Anisakis – The parasite hiding in your sushi

Do you love having some fresh, delicious sushi for dinner? Well, that makes two of us. Unfortunately, and quoting an article from the Italian Journal of Food Safety, “This food is not free from health risks such as ingestion of pathogenic bacteria or parasite”.

Indeed, as the popularity of these traditional Japanese dishes keeps rising so do related foodborne diseases, which include potential sushi-related infections from Vibrio Species, Listeria monocytogenes, Salmonella spp., Bacillus Cereus and the classic example, anisakiasis, a human parasitic infection of the gastrointestinal tract caused by the consumption of raw or undercooked fish or squid containing larvae of the nematode Anisakis simplex.

The first case of human infection by a member of the family Anisakidae was reported more than 50 years ago in The Netherlands by Van Thiel. One of the most recent cases, a 32-year-old Portuguese man had his case published in the British Medical Journal.

Having severe abdominal pain and fever for a week alongside with vomiting, he set off alarm bells after telling doctors that he had eaten sushi recently. It turns out he had a nematode worm parasite Anisakis simplex attached to his gut, which was removed, allowing the symptoms to go away and a full recovery for the patient.

Anisakis simplex found in the gut of a 32-year-old Portuguese man. Source: British Medical Journal.
Anisakis simplex found in the gut of a 32-year-old Portuguese man. Source: British Medical Journal

It truly makes us think twice about those Nigiri and Temaki we were planning on having. However, the Anisakis larvae is known to lose its infectivity after freezing at −20°C (or lower) for 24 hours (or longer), so the FDA recommends freezing the fish for at least 1 week or blast freezing (−35°C or below) for at least 15 h, which is good news for us sushi lovers. Regarding the bacteria aspect, “a good rice acidification (pH of the rice must be less than 4.6) and the maintaining of cold chain during preparation and storage are also essential to obtain products of good microbiological status”.

Other references:

Japanese Journal of Infectious Diseases

Anisakis simplex: from Obscure Infectious Worm to Inducer of Immune Hypersensitivity

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5 comments

  1. Hi Ana,
    Good to see you posting again.

    i too like to have my sushi and the best sushi is with the freshest fish i.e. there is no freezing process. So, I am curious, how common are these Anisakis infections? Hoping that they are not very common!

    Liked by 1 person

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