Hives or a swollen face after sushi or pickled herring, yet your fish allergy test was negative? The culprit may not be the fish at all. Anisakis is a small worm that lives in many sea fish, and its proteins can trigger IgE reactions. Our test checks for IgE to two Anisakis proteins, as part of 300 allergens and allergen components, right next to cod, herring, salmon and shellfish.
Anisakis simplex is a parasitic worm, a few centimetres long, whose larvae live in the gut and muscle of many sea fish and squid. It is common in fish from the North Sea and the Atlantic. Freezing and proper cooking kill the larvae, which is why raw herring in the Netherlands, for example, must be frozen before sale.
Killing the worm does not remove its proteins. Some of them, such as Ani s 1, are stable to heat and freezing. So a sensitised person can react to fish that was perfectly safe from an infection point of view.
Reactions people describe include hives, itching, swelling of the lips or face, stomach pain, vomiting and, in some cases, wheezing or a drop in blood pressure. They often start within a few hours of a fish meal. Eating live larvae in raw fish can also cause sudden, severe stomach pain, with or without allergic symptoms.
Swelling of the lips, tongue or throat, trouble breathing or feeling faint after eating is an emergency. Call 112 (EU) or your local emergency number. Do not wait for a test.
Classic fish allergy is mostly IgE to parvalbumin, a muscle protein of the fish itself. If that is negative and you still reacted to fish, Anisakis is one of the explanations researchers look at. The fish was the carrier, not the trigger.
The pattern matters. IgE to Ani s 1 points to Anisakis itself. IgE to Ani s 3 alone is harder to read: it is a tropomyosin, very similar to tropomyosins in shrimp, house dust mite and cockroach, so it often reflects sensitisation to those instead. Only a doctor or allergist can put the full picture together.
The lab measures IgE to two single Anisakis simplex proteins, as part of 300 allergens and allergen components. Fish (cod, herring, salmon and others), shellfish and house dust mite are on the same panel, so the fish, the parasite and the cross-reacting sources show up side by side. Each value gets a class from Negative to Very high on the lab report.
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One finger-prick sample checks IgE to 300 allergens and allergen components, from birch and peanut to cat and house dust mite. Post it to the lab, and about 5 days after it arrives you get a value for every one. Our plain-English guide shows you how to read them. €399 in total, €1.33 per allergen.
Yes. One known reason is Anisakis, a worm in many sea fish. Its proteins can trigger IgE reactions even when IgE to the fish itself is negative. A test that covers both the fish and Anisakis shows which one your blood recognises.
Freezing and thorough cooking kill the larvae, which prevents infection. Some Anisakis proteins survive heat and freezing, so sensitised people can still react. If you have reacted before, ask a doctor or allergist what applies to you.
Yes. Anisakis larvae are common in herring, mackerel, cod and other wild sea fish from the North Sea and Atlantic. That is why raw herring is frozen before sale in the Netherlands.
Ani s 3 is a tropomyosin, very similar to the tropomyosin in shrimp, mites and cockroach. IgE to it alone often reflects one of those. Show the whole result pattern to a doctor rather than reading one marker on its own.
