Raw fish consumption in Portugal: Commonly consumed fish species and associated risk factors for anisakiosis

Abstract

Foodborne parasitic zoonoses from fish and shellfish products are of significant health concern. Anisakiosis is an important fish-borne zoonosis caused by nematodes of the genus Anisakis. Humans are infected through consumption of raw or undercooked fish or cephalopods containing Anisakis spp. Third stage larvae. Infection can result in both gastrointestinal and allergic symptoms. Globalization has resulted in a growth in demand for raw or undercooked food, and this may increase the population at risk of anisakiosis. Our study's main aim was to investigate the risk of anisakiosis from the five fish species most frequently consumed raw or undercooked in Portugal, as identified by a previous study. In addition, a study was carried out to identify the fish species most commonly used in raw fish dishes in Asian restaurants serving Japanese food in the Porto district. The results of this study were incorporated into the risk investigation. The 5 fish species most commonly eaten raw were salmon, tuna, cod, hake and sardines. This was similar to our findings in the restaurant survey, which identified salmon and tuna as the most popular fish served in raw dishes. It also identified nigiri, sashimi and temaki as the most popular raw fish dishes. After examination of the production practices and parasite prevalence for each of the five fish species, we concluded that the main risk groups for anisakiosis were consumers who prepare raw or lightly processed fish dishes at home, if they are unaware of methods to prevent anisakiosis. Some cooked fish dishes may also present a risk, lightly grilled wild salmon or sardines have the potential to contain viable Anisakis larvae. We identified a need for further studies, to establish the level of consumption of wild salmon and wild tuna, and a large-scale study to examine the level of sensitization to Anisakis within the Portuguese population. Our findings highlight the need for more consumer education campaigns regarding the risks associated with raw fish consumption, and prevention methods for anisakiosis. In addition, our study emphasises the need for a more standardized approach to inspection measures within the fish supply chain, to prevent products contaminated with parasites reaching the market.