Allergic reactions against anisakis larvae have increased in our country in recent months, which could be due to the fact that the average of larvae of anisakis present in blue whiting from the Atlantic that, according to the Spanish Society of Parasitology (SOCEPA), has multiplied by four this season.
Experts warn that in the years 2009 to 2011, among patients who presented symptoms suggestive of food allergy the percentage of those affected by sensitization to anisakis was between 21 and 29%, while that figure has risen to 39%. % during the first quarter of 2012.
For the disease to develop, anisakis larvae have to be alive, and some forms of cooking do not destroy the parasite
The specialists have verified, in addition, that the prevalence of anisakiasis differs significantly depending on the place of residence of the population analyzed; thus, in the Community of Madrid there are many more cases of people infected by the parasite than in Galicia, for example. The researchers attribute this fact to the different ways of preparing and consuming the fish, since the presence of the antibodies has been related to the intake of fresh fish and uncooked fish or cooked in microwaves.
For the disease to develop, anisakis larvae have to be alive, and some forms of cooking do not destroy the parasite. The main route of infection by anisakis in humans is, therefore, the intake of raw or undercooked fish (in vinegar, smoked, marinated, salted, or undercooked, grilled or in the microwave).
To prevent infection, it is best to abstain from consuming raw or undercooked fish, since the larvae die if the fish is subjected to a temperature of 60º for at least ten minutes. Another way to ensure that the fish is suitable for consumption is to freeze it at -20ºC for more than 24 hours. If you buy fish that has been frozen in the high seas, and you have also removed the viscera, it is very unlikely that it contains the parasite.