The growing popularity of sushi could be behind a rise in parasitic infections, doctors have warned.
Fans of the Japanese treat have been told to be wary of the dangers of ingesting parasites from raw and undercooked fish.
It comes after doctors in Portugal treated a 32-year-old man who was found to have larvae from a parasite attached to his gut lining.
Writing in the British Medical Journal, the experts said he had been suffering stomach pain, vomiting and fever for a week.
A blood test showed mild inflammation, and the area below his ribs was found to be tender.
But it was only when the man said he had recently eaten sushi that doctors suspected he might have anisakiasis.
Anisakiasis is a parasitic disease caused by anisakid nematodes (worms) that can invade the stomach wall or intestine of humans. It occurs when infected larvae are ingested from undercooked or raw fish or squid.
Doctors performed an endoscopy on the man, inserting a long tube with a camera into the stomach.
They found the larvae of a worm-like parasite firmly attached to an area of swollen and inflamed gut lining.
A special kind of net was used to remove the larvae "and the patient's symptoms resolved immediately", the team from a central Lisbon hospital said.
They added that most of cases of anisakiasis to date had been reported in Japan but warned: "However, it has been increasingly recognised in Western countries."
