Anisakis Larvae Research Articles

Just Hitching a Ride: Stable Isotopes Reveal Non‐Feeding Behaviour of Anisakis simplex Within Its Host Fish

ABSTRACTAnisakis simplex larvae, commonly found in marine fish, cause anisakiasis in humans, resulting in gastric to gastro‐allergic symptoms. Despite known health risks, the impact of Anisakidae larvae on fish hosts is less understood. This study aimed to investigate this interaction by assessing the feeding strategy of A. simplex. Anisakis larvae were isolated from North Sea Merluccius merluccius tissues (stomach, body cavity, liver and muscle) and were analysed for carbon (δ13C) and nitrogen (δ15N) isotope values. Significant differences in δ13C values were found among host tissues, with the liver differing from muscle and stomach tissues. In contrast, no differences were noted for the associated parasites. Additionally, δ15N values indicated that the host occupied a significantly higher relative trophic position than its parasite. This suggests a lack of direct nutrient transfer from host to parasite, as the parasite would typically exhibit higher stable isotope values than the tissue they feed on. Therefore, A. simplex's stable isotope values might reflect those of its previous host (crustacean and/or small fish), providing insights into diet and movement of the paratenic M. merluccius host. Further research is needed to confirm these findings across different fish species and to explore A. simplex as a proxy for trophic ecology.

Essential Oils of Two Subspecies of Satureja montana L. against Gastrointestinal Parasite Anisakis simplex and Acetylcholinesterase Inhibition

The increasing presence of Anisakis spp. in fish is having significant implications for public health due to a rise in cases of anisakiasis. Given this situation, there is a critical need to develop new strategies to fight this parasite. Satureja montana L., commonly known as savory, is a plant recognized in folk medicine for its therapeutic activity, such as being antispasmodic and digestive, among other properties. The aim of this study was to assess the nematicide activity against A. simplex larvae of the essential oil from two varieties of S. montana (subsp. montana (SMM) and variegata (SMV)). The essential oils were obtained via hydro-distillation of the flowering aerial parts. In vitro assays demonstrated the complete inactivation of anisakis larvae after 24 h when exposed to both essential oils, along with a significant reduction in their penetration capacity. Moreover, both essential oils showed an inhibitory effect on acetylcholinesterase (AChE). No differences between the subspecies were observed in any of the assays. Hence, the nematicidal activity of essential oils could be attributed to their capacity to inhibit AChE. These findings suggest the potential of S. montana essential oil for therapeutic and food industry applications.

Screening of Anisakis-Related Allergies and Associated Factors in a Mediterranean Community Characterized by High Seafood Consumption.

Dietary changes expose consumers to risks from Anisakis larvae in seafood, leading to parasitic diseases and allergies. Anisakis is recognized by EFSA as a significant hazard, with potential oncogenic implications. Diagnostic advancements, like the Basophil Activation Test (BAT), enhance sensitivity and accuracy in identifying Anisakis sensitization, complementing traditional IgE tests. We conducted a cross-sectional study on patients with allergic symptoms from April 2021 to April 2023 at two outpatient clinics in western Sicily. Our goal was to assess the prevalence of Anisakis-related allergies and to identify risk profiles using specific Anisakis IgE and the BAT, especially in regions with high raw fish consumption. The study evaluated specific Anisakis IgE as a screening tool for Anisakis sensitization, using questionnaires, blood samples, and immuno-allergology analyses. Anisakis-specific IgE values were compared with the BAT results, with statistical analyses including Fisher's exact test and logistic regression. The results showed an 18.5% seroprevalence of Anisakis IgE, while the BAT as a second-level test showed 4.63%, indicating the BAT's superior specificity and accuracy. The study highlighted the importance of the BAT in diagnosing Anisakis sensitization, especially in cases of cross-reactivity with Ascaris and tropomyosin. The findings confirm the BAT's exceptional specificity in identifying Anisakis sensitization and support using Anisakis-specific IgE for population-based risk profiling. The BAT can effectively serve as a confirmatory test.

