Back in 2010, years before he announced his current presidential campaign, Robert F. Kennedy Jr. was told the memory loss and mental fogginess he was experiencing might have been the result of a brain tumor, according to a report by the New York Times.
The author and trial lawyer had consulted neurologists who found a dark spot in his brain scans. Ultimately a doctor from New York-Presbyterian Hospital suggested his condition “was caused by a worm that got into my brain and ate a portion of it and then died,” Kennedy said in a 2012 deposition reviewed by the Times.
The Kennedy campaign confirmed to U.S. News Wednesday that Kennedy did have a parasite, but said it no longer impacts his health. “The issue was resolved more than 10 years ago, and he is in robust physical and mental health,” says press secretary Stefanie Spear. “Questioning Mr. Kennedy’s health is a hilarious suggestion, given his competition.”
U.S. News caught up with Dr. Peter Hotez, professor of pediatrics and molecular virology and microbiology at Baylor College of Medicine, to learn more about brain parasites, including how they get into their human hosts and the symptoms they cause.
While Kennedy’s press secretary suggested the presidential candidate picked up the worm during his travels outside the United States, Hotez, who is also dean of the National School of Tropical Medicine at Baylor, says there are two brain parasites that are “quite common” in America as well. “These diseases are not rare,” he tells U.S. News.
The following interview has been edited for length and clarity:
How does someone end up with a parasite or worm in their brain?
One of the two diseases is called toxocariasis and the other one is called neurocysticercosis and they’re transmitted slightly differently.
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In the case of toxocariasis, these are diseases contracted ultimately from stray dogs and cats. What happens is those stray dogs and cats are infected with an intestinal roundworm called toxocara and that roundworm is producing thousands and thousands of eggs that contaminate the soil. The eggs are ubiquitous in the soil and around sandboxes or playgrounds or just in the dirt, and kids – or adults – get contaminated with the dirt containing eggs, swallow those eggs. And then the eggs hatch in the gut and they give rise to larvae, worm larvae, that migrate through the lungs. They can cause wheezing and asthma and they migrate through the brain to cause cognitive disturbances, developmental delays and seizures. And it’s actually quite common in the United States, and people don’t know about it.
Now the other one is called neurocysticercosis. It’s typically a household member who’s got a tapeworm that is in the gastrointestinal tract and segments of the worm are dropping off that contain the eggs and then the eggs are released into the environment. Then the eggs get dispersed, you swallow the eggs, and the same kind of thing happens.
Once that larval tapeworm is in the brain, while it’s alive, it’s actually almost not even recognized by our immune system or inflammatory system. It’s living but it’s silent. And it’s not really feeding on brain tissue … but it’s living there. And as that worm exceeds this natural lifespan in the brain, then it dies and as it’s dying it loses its ability to camouflage itself from the host immune system. And you start seeing inflammation around it. And that’s what triggers the seizures. So neurocysticercosis basically produces a seizure disorder.
How do parasites migrate to the brain?
The [toxocara] larvae that hatch out of the eggs in the gastrointestinal tract penetrate the intestinal lining and eventually get swept through the blood circulation and probably get carried to the brain through the blood. And the larvae are just a few millimeters in length, but they can cause mechanical damage and they also elicit inflammation. And that’s been shown to lead to kids’ developmental delays and seizures as well as in adults can cause cognitive disturbances.
The [tapeworm] larvae again can go through the gut lining, and then make their way through the blood circulation to the brain.
What are the symptoms of having a parasite in your brain?
Neurocysticercosis can be clinically silent for years. And then oftentimes the first presentation is having a seizure. With toxocara, it’s oftentimes more subtle: developmental delays, cognitive disturbances, sometimes seizures. And there you have to have a high index of suspicion to think about doing the blood test for it.
Can you take steps to avoid these two parasites?
One is to be cognizant of your surroundings and know if you’re living in an area that’s known to be endemic. Clearly, handwashing is going to be very important as a preventative step. In the case of toxocariasis, it’s controlling the stray dog and cat problem and/or deworming stray dogs and cats.
What areas are endemic?
(For toxocara), Brazil is a big, big-time problem. It’s more in the Southern United States. Although, we even found it in the Bronx as well.
Neurocysticercosis, we see it in the Southern United States and Texas, Southern California even. And typically it’s (tied to) having another person in the home with this adult tapeworm.
What is the treatment for brain parasites?
Toxocariasis is treated through several days of a specific drug that kills the worm called albendazole. For just neurocysticercosis, you need a much longer course of albendazole.
(With neurocysticercosis), eventually that worm dies and it becomes calcified. But the problem is, it can still continue to trigger seizures. So oftentimes, people who have neurocysticercosis have to not only go on anticonvulsants, but they sometimes require going on treatment for anticonvulsants for years afterwards, even though it’s a dead worm.
Can these infections impair cognitive function?
Both toxocariasis and neurocysticercosis cause cognitive impairments. The evidence for neurocysticercosis is not as clear-cut.
And how long would cognitive impairment last?
You know, it’s not as well-studied. There’s so much focus on the seizures, that people only started recently looking at cognitive impairment with neurocysticercosis. (With toxocariasis) it could be for years. And then the next question is, could it produce permanent deficits? And the answer is potentially.
What else do I need to know?
First of all, these diseases are underdiagnosed. If a physician or pediatrician or internist has someone coming in with cognitive disturbances and developmental delays, they don’t think about doing a test for toxocara. So it tends to get underdiagnosed. We need improved diagnostics.
