Attention, sushi lovers: Be sure to tell your doctor what you've been eating if you develop sudden stomach cramps, diarrhea and vomiting.
That's the advice of the American College of Gastroenterology, which points to two reports from Japan that illustrate why. Raw and undercooked fish can contain larvae of a roundworm, called Anisakis. The larvae don't survive long in humans. But while present, they attach to the lining of the stomach and small intestine, where they can cause sudden abdominal pain, nausea, vomiting and diarrhea. The symptoms can sometimes look as if they stem from a small intestinal blockage or can be mistaken for appendicitis, stomach ulcers or peritonitis.
Fluid replacement and rest -- rather than more invasive treatments or medications -- usually relieve symptoms, which is why the college says it's important to let your doctor know your food preferences if these symptoms arise.
-- Sally Squires
Sushi bento. Eating raw fish could lead to severe intestinal problems. 
Studies presented at the 72nd Annual Meeting of the American College of Gastroenterology show that eating raw or undercooked fish, such as sushi or sashimi, can lead to severe intestinal problems caused by parasitic roundworms called anisakis.

Symptoms of the infestation include sudden abdominal pain, nausea, vomiting, and diarrhea, and can be severe enough to warrant a visit to the emergency room. One form of anisakiasis, the illness caused by the infestation, could be difficult to diagnose and could be misdiagnosed as appendicitis, peritonitis, or stomach ulcers, potentially leading to incorrect treatment.