Anisakis allergy: an update

Abstract Anisakis simplex is a worldwide-distributed nematode that infects consumers of raw or under-cooked fish. The clinical signs of anisakiasis depend on the place in the digestive tract where the larva is deposited. Symptoms develop as a result of an inflammatory condition occurring in the gastric wall mucosa when the larva enters it. Many asymptomatic subjects show high levels of specific IgE against A. simplex . It is often complicated to diagnose an allergy to A. simplex , due to the cross-reactivity with other allergens. It is even more difficult to diagnose it in infants than in adults. Positive skin tests to A. simplex usually correspond to subjects with positive results to other allergens. The high cross-reactivity between this and other parasites more prevalent in infants would be responsible for this confusion when an accurate diagnosis is to be obtained. The secretory–excretory antigen is more specific for recognising patients who actually have parasites. This antigen could be used for indicating parasitation in the differential diagnosis of this type of sensitisation. To prevent this condition, raw fish not previously frozen for 48 h, or fresh fish not cooked for at least 20 min above 60 °C, should not be consumed.