Live worm leaves bad taste in Japanese sushi-lover's mouth

A Japanese woman who complained of a twitchy tonsil received a shock when a doctor diagnosed that a live worm had burrowed into the organ to the rear of her mouth.

The 25-year-old, who has not been named, had eaten an assortment of sashimi five days before she visited her doctor complaining of pain and irritation in her throat, according to a case study published in the July edition of the American Journal of Tropical Medicine and Hygiene.

A medical team at St Luke's International Hospital in Tokyo was able to remove the worm from her tonsils with tweezers. They reported that it was still alive and shedding an outer layer of skin.

Identified as a nematode roundworm – one of a number of parasites that can find their way into human hosts who consume raw fish or meat – the worm was black and measured nearly 1.5 inches long.

The case study, by three Japanese scientists, reported that the patient's symptoms "rapidly improved" after the worm had been removed, and that blood tests were normal.

Nematode roundworms can cause gastric, intestinal, ectopic and allergic diseases in hosts, but are more commonly found in the stomach or intestinal tract after being swallowed, the study said.

An infection in the mouth is "rare", the authors said, but is generally known as "tingling throat syndrome".

The report added that there have been hundreds of documented cases of worm infections in countries in which seafood is consumed raw, primarily Japan and in South America.

It also warned that cases have "markedly increased worldwide" as sushi and sashimi become more popular in other areas. Infections are more likely if chefs are not trained in how to prepare raw fish dishes.