Seafood safety and food-borne zoonoses from fish: Examining the risk of Anisakis in the Portuguese Population and Consumer Risk Perceptions of Fish Consumption

Evaluating fatty acid profiles in anisakid nematode parasites and adjacent tissue of European hake (Merluccius merluccius): a first insight into local host-parasite lipid dynamics

Parasitism in fish is a widespread and ecologically significant phenomenon, affecting fish in both wild and aquaculture environments. Comprehending parasitism is essential for managing fish populations, protecting fish health, and preventing human exposure to zoonotic parasites. Understanding lipid dynamics between parasitic organisms and their hosts is crucial for elucidating host-parasite interactions. Although the third larval (L3) stage of anisakid larvae is not a developing stage, and therefore not as dependent on the host for the acquisition of nutrients, there are hints of interplay between parasites and fish hosts, also in terms of lipid content. This study aimed to characterize for the first time the fatty acid profiles of anisakid nematode parasites and adjacent tissue in the European hake (Merluccius merluccius) in order to shed some light on these intricate relationships. Fatty acid analysis revealed significant differences in the percentages of individual fatty acids between anisakid nematodes and adjacent European hake tissue. Anisakids presented a higher content in stearic (18:0), vaccenic (18:1n-7), and linoleic (18:2n-6) acids, while in turn, the belly flap tissue of the fish presented significantly higher contents in palmitic (16:0) and especially docosahexaenoic acid (22:6n-3) than the parasite. These differences suggest unique lipid metabolic pathways between parasite and fish, and that parasitism and the possible acquisition of lipids from the host (hake) do not profoundly shape the fatty acid profile of the parasites. Furthermore, the distinct fatty acid signatures described for parasites and hosts may serve as baselines to follow possible changes in the ecological statuses of both species and even to appraise the nutritional features of European hake when affected by parasitism. This study provides valuable insights into the lipid dynamics within host-parasite systems and underscores the importance of further research to unravel the complexities of these interactions.

Detection and Characterization of Visceral Anisakid Nematodes in Blue Whiting from Portuguese Waters

This study employs molecular detection techniques, including conventional PCR and Sanger sequencing, to investigate the prevalence, species composition and public health implications of Anisakid nematodes in blue whiting (Micromesistius poutassou) caught off the Portuguese coast. With Portugal's high fish consumption rates and increasing preference for raw or undercooked seafood, the risk of parasitic infections, particularly anisakidosis, is rising. Fifty blue whiting fish were examined, showing a 100% infection rate with Anisakid larvae. Molecular analysis identified 68.1% of the larvae as Anisakis simplex, 18.1% as Anisakis pegreffii, and 13.8% as Hysterothylacium aduncum, marking the first report of H. aduncum in blue whiting in Portugal. Phylogenetic analysis based on the internal transcribed spacer (ITS) 1, 5.8S ribosomal RNA and ITS-2 confirmed the species classification. Notably, 42.9% of the fish were infected with multiple Anisakid species, increasing the risk of allergenic sensitization. Statistical analysis showed no significant correlation between fish width and parasitic load, and a weak negative correlation was found between fish length and parasitic load. The study contributes to food safety by integrating molecular tools that enable rapid and accurate species identification, offering new insights into the detection of biological contaminants in seafood. These findings are significant considering the rising trend in raw seafood consumption, underscoring the urgent need for enhanced detection strategies and broader parasite monitoring programs to mitigate public health risks. The high prevalence of parasitized fish highlights the necessity for the implementation of safe cooking practices to reduce the risk of anisakidosis. Further research into the allergenic potential of Hysterothylacium spp. and the ecological factors influencing this nematode distribution is recommended.

Assessing Portuguese health risks: Anisakiks parasite in Atlantic chub mackerel (Scomber colias) sold in Portuguese markets

Anisakiosis is a significant zoonotic disease caused by parasitic nematodes of the Anisakis genus. It can be contracted by humans through the consumption of raw or undercooked fish contaminated with the parasite, leading to gastrointestinal and allergic symptoms. While anisakiosis is not frequently documented in Portugal, the presence of allergic reactions to Anisakis in Spain suggests ongoing exposure in the Iberian Peninsula. To address this concern, the Interdisciplinary Centre of Marine and Environmental Research in Porto, Portugal, in collaboration with the Biology Centre of Czech Academy of Sciences in Ceske Budejovice, Czech Republic, has proposed a project entitled 'Assessing Portuguese Health Risks: Anisakis Parasite in Atlantic Chub Mackerel (Scomber colias) Sold in Portuguese Markets' under the European Food Risk Assessment Fellowship Programme. The primary objective of the project is to gather valuable epidemiological data on the host, Atlantic chub mackerel (S. colias) and the parasitic nematode (Anisakis spp.) with the focus on assessing contamination levels and evaluating potential health risks associated with anisakiosis in the Portuguese population. By conducting this research, the project aims to contribute to the understanding of anisakiosis and its impact on public health in Portugal. Investigation of the presence of the Anisakis parasite in Atlantic chub mackerel sold in Portuguese markets will provide crucial insights into the risks associated with consuming raw or undercooked fish. Ultimately, our findings will aid in the development of preventive measures and guidelines to ensure the well-being of the Portuguese population.

Basophil Activation Test in the Diagnosis of Anisakis Allergy: An Observational Study from an Area of High Seafood Consumption in Italy

The rising popularity of undercooked or raw seafood containing larvae of the Anisakis parasite has led to issues of public health concern due to allergic manifestations. We conducted an observational study on the use of an innovative Anisakis allergy diagnostic algorithm in a convenience sample of 53 allergic outpatients recruited in Western Sicily, between April 2021 and March 2022. We included individuals with an anamnesis suggestive of IgE sensitization to Anisakis reporting clinical manifestation in the last month due to allergic reactions after eating fresh fish, or in subjects at high exposure risk with sea products while abstaining from fish ingestion, excluding those with documented fish sensitization. Outpatients were tested via Skin Prick Test, IgE-specific dosage and Basophil Activation Test (BAT). Twenty-six outpatients were diagnosed with Anisakis, while 27 with Chronic Urticaria (CU). We found a seven-fold excess risk for Anisakis (p4) positivity in the Anisakis allergic outpatients, as compared to the CU ones. BAT showed the best diagnostic accuracy (92.45%) and specificity (100%), while specific IgE to Ascaris (p1) documented the best sensitivity (92.31%) but a very low specificity (37.04%). In conclusion, our findings may represent a potentially useful contribution to the future development of updated clinical guidelines.

Rapid visual detection of anisakid nematodes using recombinase polymerase amplification and SYBR Green I

Anisakidosis is a food-borne parasitic disease (FBPD) caused by the third-stage larvae of the family Anisakidae. Therefore, it is important to develop a simple, rapid and equipment-free detection method for anisakids in fish samples or seafood since current methods are time-consuming and require complex instruments. In this study, a recombinase polymerase amplification (RPA)-based method was established for the first time to detect anisakids by targeting the internal transcribed spacer (ITS) regions. The detection results were visualized by including SYBR Green I (SG) in the method. The sensitivity of RPA-SG assay was 102 copies per reaction of recombinant plasmid (within 20 min at 37°C), similar to quantitative real-time PCR (qPCR). The assay had high specificity for detecting anisakids against other related parasites and host fish. In addition, the assay was further used to detect fresh marine fish contaminated with anisakids and it showed high precision. These results indicate that the novel RPA-SG assay suitable for visual detection of anisakids in the field and food safety control.