RFK Jr. had a brain worm. How do you get one and what are the symptoms?

(NEXSTAR) – Independent presidential candidate Robert F. Kennedy Jr. once had a parasite that caused him brain fog and memory loss, it was revealed Wednesday.

Kennedy, now 70, began noticing issues in 2010, complaining of short-term and longer-term memory loss. He was originally concerned he had a brain tumor, and when he got checked out, there was a dark spot visible on brain scans, the New York Times reported.

According to a 2012 deposition reviewed by the Times, Kennedy was told by a doctor the spot on the scan “was caused by a worm that got into my brain and ate a portion of it and then died.”

How common are parasites in the brain? What causes them?

When a person consumes tapeworm eggs – usually by eating contaminated food or drinking tainted water – the larvae can get into your organs and form cysts, the Centers for Disease Control and Prevention explains. The infection caused by the pork tapeworm, Taenia solium, is called cysticercosis. If the infection reaches your brain, it’s called neurocysticercosis.

The condition is rare in the U.S., according to Cleveland Clinic. There are an estimated 1,000 people hospitalized with neurocysticercosis every year, the CDC estimates. The most common states for hospitalization are New York, California, Texas, Oregon, and Illinois.

It’s more common in rural areas around the world with less rigorous sanitation and hygiene measures. The problems really arise in areas where pigs come into contact with human feces, the CDC says. Those pigs get the tapeworm, and then form cysts. Consuming raw or undercooked pork that’s contaminated can pass the infection to people.

Kennedy told the Times he’s not sure where he contracted the parasite, but suspects it may have happened while traveling.

What are the symptoms of the tapeworm infection?

The symptoms of pork tapeworm infection depend on where the cysts form. They can cause tender muscles when they form there, or blurry vision if they get into the eyes.

When they get into the brain, they can cause headaches and seizures. The infection is a “leading cause of adult onset epilepsy” around the world, the CDC says.

Neurocysticercosis can also cause “confusion, lack of attention to people and surroundings, difficulty with balance, excess fluid around the brain,” according to the agency. In severe cases, it can cause death.

Doctors who spoke with the Times said while it’s possible Kennedy suffered memory loss and brain fog as a result of the infection, it could also have been caused by mercury poisoning, which he was diagnosed with around the same time of the parasite discovery. Kennedy said he was eating a diet high in fish known to contain mercury.

What is the treatment?

These infections are typically treated with anti-parasitic medication. If drugs don’t work, a cyst may also need to be removed with surgery. In some cases, the problem resolves without medication or surgery.

Kennedy told the Times he has recovered from the memory loss and brain fog. He said the parasite didn’t require treatment.