Public health and prevention

Anisakidosis can easily be avoided by abstaining from raw or improperly prepared marine fish, but cultural food preferences are hard to change. Anisakis simplex larvae can live for weeks in seawater, but die quickly in strong brine. The Dutch experience with anisakidosis forced the authorities to impose regulations regarding salt, temperature, and storage time to kill larvae in herring. Larvae are killed by proper heating, 60-70°C, and deep-freezing

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at -20°C or below for some days. In continental Europe, herring are commonly marinated in brine and acetic acid; Karl et al. (1995) studied the effects of salt and acid on the survival time of Anisakis larvae. It is worth noting that dead larvae (i.e. frozen) fluoresce under UV light, and they can be removed by hand.

Anisakis simplex larvae occur in wild Atlantic marine salmon, but not in farmed salmon fed food pellets. Angot and Brasseur (1993) found no anisakid larvae in farmed salmon, and I have searched several thousand farmed salmon for parasites, without finding any A. simplex larvae. If fish are to be consumed raw, farmed marine Atlantic salmon should be the species of choice.

Some people are allergic to various foods, including fish. But do anisakid larvae also play a role in allergy? Recently, a number of papers indicate that. Pozo et al. (1996), reporting specific and intense immune response to A. simplex extract, concluded that A. simplex is able to induce anaphylactic reactions, and that allergy to it should be suspected in patients with allergic symptoms after ingestion of fish. Corres et al. (1996) reported on 28 cases of allergy caused by this nematode. Searching the web for Anisakis yields many more reports on allergic reactions, caused mainly by consuming raw or under-prepared fish and squids. Several websites give general advice on nematodes in fish, sea-food safety, and fish recipes.

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