The proliferation of this parasite is difficult to quantify but the truth is that a good part of the fish from the seas around the Iberian Peninsula contains anisakis. Now, a genetic study developed by the Higher Center for Scientific Research (CSIC) shows that, in addition, it can combine and carry its own food allergens with those of other living beings.
The study, published in the journal BMC Genomics, has confirmed the existence of numerous gene sequences of food allergens, both their own and those of other living beings, in the genome of nematodes of the genus Anisakis. The results could help treat allergic reactions caused by this parasite.
Anisakiasis
The experts focused on the genetic study of two Anisakis species , A. simplex sensu stricto and A. pegreffii, and the hybrid between the two. These two species, along with a third called A. berlandi, are the main responsible for the condition known as anisakiasis, which is characterized by acute manifestations of epigastralgia (pain in the pit of the stomach), nausea, abdominal pain, diarrhea and allergic processes very severe.
“The species studied are not the only ones that have characteristic allergens, the hybrid larvae between the two carry their own battery of allergens, aspects that until now had not been taken into consideration and that will serve as epidemiological markers to evaluate the areas of incidence of anisakiasis” , explains Alfonso Navas, coordinator of the study.
Of the 509 allergens of food origin described to date, corresponding to fungi, animals and plants, the researchers have looked for homologues in the transcriptomes of the species analyzed in this study. The results show, with a similarity close to 100%, 937 protein sequences corresponding to 121 different allergens.
“This could explain the cases of sensitization or cross-reaction of anisakiasis patients against other sources of allergens, or of people who, being treated as allergic to other agents, manifest symptoms to these after being exposed to Anisakis. Everything indicates that these nematodes are an allergen bomb ”, adds Navas.
Not all of us are allergic
Anisakiasis has a notable incidence in the Spanish population. Fortunately, not all of us are allergic to the parasite, but this does not cause less interest in activities related to fishing and gastronomy.
Although fish infected with the larvae of this nematode are frozen to kill the parasite, people sensitized to Anisakis may show symptoms despite proper freezing.
The eradication of the parasite is impossible since the anisakis is an animal with a biological cycle. It cannot be considered a pest, but it is vital to control it.
According to Navas, “now we have a tool that will allow us to refine much more in the monitoring of the disease. Knowing which Anisakis species caused the reaction, their allergenic potential and the species of fish in which they were found will help treat Anisakis allergic reactions and the role of these nematodes in cross-reactions or in sensitization to other allergens. ”.
Reference: C. Llorens, SC Arcos, L. Robertson, R. Ramos, R. Futami, B. Soriano, S. Ciordia, M. Careche, M. González-Muñoz, Y. Jiménez-Ruiz, N. Carballeda-Sangiao , I. Moneo, JP Albar, M. Blaxter and A. Navas. Functional insights into the infective larval stage of Anisakis simplex ss, Anisakis pegreffii and their hybrids based on gene expression patterns. BMC Genomics 19: 592 DOI: 10.1186 / s12864- 018-4970-9
