Here’s How Worms Get Into Your Brain And How To Prevent It

The internet blew up recently on reports that Robert F. Kennedy Jr. had a worm in his brain. Unfortunately, the medical problem that reportedly plagued RFK Jr., called neurocysticercosis, caused by larvae of the pork tapeworm, Taenia solium, is common worldwide. There are approximately 1,000 hospitalizations each year in the United States due to neurocysticercosis.

Unlike the fictional worms in “Star Trek2: Wrath of Khan,” which crawl into the brain through the ear, the eggs from tapeworms in this situation are ingested and the larvae they produce can reach not only the brain, but also multiple other organs of the body. Whether or not they cause a problem depends largely on where they end up.

How Does This Happen?

The phenomenon of cysticercosis occurs due to the interesting life cycle of the pork tapeworm. Humans can develop two different types of problems, depending on how they are infected. The first, which leads to a tapeworm, is when humans ingest raw or undercooked pork, called “measly pork,” that contains live larval cysts. The pork meat digests in the bowel, thus releasing the larvae, which attach to the wall of the small intestine and mature into a tapeworm.

In this situation, the human becomes a definitive host, because the tapeworm will spend its remaining days (up to two decades) living in the human intestine and producing thousands of eggs intermittently. Those eggs are passed in the feces and either go down the toilet, or if people don’t have toilets, the eggs can contaminate the local soil. The eggs can survive in soil for months, where they can be ingested by pigs. The eggs hatch in the pigs into larvae, which creates cysts in the muscles (i.e. creating measly pork) and other organs. The life cycle is completed when humans eat the measly pork.

The second method of human infection leads directly to cysticercosis, which is called neurocysticercosis when the brain is involved. In this situation, humans ingest food contaminated with human stool and tapeworm eggs. The food can be contaminated by food preparers who have a tapeworm and don’t wash their hands thoroughly after a bowel movement. Similarly, someone who already has a tapeworm can infect themselves by ingesting tapeworm eggs if they don’t wash their hands before eating. The eggs hatch into larvae inside the human and travel throughout the body. In this situation, the human becomes an intermediate host, and the larvae never leave the body. They also stay in place once they have landed somewhere.

There is a recently published story of a man who enjoyed eating undercooked bacon who developed increasing migraines, likely related to neurocysticercosis. It is presumed that he first developed a tapeworm from eating the undercooked pork and subsequently infected himself from tapeworm eggs from his own feces.

What Are The Manifestations Of Cysticercosis

Many people with cysticercosis are asymptomatic. Once the eggs are ingested, the larvae hatch in the bowel, penetrate the bowel wall and migrate through the blood to multiple parts of the body, frequently to areas that are immune “privileged,” such as the brain, eye or spinal cord, where the body has more difficulty mounting an immune response. Larvae can also be found in muscle and even the heart. CT scans of humans with a lot of larvae in their brains can look moth-eaten or like Swiss cheese. While alive, the larvae have a way of evading the immune system, so many individuals with cysticercosis can remain asymptomatic for several years.

Larvae in less risky parts of the body calcify when they die and may only be noticed incidentally on an imaging study, such as an X-ray or CT scan, taken for an unrelated purpose. However, when the larvae die, problems can occur due to the body’s inflammatory response, leading to local swelling. The inflammation can lead to seizures if the larvae are in the brain. This has caused significant morbidity, as neurocysticercosis is the No. 1 cause of seizures worldwide.

An Interesting Challenge

RFK Jr.’s story reminds me to emphasize that even if someone doesn’t have pork in their diet or who is very careful about their personal hygiene can still get neurocysticercosis. There have been cases without any identifiable risk factors, such as traveling to or growing up overseas in areas where cysticercosis is endemic. Upon investigating the cause, it turns out that individuals who prepared the patients’ food had tapeworms and were shedding tapeworm eggs in their stool. In the process of preparing the foods, it is likely the food preparer contaminated the food with tapeworm eggs. The important lesson here is: know the hygienic practices of whomever is making your food.

How Is Cysticercosis Treated?

If someone only has a tapeworm, they should be treated with one of several effective drugs, such as praziquantel or albendazole. Neurocysticercosis is more challenging. Treatment needs to be tailored to the individual patient, and is based on the location of the larvae and whether the larvae are alive. If someone is asymptomatic, it may be reasonable to leave well enough alone, reassure the patient and not treat them.

Anthelminthic (anti-worm) treatment may be needed for multiple larval cysts if they are still alive and causing a problem, possibly in conjunction with steroids to reduce inflammation and swelling. Antiepileptic medicines are used for patients with seizures. Surgery may be required if the larvae are in particularly problematic places, such as inside the ventricular spaces of the brain, because they could obstruct the flow of cerebrospinal fluid. Medications are not effective against dead, calcified larvae.

The consequences of pork tapeworm infections emphasizes key aspects of the importance of public health, as cysticercosis is a preventable infection. First, measures such as meat inspection and sanitation systems play a big role in preventing cysticercosis, which is why it occurs mostly in less developed areas of the world where these may be lacking. Second, this is just one of the many reasons you want to cook your meat thoroughly, especially pork. Third, your mother was right. It is important to wash your hands before eating, but this goes beyond our mothers’ and our own habits.

You have no doubt noticed those signs in the bathrooms of restaurants that say, “Workers are required to wash their hands before returning to work.” The hygienic practices of those who are making your food matters. Your health really does depend on it, because you don’t want larvae worming their way into your brain.