Pork tapeworms infected a man's brain causing migraines

By Stephanie Srakocic | Fact-checked by Davi Sherman
Published March 15, 2024

Key Takeaways

  • A man with a history of migraines had parasitic larvae growing in his brain.

  • Taenia solium infections are rare in the US, and the man had no history of travel to areas with high infection rates.

  • The source of the man’s infection was a history of eating undercooked bacon.

An unnamed 52-year-old man from the US who had a history of migraines sought treatment after his symptoms worsened and his regular medications weren’t helping. The man and his doctors were surprised when imaging revealed he had an infection of Taenia solium, a pork tapeworm, growing in his brain. T. solium normally infects pigs but can sometimes spread to humans who consume undercooked pork products.[][]

T. solium infections are rare in the US and other countries with strict food safety standards. Higher concentrations of infections are found in Latin America, Eastern Europe, sub-Saharan Africa, India, and Asia, especially in communities where raw or undercooked pork is eaten. Travel to and immigration from these regions has spread the parasite farther in recent years, but it is still uncommon in the US. The Center for Disease Control and Prevention estimates that there are fewer than 1,000 new taeniasis cases in the US each year.[]  

The case report revealed that the man recently diagnosed in the US had not recently traveled to high-risk areas However, he did tell doctors that he enjoyed eating bacon that was undercooked and “soft.” 

Consuming undercooked contaminated pork products is the primary way of contracting T. solium. Once the parasite is ingested, a few outcomes can occur. Most commonly, consuming T. solium eggs or larvae leads to taeniasis, in which small sacs, or cysts, form in the intestines. The parasite can also cause a condition called cysticercosis, which occurs when cysts develop inside a different tissue, such as muscle or the brain. When these cysts grow in the nervous system, the condition is called neurocysticercosis.[][]

Neurocysticercosis most often causes headaches and seizures. The severity and specificity of symptoms depend on which structures and tissues in the brain are affected by parasitic cystic growth. The  unnamed man had a history of migraines but sought care after four months of experiencing pain that was more severe and occurring more often than his baseline. Doctors ordered a CT scan and became concerned when they spotted multiple cysts growing near the nerve fibers deep in his brain.[]

Doctors admitted the man to a hospital, where an MRI revealed cysts in the front and middle part of the outer layer of his brain, as well as brain swelling. This confirmed a  diagnosis of neurocysticercosis. Treatment with antiparasitic and anti-inflammatory medications brought the infection under control.[] 

Food safety and parasites 

Foodborne parasitic infections in the US are relatively rare. However, they do occur. The authors of the case report urged physicians to consider neurocysticercosis as a diagnosis “when an existing neuropathological condition displays a change in presentation or requires a change in therapeutic management, even without obvious risk factors.”[] 

Additionally, despite their rarity, foodborne infections are a common health concern. Outbreaks of infections such as E. coli are often featured prominently in the news. On social media platforms like TikTok, videos with millions of views discuss parasites in foods—and how to prevent inadvertently consuming them. 

Fortunately, there are easy and actionable steps you can provide to patients who express fears about parasites and food safety. 

“The good news is that in the United States, our production systems protect animals from disease so that we see much less risk of transmission of these organisms,” says Kalmia Kniel, PhD, Professor and Associate Chair in the University of Delaware’s Department of Animal and Food Sciences.  She says people can protect themselves by preparing their meat well and taking care to clean their hands and kitchen. “It is critical to cook meats appropriately and use a meat thermometer...Also, wash your hands after handling meats, throw away the packaging from meat, and be cautious not to get the drippings or moisture from the package on your kitchen countertop,” she says.

Dr. Kniel gives specific recommendations for handling and consuming different types of meat. 

“Consumers who hunt and eat game animals should be more cautious, as these animals are at higher risk since they forage for food and exist in free-range lifestyles, where they are more likely to come in[to] contact with parasites. I recommend that these meats be fully cooked and checked with a meat thermometer,” Dr. Kniel says. “There are parasites that infect fish as well. Some of these are visible to the naked eye, including small and large worms or larvae; these can be removed. Fish parasites are killed by freezing. Freezing a fish for several days at -4 degrees Fahrenheit or cooking it to 140 degrees Fahrenheit can kill parasites.”   

As for risks associated with consuming undercooked pork products—as seen in the case report—Dr. Kniel tells MDLinx

“The US pork industry has done very well to reduce this risk with a historic program known as the Trichinae-free certification program. [Additionally,] there is some data to suggest that salt brine solutions that may be injected into hams can have an antiparasitic effect, so these products should still be cooked to the appropriate temperature but may be less risky.”

For more detailed cooking advice, you can point patients toward this chart of safe minimum internal food temperatures, produced by the United States Department of Agriculture.[]

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