A 41-year-old woman in China who visited the hospital multiple times over the years complaining of mysterious stomach pains has finally been diagnosed and treated. It turns out, a 30-centimeter (foot-long) parasitic worm had set up camp in her digestive system, Fox News reports.
The unwelcome worm was found to belong to the Ascaris genus, a group of roundworms. These slimy freeloaders are the most common cause of parasitic worm infections in humans. The biggest to infect humans is Ascaris lumbricoides, sometimes called the “giant roundworm”, which grows up to 35 centimeters (14 inches) in length.
The worms spread from person to person in the form of eggs found in human poop. Poor hygiene and eating contaminated fruit and veg that hasn’t been washed, peeled, or cooked properly can lead to an infection. The disease is more common in areas with poor sanitation or where human feces are used as fertilizer.
The woman in question, referred to as Ms Yang, had to undergo surgery to remove the unpleasantly large parasite from her intestines. Her doctor, Dr Li Juan of the Second People’s Hospital of Haining in East China, also treated her family for potential Ascaris infections.
Speaking to AsiaWire, Dr Li said: “I couldn’t believe my eyes. Her intestines provided the ideal conditions for the parasite to grow, but it was still surprising to see a case in person.”

Life cycle of Ascaris: eggs are swallowed and worm larvae hatch in the intestine. They then travel via the blood to the lungs where they mature before being coughed up into the throat and swallowed. The larvae then develop into adult worms in the small intestine and their eggs pass out in feces. Aldona Griskeviciene/Shutterstock
Today, between 807 million and 1.2 billion people around the world are infected with A. lumbricoides. Humans can also become infected with Ascaris suum, a roundworm known to infect pigs. However, as the Centers for Disease Control and Prevention (CDC) note, pig roundworms are difficult to distinguish from human roundworms, so the number of people currently infected with A. suum is not known. Those who rear pigs or use raw pig manure as fertilizer are most at risk of becoming hosts to this particular species.
Since a parasite’s goal is to keep its host alive and functioning so it can siphon off its nutrients, people suffering from Ascaris infections often have no symptoms. If symptoms do occur, they can range from mild abdominal discomfort to fever, wheezing, and vomiting. According to the CDC, more severe Ascaris infections can lead to intestinal blockages and impaired growth in children.
Thankfully, the disease is treatable with antihelminthic medications like albendazole and mebendazole and preventable with good hygiene. Remember: always wash your hands thoroughly after touching soil, especially in areas where it might be contaminated with human (or pig) poop.