Infection characteristics of Anisakis simplex (s.s.) in squids from NE Atlantic waters

Cephalopods have increasingly been reported as hosts of zoonotic parasites, notably Anisakis simplex (sensu stricto) (Nematoda: Anisakidae), which poses risks to human health through raw or undercooked seafood consumption. This study investigates the infection characteristics and anatomical distribution of A. simplex (s.s.) larvae in four commercially important squid species ( Loligo forbesii , Illex coindetii , Todarodes sagittatus and Todaropsis eblanae ) collected from Northeast Atlantic waters. A total of 425 specimens were examined for anisakid nematodes using the UV-press detection method (ISO 23036-1: 2021), and the larvae were identified morphologically and genetically by mtDNA cox 2 gene sequencing. Anisakis simplex (s.s.) was detected in all species, with T. sagittatus showing the highest prevalence (69.0%). Overall, larvae were predominantly found in the stomach and gonads, but notably also in the mantle tissue, particularly its posterior region adjacent to the digestive tract. The parasite was absent from the arms, tentacles and fins. A statistically significant positive correlation was observed between mantle length and Anisakis presence across all species. These findings confirm that squid, especially mesopelagic and demersal species, serve as important paratenic hosts of A. simplex (s.s.) in Northeast Atlantic waters, and highlight potential food safety risks associated with their consumption. The presence of larvae in mantle tissues emphasizes the need for enhanced surveillance, processing standards, and public awareness to mitigate zoonotic and allergenic risks. • Anisakis simplex (s.s.) was identified in 4 squid species from NE Atlantic waters • The larvae were found infecting viscera and mantle tissues in all 4 squid species • The highest Anisakis infection prevalence (69%) was found in Todarodes sagittatus • A positive correlation between mantle length and Anisakis presence was observed • Larval presence in squid mantle highlights potential anisakiasis risk in consumers