Location and elimination of Anisakis simplex third stage larvae in Atlantic herring Clupea harengus L

We here describe the location of anisakid third stage larvae in Atlantic herring Clupea harengus L. caught in the North Sea in August 2023. We further demonstrate how industrial processing (mechanical gutting, removal of entrails, head, tail, hypaxial anterior musculature and vertebral column) reduces the overall infection and worm load in the musculature. The isolated anisakid larvae were identified as Anisakis simplex sensu stricto by a combination of morphometrics and molecular methods (PCR of rDNA and mtDNA, sequencing, BLAST analysis). As a baseline we examined a total of 75 specimens of freshly caught and ungutted herring and showed a positive correlation between host size (fish length and weight) and infection level. The overall prevalence of infection was 84 %, the mean intensity 11.3 (range 1-38 parasites per fish) and the abundance 9.52. The main part of the overall worm population was associated with stomach and pyloric caeca in the body cavity (77 %) and only 5 % was found in the musculature. Larvae occurred in the hypaxial part of the musculature (21), the epaxial part (7 worms) and the caudal part (5 worms). The prevalence of muscle infection was 28 % and the mean intensity 1.6 (range 1-5) parasites per fish and abundance 0.44 parasites per fish. In order to assess the effect of industrial processing on worm occurrence in the fish we examined a total of 67 specimens of herring, from exactly the same batch, but following processing. This included removal of organs in the body cavity, cutting the lower part of the hypaxial segment but leaving the right and left musculature connected by dorsal connective tissue. Five out of these fish carried one larva (prevalence 7.5%, mean intensity 1, abundance 0.07 larvae per fish), and these worms were located in the ventral part of the anterior musculature (2), in the central part of the anterior musculature (2) and one larva in the central part of the caudal musculature. The industrial processing reduced the overall occurrence (abundance) of worms in the fish from 9.52 to 0.07 (136 times reduction) and the occurrence in the musculature from 0.44 to 0.07 (6.28 times reduction). The overall prevalence was reduced from 84 % to 7.5 % (11.2 times reduction). Muscle infection prevalence fell from 28 % to 7.5 % (3.7 times reduction). We then followed another batch of herring following a marinating process (11% NaCl for 24 h and subsequent incubation in acetic acid and vinegar) by artificially digesting the flaps during week 1-8. Although a total of 31 larvae were recovered from 144 fish examined no live nematode larvae were isolated. The importance of fish handling, processing and marination for consumer safety is discussed.

Re-evaluation of certain aspects of the EFSA Scientific Opinion of April 2010 on risk assessment of parasites in fishery products, based on new scientific data. Part 1: ToRs1-3

Surveillance data published since 2010, although limited, showed that there is no evidence of zoonotic parasite infection in market quality Atlantic salmon, marine rainbow trout, gilthead seabream, turbot, meagre, Atlantic halibut, common carp and European catfish. No studies were found for greater amberjack, brown trout, African catfish, European eel and pikeperch. Anisakis pegreffii, A. simplex (s. s.) and Cryptocotyle lingua were found in European seabass, Atlantic bluefin tuna and/or cod, and Pseudamphistomum truncatum and Paracoenogonimus ovatus in tench, produced in open offshore cages or flow-through ponds or tanks. It is almost certain that fish produced in closed recirculating aquaculture systems (RAS) or flow-through facilities with filtered water intake and exclusively fed heat-treated feed are free of zoonotic parasites. Since the last EFSA opinion, the UV-press and artificial digestion methods have been developed into ISO standards to detect parasites in fish, while new UV-scanning, optical, molecular and OMICs technologies and methodologies have been developed for the detection, visualisation, isolation and/or identification of zoonotic parasites in fish. Freezing and heating continue to be the most efficient methods to kill parasites in fishery products. High-pressure processing may be suitable for some specific products. Pulsed electric field is a promising technology although further development is needed. Ultrasound treatments were not effective. Traditional dry salting of anchovies successfully inactivated Anisakis. Studies on other traditional processes - air-drying and double salting (brine salting plus dry salting) - suggest that anisakids are successfully inactivated, but more data covering these and other parasites in more fish species and products is required to determine if these processes are always effective. Marinade combinations with anchovies have not effectively inactivated anisakids. Natural products, essential oils and plant extracts, may kill parasites but safety and organoleptic data are lacking. Advanced processing techniques for intelligent gutting and trimming are being developed to remove parasites from fish.