The Differences of Anisakis Larvae Infection on Scads (Decapterus spp.) in the Indian Ocean off the Southern Coast of East Java Indonesia

The Differences of Anisakis Larvae Infection on Scads (Decapterus spp.) in the Indian Ocean off the Southern Coast of East Java Indonesia

KAJIAN PUSTAKA: IDENTIFIKASI DAN DISTRIBUSI SECARA GEOGRAFISENAM SPESIES ANISAKIS (NEMATODA: ANISAKIDAE) DI INDONESIA

Anisakis is a zoonotic nematode that causes anisakiasis in Europe and Asia.Food safety has recently become a major concern for consumers; therefore, accurate identification of Anisakis larvae is necessary for the correct diagnosis of Anisakis infection in humans and fish and for improving food safety. From 2001 to 2023, Anisakis examinations were carried out in 33 areas of Indonesian territory. Morphometric Anisakis of Indonesia generally have a body length of 0.10-34.50 mm with a diameter of 0.30-0.42 mm. Based on morphological and genetic identification, identified six species anisakis in Indonesia (A. simplex, A. physeteris, A. pegreffii, A. berlandi, A. typica and Anisakis sp. HC-2005), or identified six Anisakis genotypes based on genetic identification, namely A. typica (s.s), A. typica var Indonesiansis, A. physeteris, A. pegreffii, A. berlandi andAnisakis sp. HC-2005. Decapterus sp., Thyrsitoidesmarleyi, Euthynnusafifinis, Auxis rochei, Gempylus serpens, Katsuwonus pelamis and Trichiurus lepturus have a high prevalence (>90%), indicating that they are often infected with Anisakis. Anisakis spread throughout the waters in Indonesia with various types of fish as hosts and A. typica is the predominant species in Indonesia.

Behavioral and physiological changes of Anisakis simplex complex third stage larvae upon heating

There is increasing information on the time-temperature conditions that can be lethal for Anisakis larvae, but little is known about the infective potential of larvae that survive heat treatments. To characterize the risks associated with accidentally undercooked fish, in this paper, more than 5000 Anisakis larvae in the third stage (L3) were individually treated, at quasi-isothermal conditions, in a thermal cycler at 50 °C for different exposure times (0–320 s). After heat exposition, surviving larvae were collected and their locomotor activity, resistance to simulated gastric juice (SGJ), agar penetrative ability, and respiration capacity were evaluated. Results show that, even after relatively short treatments that rendered survival ratios (St50°C) close to 1 (i.e. all alive), some behavioral and physiological characteristics can be considerably impacted. Thus, L3 locomotor activity and agar penetrative ability significantly decreased after 60 s at 50 °C (S60s = 1), while heat expositions for 90 s (S90s ≈ 0.98) also reduced the resistance to SGJ and the respiration capacity. Our study reveals that the behavior of heat-treated Anisakis larvae depends on the intensity of the treatment and the longer the exposure time at 50 °C, the greater the changes observed in all the tested indicators. Further research is needed to elucidate the implications of the decline of these indicators on infectivity.

HOST SPECIFICITY, INFECTION DYNAMICS, AND ALLERGENICITY IN Anisakis SPP. INFESTATION: A REVIEW

Fish and seafood are important in providing protein to human diets. However, they are susceptible to contamination by various parasites, such as nematodes, cestodes, and trematodes. Among these, Anisakis spp. and other species of trematodes belonging to the Anisakidae family are commonly identified in fish and shellfish, posing a significant health risk. This contamination poses a substantial risk to public health, particularly with the increasing prevalence of these parasites in marine fish. The globalisation of cuisines, including sushi, is one of the factors causing this development. The risk of Anisakis contamination has increased due to the global popularity of sushi, a form of Japanese food that features raw or undercooked fish. Gastric anisakiasis is the primary infection in humans, caused by the penetration of L3 larvae into the gastric wall. However, the indefinite symptoms associated with anisakiasis make precise identification challenging, complicating efforts to effectively treat this health issue. This study reviewed the host specificity, risk factors, infection mechanisms, and infestation areas of Anisakis spp. Various reputable sources, including Google Scholar, PubMed Central, ScienceDirect, Springer Link, and the Wiley Online Library, were used to explore the diverse host preferences and the impact of environmental changes. The larvae of Anisakis spp. exhibit diverse host preferences and environmental changes like global warming make hosts more vulnerable. Inadvertent exposure to these parasites occurs when individuals consume raw or undercooked fish and seafood. An extremely serious threat is posed by allergic anisakiasis, characterised by severe symptoms such as respiratory arrest, shock, and collapse. Research focusing on bioactive substances capable of blocking or neutralising the excretions and secretions of Anisakis sp. should be encouraged. Metalloproteinases (MMPs) and serine proteases, in particular, show promise for minimising adverse effects and reducing dependency on medication in treating allergic anisakiasis. Further research and intervention techniques are essential if health issues associated with Anisakis exist.

