Four years ago, doctors saw a British man who had been complaining of headaches after visiting China, South Korea, Japan and Thailand. They treated him for tuberculosis, but when he returned, he exhibited a host of more bizarre symptoms, CNN reported.

This time, in 2013, the man reported weakness in his legs and was also having seizures. After an examination, doctors determined the cause of his pain: Sparganosis, an infection that is rare outside of Asia and is caused by a parasite. In the case of the British patient, who was not named, the Spirometra tapeworm, which caused the infection, had burrowed into his brain and began feeding on his body.

Surgeons at Addenbrookes Hospital in Cambridge had to surgically remove the tapeworm from the man’s head because there is no known treatment for the condition.

According to CNN, only 300 infections of the Spirometra tapeworm were recorded between 1953 and 2013, and little is known about its populations because they live in rural areas of the world.
“These worms are pretty mysterious,” geneticist Hayley Bennett from the Wellcome Trust Sanger Institute, in Cambridge, whose team has sequenced the genome of the rare worm, told CNN. “We know it has a very complicated life cycle.”

What researchers do know is that the adult form of the Spirometra tapeworm only appears in the intestines of cats and dogs, but when the worms’ eggs are released through these animals’ feces, they can contaminate water and eventually infect humans.

Doctors predict that the worm took hold on the British patient when he was swimming in a lake and accidentally drank the water.

According to CNN, Bennett is studying worms to help improve future diagnoses and develop treatments. While the Spirometra tapeworm is rare, the pork species— known as Taenia Solium— is the more well-known species to infect the brain. That type of tapeworm can infect humans by way of eating infected pork or, in the larval form, by contact with the feces of an infected pig. This can cause neurocysticercosis, which may result in epilepsy once inside the brain. Self-infection can also occur due to poor hygiene, Helena Helmby, of the London School of Hygiene and Tropical Medicine, told CNN.

The World Health Organization (WHO) estimates that widespread numbers of pork tapeworms are present in Latin America, Africa and Asia.

Scientists noted that more tapeworm cases may occur in places like the United Kingdom as food import and export is increasing, thus elevating the risk of consuming infected goods.

“I’m confident there will be more of this in the future,” Gkrania-Klotsas told CNN. “People are getting infections without going anywhere.”

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