A 70-year-old cancer patient who underwent surgery to investigate blockages in his bile duct was found to have worms in his abdomen.
Five parasitic flatworms were found moving in the man's biliary tract, a series of tubes and ducts that carry digestive fluids from the liver to the intestines.
Chinese doctors who treated the man reported finding worms in his abdomen while performing the procedure, which eventually led to the discovery of a tumor in his colon.
The worm type was Clonorchis sinensis and comes from East Asia. These flatworms, which are not uncommon in certain areas of East Asia, typically infect a person's bile duct after consuming raw or undercooked freshwater fish or shrimp.
The worms, called Clonorchis sinensis, are endemic to Asia and typically infect people when they eat raw or undercooked fish
The worms were discovered accidentally when the man went to the hospital to undergo a cholangioscopy, in which doctors insert a camera either through the mouth or the skin to look for problems in the upper abdomen.
He was previously diagnosed with a type of cancer that develops in the large intestine (or large intestine), although the worms are believed to be unrelated.
According to the report in the New England Journal of Medicine, doctors extracted two of the five worms and determined they were C. sinensis, a type of worm that appears flat and leaf-shaped.
When a person eats fish and shrimp that contain an immature version of the parasite, it enters the bile duct, gallbladder or liver, where it matures into adult worms 15 to 20 millimeters long and three to four millimeters wide – about the size of a staple.
Most people who have the worms living in their biliary system — the name for the bile ducts as well as the liver and gallbladder that produce, store and secrete digestive juices such as bile — don't know they have them.
The disease is usually asymptomatic, but if left untreated it can lead to liver inflammation, gallstones and bile duct cancer.
According to a 2005 report in the journal Emerging Infectious Diseases, at least 600 million people worldwide are at risk of infection with parasitic worms.
However, the risk is highest in China, Korea and Vietnam, where the worms are endemic and cultural culinary practices often include eating raw or undercooked fish.
The doctors managed to remove the worms. They started the patient on praziquantel, a drug for parasitic infections, as well as chemotherapy for the localized cancer they discovered in his intestines.