The anti-parasitic activity of Thymus vulgaris (Thyme): A literature review

Thyme (Thymus vulgaris) is an enduring herb belonging to the mint family, Lamiaceae. It originates from the Mediterranean region and is characterized by its small, aromatic leaves, and sturdy stem. Appreciated for its robust and delightful scent, thyme is widely embraced as a culinary herb. However, its significance extends far beyond the kitchen, as it has been utilized medicinally for centuries. This is owing to the occurrence of active compounds like thymol and carvacrol, which possess noteworthy antibacterial, antioxidant, and anti-inflammatory attributes. Throughout history, thyme has been employed in the treatment of respiratory disorders, digestive ailments, and other diseases. The main objective of this study was to conduct an extensive review of the thyme plant, encompassing its classification, historical background, geographical distribution, chemical composition, and both economic and medicinal applications, particularly emphasizing its antiparasitic properties. In conclusion, apart from its well-known culinary and medicinal uses, scientific research has indicated that thyme exhibits promising effectiveness against diverse parasites. Notably, research has shown that thyme exhibited antiprotozoal activity against protozoan parasites such as Giardia lamblia, Trichomonas vaginalis, Toxoplasma gondii, Entamoeba histolytica, and others. Specific thyme extract components have shown great activity against these parasites. Thyme also has larvicidal properties, meaning that it can kill larvae. This includes Anisakis larvae, which can cause anisakiasis in humans. Thyme essential oil has been shown to effectively eliminate these larvae, suggesting that it could be used to prevent anisakiasis. Furthermore, it has also been studied for its potential to treat hepatic coccidiosis in rabbits. Research has shown that thyme oil, along with Moringa oleifera oil, can effectively reduce the number of oocysts shed by infected rabbits and improve the clinical signs of the infection. This suggests that thyme oil may be a promising therapeutic agent for tackling hepatic coccidiosis.

Prevalence and Intensity of Larvae of the Genus Anisakis sensu lato (Nematoda, Anisakidae) in Bigeye Scad, Selar crumenophthalmus (Bloch 1793), from the Indian Ocean off Java, Indonesia

This research investigates the prevalence and mean intensity of Anisakis larvae on the bigeye scad, Selar crumenophthalmus (Bloch, 1793), along the Indian Ocean off Java. In total, 498 fish samples were collected from four locations: the Indian Ocean off East Java, Yogyakarta Special Territory, Central Java, and West Java. Each fish sample was measured for length and weight, then examined for Anisakis larvae in the abdominal cavity, liver, gonads, digestive tract, and muscle. Morphological characterisation was done using scanning electron microscope (SEM). The ITS rDNA region was amplified using PCR, then used to perform RFLP for identification and sequenced to form a phylogenetic tree. The results demonstrated that the bigeye scad was vulnerable to infection by Anisakis nematodes with varying prevalence and mean intensity at each location. The bigeye scad from the Indian Ocean off East Java had the highest prevalence and mean intensity (P = 75.44 %; MI = 10.38 larvae per-host), while from West Java had the lowest prevalence (P = 1.45 %; MI = 3.33 larvae per-host). The prevalence of Anisakis in the bigeye scad tends to decrease as one moves to the west from the sampling locations. Most larvae were found in the abdominal cavity (70 %–100 %), whereas a relatively low prevalence was found in other organs. The direct sequencing in the ITS rDNA region showed that Anisakis larvae found in the bigeye scad were A. typica (Diesing, 1860), which was indicated as A. typica var. indonesiensis (A. typica sp. B). Anisakis infection can be utilised as a biological indicator for movement patterns and fish stock differentiation.

