Uncooked fish can come with a nasty parasitical worm, doctors warn

Patient's severe pain, vomiting and fever disappeared after the worm was removed from his intestine

Ian Johnston
Science Correspondent
Saturday 13 May 2017 09:32 BST
Sushi containing uncooked fish can also come with a nasty parasite
Sushi containing uncooked fish can also come with a nasty parasite

Sushi containing uncooked fish can be infected with a worm-like parasite that attaches itself to the bowel, causing severe pain, vomiting and fever, doctors have warned in the BMJ journal.

A “previously healthy” man, 32, was admitted to hospital in Lisbon, Portugal, with symptoms that initially proved difficult to diagnose.

But, after doctors questioned him, he told them he had recently eaten sushi.

Not all sushi is made with raw fish, much of it is cooked. However, another popular Japanese form of cuisine, sashimi, is based on uncooked fish.

Putting a camera into his upper intestine led to the discovery of a parasite, the larvae of an anisakis nematode worm, attached to the inside of his bowel.

And it was this that had been causing the man “severe epigastric pain, vomiting and low-grade fever” and “moderate abdominal tenderness” for about a week, the doctors wrote.

The BMJ article said most cases described in the medical literature were from Japan because of the popularity of seafood.

“However, it has been increasingly recognised in Western countries,” the doctors wrote.

“Owing to changes in food habits, anisakiasis is a growing disease in Western countries, which should be suspected in patients with a history of ingestion of raw or uncooked fish.”

After the worm was removed using a special type of net, the man’s symptoms stopped immediately.

The doctors said the parasite was associated with a number of health problems.

“Patients can have allergic symptoms like angioedema, urticarial and anaphylaxis,” they wrote.

“Gastrointestinal symptoms include abdominal pain, nausea and vomiting and complications like digestive bleeding, bowel obstruction, perforation and peritonitis can also arise. Patients can also have a low-grade fever.

The UK sushi market is now worth about £69m a year.

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