason why unhygienically prepared dog meat (in Korea or Patagonia) wouldn’t suffice for transmission.
That said, human hydatidosis is not most common where people eat dogs, but rather where dogs are allowed to eat the offal of slaughtered livestock. Presently that’s Iran where hundreds of people (and thousands of sheep and camels) are afflicted. It’s more often in the liver than the brain.
Human hydatidosis was a huge public health issue in 19th century Iceland. Most people in Iceland knew someone who had died from it. The solution (as argued for carbon) was a high tax on all dogs, and a ban on keeping a dog without permission.
While dogs were integral to Icelandic farm life, they were banned in Reykjavik. And although the disease disappeared from Iceland by about 1900, that ban remained in place throughout the 20th century. It was quite a scandal in the 1980s when Minister of Finance Albert Guðmundsson was found to be illegally keeping a dog in Reykjavik.
The Bear
You can easily get brain worms from eating bear meat due to yet another parasite, Trichinella. Bear meat figures prominently in the history of human trichinosis/trichinellosis even though infections have more often come from pork. The parasite is a nematode (a.k.a. “threadworm”). Eating undercooked meat riddled with the encysted larvae leads to adults in your gut. Female worms give live birth to their larvae, which then migrate around your body to encyst in all of your tissues – brain included.
Yul Brynner (“The King and I”) won a $125,000 settlement from the Plaza Hotel in 1973. He was diagnosed with trichinosis and blamed pork spare-ribs from Trader Vic’s. You really only have to cook meat to 145 F to kill the worms instantaneously. You can even go for 135 F if you cook it sous vide for an hour. It’s fun to see the alarm on your guests’ faces when served rare pork tenderloin.
In addition to wild boar, almost all bear meat is infected with Trichinella. The ill-fated 1897 Swedish Andrée expedition tried to reach the North Pole by balloon. For 3 months, stranded on the island of Kvitøya, they shot and ate polar bear. It has long been speculated that they died of trichinellosis. There are still periodic outbreaks of human trichinosis especially from Northern climes.
It’s not too hard to find bear meat, and bear-meat induced trichinosis in Brynner’s home country, Russia. Just last year 6 people were hospitalized in Trans-Baikal having contracted severe cases from undercooked bear. A 2008 outbreak in Humboldt county California was caused by eating bear meat at a community event where more than 3/4 of the attendees fell ill. And dried meat (jerky) from a black bear caused a recent outbreak in Northern Ontario .
Central nervous system (brain) encystment of the larvae occurs in about 10% of cases, and is fatal if sufficiently severe. Dysphonia is common in less severe cases.