A novel rhabdovirus detected in Anisakis larvae distributed in the coastal areas of Japan: Viral genome analysis and possible coevolutionary relationship between virus and host nematodes

In the last decade, it has become evident that various RNA viruses infect helminths including Order Ascaridida. However, there is still no information available for viruses infecting Anisakis. We herewith demonstrate the presence of a novel rhabdovirus from Anisakis larvae detected by next-generation sequencing analysis and following RT-PCR. We determined the nearly all nucleotide sequence (12,376 nucleotides) of the viral genome composed of seven open reading frames, and we designated the virus as Suzukana rhabdo-like virus (SkRV). BLASTx search indicated that SkRV is a novel virus belonging to the subfamily Betanemrhavirus, rhabdovirus infecting parasitic nematodes of the Order Ascaridida. SkRV sequence was detectable only in the total RNA but not in the genomic DNA of Anisakis, ruling out the possibility of SkRV being an endogenous viral element incorporated into the host genomic DNA. When we individually tested Anisakis larvae obtained from Scomber japonicus migrating in the coastal waters of Japan, not all but around 40% were SkRV-positive. In the phylogenetic trees of Betanemrhavirus and of the host Ascaridida nematodes, we observed that evolutional distances of viruses were, to some extent, parallel with that of host nematodes, suggesting that viral evolution could have been correlated with evolution of the host. Although biological significance of SkRV on Anisakis larvae is still remained unknown, it is interesting if SkRV were somehow related to the pathogenesis of anisakiasis, because it is important matter of public health in Japan and European countries consuming raw marine fishes.

Does Anisakis spp. infestation affect the proximate composition, fatty acids, and minerals contents of its host Merluccius merlucccius?

Fish play an important role in human nutrition. They are not only a great source of protein and healthy fats, but also a unique source of essential nutrients such as omega-3 fatty acids. Moreover, most fish are parasitized, and some of these parasites are able to influence the reallocation of resources in their favor and thus reduce the nutritional quality of the fish. The present study was conducted to investigate the impact of the third stage larvae (L3) of Anisakis spp. on the proximate composition, macro-minerals (potassium, calcium, and sodium), and fatty acids of European hake (Merluccius merluccius Linnaeus, 1758). In parasitized female group, our results revealed a decrease (p< 0.005) in the amount of carbohydrate by 6.5%, of calcium by 17%, and of 2 polyunsaturated fatty acids (arachidonic acid (C20: 4w-6), and eicosapentaenoic acid (C20: 5w-3) with 33% and 15% respectively. Simultaneously, an increase by 25% in the level of a single saturated fatty acid C10:0 was noticed. According to the principal component analysis, the parasitized female was wealthy of saturated fatty acids and monounsaturated fatty acids and contains less of polyunsaturated fatty acids, omega-3 fatty acids, and omega-6 fatty acids than the unparasitized female and male. No significant changes were observed in the biochemical composition of male hake, probably due to the low mean intensity of L3 larvae of Anisakis spp. in this group.

An Epidemiological Update on Anisakis Nematode Larvae in Red Mullet (Mullus barbatus) from the Ligurian Sea.

Red mullet (Mullus barbatus) is a commercially relevant fish species, yet epidemiological data on anisakid nematode infestation in M. barbatus are scarce. To fill this gap, we report the occurrence of Anisakis larvae in red mullet in the Ligurian Sea (western Mediterranean). This survey was performed between 2018 and 2020 on fresh specimens of M. barbatus (n = 838) from two commercial fishing areas (Imperia, n = 190; Savona, n = 648) in the Ligurian Sea. Larvae morphologically identified as Anisakis spp. (n = 544) were characterized using PCR-RFLP as Anisakis pegreffii. The overall prevalence of A. pegreffii was 24.46%; the prevalence at each sampling site was 6.32% for Imperia and 29.78% for Savona. Furthermore, 3300 larvae of Hysterothylacium spp. were detected in the visceral organs of fish coinfected with A. pegreffii, showing that coinfection with two parasitic species is not rare. This study provides a timely update on the prevalence of ascaridoid nematodes in red mullet of the Ligurian Sea, an important commercial fishing area in the Mediterranean.

Occurrence of Anisakis larvae in Atlantic horse mackerel (Trachurus trachurus) sold in the city of Marrakesh, Morocco

