The accuracy of visual inspection for preventing risk of Anisakis spp. infection in unprocessed fish

The importance of the zoonoses caused by L3 Anisakidae larvae lies in the repercussion that this parasite exerts on food safety and quality. EU legislation recommends fish operators to do visual inspection of the whole fish abdominal cavity and gut to control the risk of visible parasites, thus ensuring that no contaminated fish reach the consumers. The accuracy of the above visual inspection method should fall on a well-tested statistical significance between the number of observable parasites in the abdominal cavity and the number of parasites in the edible part of the fish (i.e., musculature). The aim of this study was to analyze this statistical significance, and the efficacy of the washing practice to remove Anisakis spp. from gut. To carry out this work, 322 fresh individuals of Micromesistius poutassou and 230 of Scomber scombrus were necropsied within 12 h and 48 h post-capture. Then, descriptive statistics, correlation and regression analyses were used to evaluate the significant statistical relationship between the number of anisakid larvae found in the gut and musculature of both fish species. Additionally, livers and gonads of 25 fresh specimens of Merluccius merluccius were vigorously washed under tap water, and examined under stereomicroscope looking for Anisakis spp. larvae. Results evidenced the low efficiency of visual inspection of gut parasites as a commonly recommended method for predicting nematode larvae in the flesh of fish. Therefore, a direct-invasive inspection of musculature is stressed as the only criteria with scientific merit for accurately detecting contaminated fishes by anisakids. Moreover, fresh European hake liver and gonads showed at least one larva remained inside the tissue after washing vigorously under tap water. Results suggested that critical control points at Hazard Analysis Critical Control Point (HACCP) programmes should be reviewed to improve the risk of anisakid-induced allergies and gastrointestinal anisakiasis among consumers.