How the parasite that presidential candidate Robert Kennedy Jr. said he contracted infects the brain

A little-known parasitic brain infection received a lot of attention Wednesday when presidential candidate Robert F. Kennedy Jr. said he once had it.

The disease, known as neurocysticercosis, is a brain infection linked to pig worm larvae. The disease is rare: it hospitalizes between 1,000 and 2,000 people a year in the United States.

Neurocysticercosis causes seizures, headaches, blindness, blurred vision, dizziness, psychosis, or memory loss. In some cases, it can even be lethal.

Infection usually follows a sequence of events: People eat raw or undercooked pork carrying a tapeworm or worm. They then pass tapeworm eggs in their feces and contaminate food or surfaces by not washing their hands. As a result, they or people around them who eat those foods or touch those surfaces may accidentally ingest tapeworm eggs.

Once ingested, the eggs hatch into larvae, which can move from the intestine to the brain. The larvae form fluid-filled sacs, or cysts, resembling small transparent balloons about a centimeter in diameter.

Eggs are “really sticky,” said Dr. Clinton White, a professor of infectious diseases at the University of Texas at Galveston. “They stick to hands and nails. I think that The hand-to-mouth route is an important route of transmission”.

In general, the disease is little known by health professionals, according to the Centers for Disease Control and Prevention (CDC), which considers neurocysticercosis a “neglected parasitic infection.”

Robert Kennedy Jr., during a Holbrook campaign event, Long Island, New York, on April 28, 2024.

“It's an important disease and it's very overlooked,” White explained.

This Wednesday, The New York Times reported that Kennedy, who is running for president as an independent, once suffered a parasitic brain infection.

Stefanie Spear, press secretary for the Kennedy campaign, said in a statement in response to the Times article: “Mr. Kennedy traveled extensively in Africa, South America and Asia in his work as an environmental advocate, and in one of those places contracted a parasite. The problem was resolved more than 10 years ago, and he is in solid physical and mental health.”

According to The New York Times, Kennedy said in a 2012 deposition that two years earlier, doctors had detected an abnormal spot on his brain amid symptoms of memory loss and brain fog. A doctor concluded that It had been caused by a worm that got into his brain and then he died, Kennedy told the newspaper.

NBC News could not immediately verify the details of the newspaper's report.

The newspaper also reported that Kennedy said he did not know what type of parasite it was. However, in an interview on the Internet radio show Pushing the Limits on Wednesday, Kennedy told host Brian Shapiro that the infection was neurocysticercosis and that the parasite “comes from eating undercooked pork.”

Among tapeworms, pork tapeworm is the most commonly associated with brain infections.

In March, doctors in Florida published a case study about a 52-year-old man who developed severe migraines from neurocysticercosis. The man had eaten undercooked bacon for most of her life, so doctors assumed she had contracted a tapeworm from the pig, shed its eggs and ingested them, causing the brain infection.

Neurocysticercosis larval cysts usually live in the brain for five to 10 years. When they begin to die, the immune system attacks them, and the inflammation can lead to epileptic seizures or life-threatening brain inflammation. Some cases of neurocysticercosis are asymptomatic.

In countries where the pork tapeworm is endemic, neurocysticercosis causes about 30% of all cases of epilepsy, according to the World Health Organization (WHO).

“It is an important neurological infection throughout the world”White said.

“The majority of cases in the United States are imported,” he added. “They occur in people who acquire the infection in endemic areas, especially in towns, say, in Mexico or Central America or South America.”

The infection is also endemic in sub-Saharan Africa and several parts of Asia.

White added that neurocysticercosis is beginning to be diagnosed more in the United States, most likely because doctors are becoming more aware of it.

“Perhaps it is the parasitic disease that causes the most problems in this country,” he said.

Although symptoms may go away on their own without any treatment, some patients may need anti-seizure medications or a combination of steroids and anti-parasitic drugs. In severe cases, patients they may need surgery to remove the cysts.