EAACI Molecular Allergology User's Guide 2.0

Since the discovery of immunoglobulin E (IgE) as a mediator of allergic diseases in 1967, our knowledge about the immunological mechanisms of IgE-mediated allergies has remarkably increased. In addition to understanding the immune response and clinical symptoms, allergy diagnosis and management depend strongly on the precise identification of the elicitors of the IgE-mediated allergic reaction. In the past four decades, innovations in bioscience and technology have facilitated the identification and production of well-defined, highly pure molecules for component-resolved diagnosis (CRD), allowing a personalized diagnosis and management of the allergic disease for individual patients. The first edition of the "EAACI Molecular Allergology User's Guide" (MAUG) in 2016 rapidly became a key reference for clinicians, scientists, and interested readers with a background in allergology, immunology, biology, and medicine. Nevertheless, the field of molecular allergology is moving fast, and after 6 years, a new EAACI Taskforce was established to provide an updated document. The Molecular Allergology User's Guide 2.0 summarizes state-of-the-art information on allergen molecules, their clinical relevance, and their application in diagnostic algorithms for clinical practice. It is designed for both, clinicians and scientists, guiding health care professionals through the overwhelming list of different allergen molecules available for testing. Further, it provides diagnostic algorithms on the clinical relevance of allergenic molecules and gives an overview of their biology, the basic mechanisms of test formats, and the application of tests to measure allergen exposure.

The artificial digestion method underestimates the viability of Anisakis simplex (s.l.) L3 present in processed fish products

This work studied the performance of the artificial digestion method in terms of recovery and viability of Anisakis simplex third-stage larvae (L3) when previous treatments given to the infected fish muscle may accidentally render viable larvae. For that: a) hake mince was spiked with 10 L3/75g mince, frozen at -10, -15, -20, and -30 °C and immediately thawed, or stored for 12 or 24 h, and subjected to pepsin digestion; b) the mince was spiked under the same conditions, frozen at the above temperatures and thawed immediately. After manual recovery, L3 were assessed for viability, used to spike again the minced fish and subjected to pepsin digestion; c) the mince was spiked with 10 L3 which were: i) living (i.e. chilled), ii) freeze-surviving (live L3 had been previously recovered after freezing at -10 °C), or iii) dead (frozen at -30 °C or - 80 °C), and then subjected to pepsin digestion. Results showed that the artificial digestion method kills a significant number of larvae that may have survived freezing and thus may underestimate the number of viable larvae in a given batch. The method may also underestimate the infection level of fish batches containing dead larvae. It is suggested to take these limitations into account when designing digestion protocols for specific applications, especially when there is a risk of insufficiently treated or cooked fish batches or ready-to-eat foods.

How effective is freezing at killing Anisakis simplex, Pseudoterranova krabbei, and P. decipiens larvae? An experimental evaluation of time-temperature conditions

The consumption of raw or inadequately cooked marine fish can lead to several disorders caused by the ingestion of viable anisakid nematodes. Although anisakid larvae can be killed by subzero temperatures, making freezing an important control measure for this potential health hazard, these parasites can survive freezing under some conditions. Therefore, the aim of the present study was to experimentally evaluate the time-temperature conditions needed to kill Anisakis simplex and Pseudoterranova spp. The effectiveness of freezing was tested on two species of fish: cod, Gadus morhua from the North Atlantic, and herring, Clupea harengus membras from the southern Baltic Sea. Samples, which comprised skinless fillets of cod (n = 40) with visible parasites and whole herring (n = 240), were separately frozen at − 15, − 18, or − 20 °C for 24 h, or at − 20 °C for 48 h in the single-compressor freezer and at − 20, − 25, or − 35 °C for 24 h in the double-compressor freezer. After thawing, parasites were stained with malachite green and examined under the microscope for viability. All A. simplex and Pseudoterranova spp. larvae in cod fillets died at a temperature of − 15 °C or lower. However, freezing did not kill all the A. simplex larvae in whole herring: spontaneous movement of these parasites was observed in samples stored in the single-compressor freezer at − 15, − 18, and − 20 °C over 24 h. Our results demonstrate that the freezing procedure must consider both the capability of the freezing device and the nature of the fish product to ensure consumer safety.

Respiratory analysis as a tool to detect physiological changes in Anisakis larvae subjected to stress

Human infection due to eating fish parasitized by live Anisakis larvae in the third stage is considered an important health problem, and the application of treatments to ensure their mortality in the fish products is crucial to prevent the risk of infection. Mobility is used to assess viability, but mobile larvae may not always be infective and immobile larvae may be erroneously considered as non-viable. The objective was to establish whether the analysis of respiratory activity by means of the oxygen consumption rate (OCR) of Anisakis could be used to identify subtle differences between larvae that were still considered viable in terms of their mobility but had been subjected to thermal and/or chemical stress. The metabolic modulators FCCP [carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone] and sodium azide were used and the basal, maximum, spare and residual respiration rates calculated. Results showed that maximum respiratory capacity of larvae subjected to freezing significantly decreased immediately after thawing, but after some acclimatization, they recovered their capacity fully. However, when these larvae were stored at 4.6 °C, their mitochondria became dysfunctional faster than those of untreated larvae. OCR also showed that mitochondria of larvae were affected by incubation at 37 °C in NaCl or gastric juice. To conclude, OCR of Anisakis in the presence of metabolic modulators can help to identify subtle changes that occur in the larva. These measurements could be used to characterize larvae subjected to various stresses so that a broader picture of Anisakis pathogenic potential can be gained.