Molecular epidemiology and risk factors for Anisakis simplex s.l. infection in blue whiting (Micromesistius poutassou) in a confluence zone of the Atlantic and Mediterranean: Differences between A. simplex s.s. and A. pegreffii.

Our study determined parameters of parasitization of Anisakis simplex s.l. in Micromesistius poutassou in a confluence zone of the Atlantic and Mediterranean, with a total prevalence of 82%. Also, in the three seasons analyzed, high prevalence's values were found, reaching 100% in spring; however mean intensity and abundance values were higher in winter. The use of molecular techniques to differentiate between Anisakis genotypes of the larvae characterized allowed obtaining values of 99.7% Anisakis simplex s.l. (50.1% A. simplex s.s., 42.9% A. pegreffii, 7.0% A. simplex s.s. - A. pegreffii hybrids) and 0.3% A. typica. The infections found in the fish were of both single and mixed species, in all the different possible combinations. The presence of A. simplex s.l. in the viscera varied according to genotype and season. Likewise, factors associated with the presence of the parasite in the ventral or dorsal musculature were different, where A. simplex s.s. proportion was double than that of A. pegreffii. The ecology of the two sibling species with regard to their location in fish and the influence of the season were different.