Doctors discovered a rare tapeworm living in a man's brain for four years.

According to New York Post, the 4-inch ribbon-shaped parasite burrowed 2 inches through the man's head from one side to the other, causing intense pain and migraines in the last couple of years.

"The tapeworm causes sparganosis, an inflammation of body tissues that can cause seizures, memory loss and headaches when it occurs in the brain," New York Post reports.

The 50-year-old man of Chinese descent and living in East Anglia, UK first sought medical help from London's St. Thomas' Hospital in 2008 after "suffering from headaches, seizures, memory loss and complaining that his sense of smell had changed," The Telegraph reports.

Not knowing the real problem, the man was tested for other diseases including HIV, lime disease, and syphilis, said The Telegraph. In 2012, a "10 cm ribbon-shaped larval worm" was discovered in the man's brain tissue.

"An MRI scan showed a cluster of what appeared to be lesions in his brain, but specialists were baffled as to the cause. And they were more surprised to find that the lesions kept moving. Brain scans over the next four years showed that the anomaly had travelled at least 5cm through the tissue," The Telegraph further stated.

After diagnosis, surgeons removed the tapeworm, identified to be of the rare species Spirometra erinaceieuropaei, using drugs. The man has now completely recovered, The Telegraph noted. This is the first case of such parasite in the UK. It has occurred only 300 times worldwide since 1953.

It is unknown how the patient got the parasite, but The Guardian reports that the Chinese man often returns to his home country. The tapeworm was probably picked up by a using a raw frog poultice, which is a popular remedy in China for sore eyes, and by "accidently consuming tiny infected crustaceans from lakes, eating raw meat from reptiles and amphibians."

According to a report from The Guardian, the parasitic worm has no mouth and may have absorbed nutrients from the man's brain through its body.

"This worm is quite mysterious and we don't know everything about what species it can infect or how. Humans are a rare and accidental host for this particular worm. It remains as a larva throughout the infection. We know from the genome that the worm has fatty acid binding proteins that might help it scavenge fatty acids and energy from its environment, which may be one the mechanisms for how it gets its food," Dr. Hayley Bennet stated, as quoted by The Guardian.

The news outlet reports that Dr. Effrossyni Gkrania-Klotsas of the Addenbrooke's NHS Trust said the tapeworm's occurrence in the UK is highly unexpected, but people travelling abroad can transfer the parasite to other countries.

"We can now diagnose sparganosis using MRI scans, but this does not give us the information we need to identify the exact tapeworm species and its vulnerabilities," the doctor told The Guardian.