Parasites could be lurking in your sushi, doctors warn

Story highlights

A 32-year-old man developed severe upper gut pain, vomiting and fever after eating sushi

Anisakiasis infection is caused by a parasite in some raw or undercooked seafood

Japan sees about 2,000 to 3,000 cases of anisakiasis infections each year

CNN  — 

Anisakiasis, an illness caused by eating parasite-contaminated fish or seafood, is on the rise in Western countries where eating sushi and other raw or undercooked fish and seafood dishes has gained popularity, according to a report published Thursday in BMJ Case Reports.

The authors draw a portrait of the illness from the experience of a previously healthy 32-year-old man who developed severe upper gut pain, vomiting and fever that lasted a week before he entered the hospital.

Dr. Joana Carmo, lead author and a physician in the gastroenterology department of the Hospital of Egas Moniz in Lisbon, Portugal, and her co-authors say a physical examination indicated tenderness in the abdomen, while the lab results showed an increase in white blood cells, which is a typical sign of infection.

During an interview, the man said he had recently eaten sushi.

Fishing out a parasite

Based on this dietary information, his doctors performed an upper gastrointestinal endoscopy: a non-surgical examination of the digestive tract, using a flexible tube with a light and camera on the end. This inner vision revealed a swollen intestinal membrane with a firmly attached parasite, its end penetrating the stomach.

The doctors removed the larval worm with a special net.