Tokyo Food Safety Information Center » Tokyo Metropolitan Government food safety FAQ » What kind of food poisoning does the fish parasite Anisakis cause?
What kind of food poisoning does the fish parasite Anisakis cause?
What kind of food poisoning does the fish parasite Anisakis cause?
- Looking closely at fish fillets once, I saw little white worms moving around. Was this the parasite called Anisakis? What kind of symptoms would I experience if I had eaten it?
Anisakis is a parasite found in the organs and muscles of seafood like mackerel, Pacific saury, salmon, trout, and squid. When seafood which carries Anisakis is eaten raw or in a near raw sate, Anisakis enters the stomach and intestinal wall of human beings, causing gastroenteritis.
The most effective way to prevent Anisakis is to not eat seafood raw. If you are going to eat seafood raw, any Anisakis which has moved into the organs and muscle meat must be removed, but as this parasite is difficult to find, particular care is required. Another effective way is to completely freeze seafood down to its center (at -20° C for 24 hours or more), which kills Anisakis.
Characteristics of Anisakis
Anisakis in parasitized fish are in their larval form. They are two to three centimeters in length and are a semitransparent white color. Anisakis frequently appear in a spiral shape and are encased in a semi-transparent mucous membrane pouch (a cyst). In their adult form, Anisakis parasitizes marine mammals such as whales. In its larval form, Anisakis parasitizes sea life such as mackerel. Anisakis mainly resides in the organs of fish and other marine animals but may move into the muscle.
Are Anisakis food poisoning cases on the rise?
In line with the development of extensive distribution systems for fresh and live seafood, a great variety of seafood species have come to be eaten raw habitually, and this has resulted in a trend of increasing numbers of Anisakis food poisoning cases.
What are the symptoms?
Anisakis food poisoning frequently occurs within eight hours after eating parasitized seafood raw or near-raw and mainly causes intense stomach pain. This may also be accompanied by nausea and vomiting. If you suspect Anisakis food poisoning, consult with a doctor and a Public Health Center.
What kind of fish is it found in?
In recent years, cases of Anisakis food poisoning have been caused by (or are suspected to have been caused by) mackerel, salmon, trout, Pacific saury, skipjack tuna, and young Japanese amberjack. However, care must be taken with most fish species when eating them raw.
How can it be prevented?
Either by cooking, freezing, or removing the parasites.
◆Cooking: 60° C for at least 1 minute (until core is cooked)
◆Freezing: -20° C for at least 24 hours (until core is completely frozen)
◆Removing: Anisakis usually parasitizes the organs but can move into the meat, making it hard to find and completely remove. Accordingly, careful attention is required.
Cases of Anisakis food poisoning have occurred due to imperfect cooking, freezing, or removing. In addition, it is important to note that vinegar, soy sauce, wasabi, and other condiments as used normally will not kill Anisakis.