Doctors are warning people about the sushi and seafood because of a larval worm that can cause the illness, anisakis. The illness is caused by the parasitic anisakid nematodes in the fish or seafood. After ingesting the contaminated food, the worms can get into the wall of the stomach or intestines which can cause intense gastrointestinal pain, vomiting, and nausea. Complicated symptoms include digestive bleeding and peritonitis. Peritonitis is an inflammation of the abdomen inner wall.
Anisakiasis is caused by the parasite anisakis which live in fish and marine animals. If the parasite is consumed by humans in raw or undercooked seafood, it can cause an infection within the gastrointestinal tract. Anisakiasis happens in the world where the fish is eaten raw, salted, or lightly pickled such as Scandinavia, Japan, the Netherlands, Spain, and South America. Anisakis is slowly coming into the U.S. Symptoms of the infection include severe abdominal pain, malnutrition, and vomiting. If the larvae get into the large intestines, the symptoms start to mimic Crohn’s disease.
A study published in BMJ Case Reports examined a 32-year-old man who was healthy until he was admitted to his local hospital with “pain, vomiting, and [a] low-grade fever.” Joana Carmo, the study’s author and a physician at the Hospital of Egas Moniz in Portugal, stated that the man had a tender abdomen and increased white blood cells, indicating an infection, according to CNN.
Physicians at the hospital, after questioning the man’s diet, then completed an upper gastrointestinal endoscopy showing a “swollen intestinal membrane with a firmly attached parasite,” CNN reported. Using a “special net,” called the Roth net, they were able to capture the worm. The Roth net, a small plastic net, is used to remove colon polyps and parasites from the digestive tract. After removing the identified anisakis, the man began to feel better.
Carmo, speaking to CNN, said that it could infect “salmon, herring, cod, mackerel, squids, halibut, and red snapper.” Japanese physicians have reported “2,000 to 3,000” cases annually. In Spain, these numbers may be higher with the rest of the world catching up. The Centers for Disease Control and Prevention’s (CDC) spokeswoman, Amy Rowland, said, “Rare cases have been identified in the U.S.” Other researchers consider anisakiasis to be “underestimated and underdiagnosed.”
To fight the worm, the CDC recommends freezing fish to kill the parasite or thoroughly cooking the fish. According to the Japan Times, the Health, Labor, and Welfare Ministry issued a warning against the anisakis infection. Some, however, have stopped eating sushi, sashimi, and seafood altogether. Carmo said that trained sushi chefs could detect the worms because they are “grossly visible.”
By Cheryl Werber