Occurrence of nematodes of the genus Anisakis in Mediterranean and Atlantic fish marketed in Sardinia

Anisakiasis is a gastrointestinal fishborne zoonosis caused by the ingestion of third stage larvae of the genus Anisakis. Between January and December 2013, 1112 specimens of four commercial fish species (Engraulis encrasicolus, Merluccius merluccius, Scomber colias and Trachurus mediterraneus) marketed in Sardinia (Italy) were examined for Anisakis sp. The overall prevalence of Anisakis spp larvae was 39.9%, all morphologically identified as Type I. Scomber colias showed the highest prevalence (100%), followed by M. merluccius (Atlantic 91.0%, Mediterranean 71.2%), T. mediterraneus (32.7%) and E. encrasicolus (25.9%). All the larvae found in Mediterranean hosts were genetically identified as Anisakis pegreffii, whereas 90.0% of the larvae found in the Atlantic M. merluccius belonged to Anisakis simplex sensu stricto and 10.0% to A. pegreffii. The mean abundance of Anisakis sp. larvae was positively correlated with fish size in E. encrasicolus, Atlantic M. merluccius and local M. merluccius. The prevalence of infection was greater in the body cavity (37.9%) than in the edible muscle (9.4%). However, 1.8% of the examined fish were infected exclusively in the muscle. Therefore, the risk associated to the consumption of raw or undercooked fishery products poses the need of measures such as visual inspection and preventive treatments to guarantee consumers’ health.