After two years, the source of one Chinese man's severe abdominal pain and chronic anemia was finally found: a 20-foot-long beef tapeworm.

The case is now detailed in The New England Journal of Medicine, which was co-authored by the man’s attending doctor, Dr. Jian Li. In it, Li explains how his patient had been experiencing worsened pain, vomiting, generalized weakness and weight loss over the course of three days than he had in the years he’d been unwell. The man arrived at Li’s office with a tapeworm segment he found in his stool, confessing, too, that he liked to eat raw beef. Once Li confirmed tapeworm eggs in the man’s stool, he administered oral doses of an anti-parasitic drug, Praziquantel, as well as a diuretic drug called Mannitol. The patient discharged the massive tapeworm nearly three hours later.

Li’s official diagnosis was Taenia saginata infection — a result of eating raw or undercooked beef. T. saginata "attaches to the small intestine and can grow to be several meters in length," as long as 33 feet. "Although the tapeworm infection rate is quite high in the northwest and southwest districts of China, this was the first case of tapeworm seen in this part of China in 30 years," Li told Live Science.

Live Science cited cattle contract T. saginata when they feed on the eggs of the parasite; the eggs pass through human feces, and are especially rampant in poor areas of sanitation. Once the cattle eat the eggs, "they can hatch inside the cow, penetrate the intestinal wall and then circulate to the animal's muscles." The infection is then passed to humans whom eat the contaminated beef.

According to the Centers for Disease Control and Prevention (CDC), people with T. saginata may not know they have a tapeworm infection because symptoms are usually mild or non-existent. But like Li’s patient, symptoms can include digestive problems, including abdominal pain, loss of appetite, and weight loss. The CDC said the most visible sign, however, is the active passing of tapeworm segments.

Beef tapeworms tend to grow large than other tapeworms, producing more eggs than pork tapeworms, Live Science cited; though both are "neglected tropical diseases." Fortunately, this kind of tapeworm is rare in the U.S.

So, how is Li's patient now? After expelling the tapeworm, his weight and appetite returned to normal, he said. His love for raw beef, however, is likely long gone.

"It was physically, emotionally and financially exhausting for him," Li said.

To protect against beef tapeworms, the CDC recommends cooking meat at safe temperatures. This means going out and buying a proper food thermometer to use to measure the internal temperature of cooked meat. Per the USDA, whole cuts of meat (except for poultry) should be cooked to 145 degrees Fahrenheit and ground meat should be cooked to 160 degrees (also except for poultry).

Can't tell if abomdinal pain is just a stomachache or something more? Click here.

Source: Li J, Guo E. Taenia saginata Infestation. The New England Journal of Medicine. 2016.