Human anisakidosis is a parasitic infection caused by the ingestion of nematode larvae of the Anisakidae family contained in various organs of fish and cephalopods consumed raw or undercooked. The aim of this work was to detect and identify morphologically and genetically (PCR and sequencing) the nematode larvae present in both flesh and abdominal cavity of horse mackerel (Trachurus trachurus) which are widely consumed by the population of Marrakesh. For this purpose, 299 fish were purchased at the wholesale market in refrigerated conditions. They were originated from seven different landing ports along the Atlantic coast (Agadir, Dakhla, El Jadida, Essaouira, Mohammedia, Safi and Sidi Ifni). The fishes were analyzed from November 2017 to December 2019, and 4815 larvae were detected out of 294 positive horse mackerel. This resulted in a prevalence of 98.33% and a mean intensity of 16.38 larvae per fish. Horse mackerel from Mohammedia, El Jadida, Safi, Essaouira, Agadir and Sidi Ifni were more infested than those from Dakhla with a mean intensity of 25.29, 21.33, 18.88, 16.15, 15.90 and 13.86 larvae per fish, respectively, while that from Dakhla was the least infested with a mean intensity of 11.83. These results could be explained by the availability of primary intermediate hosts of Anisakis spp., such as crustaceans (shrimps), which are more abundant in the northern Moroccan Atlantic coast. Furthermore, we have recorded a higher infection in fish during warm seasons (spring and summer) than during cold ones. We also have noticed that as the distance from the fishing area increased, the larvae had more time to migrate from the abdominal cavity to the muscles. All detected larvae were identified morphologically as Anisakis type I and genetically as Anisakis simplex sensu stricto. Statistical analysis showed that the intensity of infection by Anisakis L3 larvae was positively correlated with the weight of horse mackerel and that origin had no impact on fish parasitism.

Oral intake of a widely available gastrointestinal OTC medicine ‘Seirogan’ is effective for gastric anisakiasis (Anisakis food poisoning)

Gastric food poisoning due to anisakid nematodes (gastric anisakiasis) is characterized by severe stomach pain caused by the consumption of raw fish that harbors anisakid nematodes. The only effective treatment that is currently available is the endoscopic removal of nematodes penetrating the stomach wall. An in vitro study showed that the widely available over-the-counter (OTC) gastrointestinal medicine 'Seirogan' containing wood creosote kills Anisakis larvae. In addition, two cases in which the oral intake of Seirogan alleviated gastric anisakiasis symptoms have been reported. Herein, we analyzed 56 statements regarding Seirogan's efficacy against gastric anisakiasis posted on social networking sites (SNSs) in Japan. There were 33 statements (59%) that Seirogan was effective in significantly alleviating or eliminating symptoms of gastric anisakiasis, 13 comments (23%) stating that it had a slight effect, and 10 comments (18%) stating that there was no effect. These results indicate that in many cases, an oral intake of Seirogan is effective as first aid to remove or alleviate severe stomach pain due to gastric anisakiasis.

Prevalence of Anisakis larvae in cultured mackerel Scomber japonicas in Japan and the relationship between the intensity of Anisakis infection in cultured mackerel and fish fatness

Incidences of food poisoning caused by Anisakis have increased in Japan, and a significant number of anisakiasis cases in Tokyo attributed to the consumption of mackerel (Scomber japonicus) have been reported. There are two types of cultured mackerel in Japan: those cultured fully from controlled parent fish eggs and those cultured from wild juveniles collected from the sea. In this study, we aimed to investigate the prevalence of Anisakis larvae in cultured mackerel (184 fish) in 15 products and identified the species using molecular analysis to evaluate the risk of food poisoning. In total, 1567 Anisakis larvae were detected in 70 of 130 mackerel in 10 products; however, Anisakis larvae were not detected in 54 mackerel using artificially reared juveniles in 5 products. Moreover, 277 larvae were detected in fish muscle, and 98.6 % (273/277 larvae) were molecularly identified as Anisakis simplex sensu stricto (A. simplex). Conversely, 1043 Anisakis pegreffii larvae were identified genetically and/or morphologically but only 2 larvae were identified in the muscle. There was no significant relationship between the host coefficient of fatness and the infection intensity of Anisakis larvae in individual fish (Spearman's rank correlation coefficient test, P > 0.05). Based on the results of the analysis of the cytochrome c oxidase subunit2 (cox2) gene of A. simplex and A. pegreffii detected in this study, we attempted to estimate the catch area of the juveniles (Pacific stock and Tsushima Warm Current stock). The clusters on the phylogenetic tree of the cox2 gene of A. pegreffii from the mackerel presumed to be the two above mentioned geographic distributions were not separated and these geographic origins could not be estimated. This study revealed that mackerel cultured using wild juveniles are likely to be contaminated with Anisakis larvae, which can be detected not only in the visceral organs, but also in the muscle. Anisakis infection in cultured mackerel did not influence fish growth and evaluating the intensity of Anisakis based on the fatness level of the mackerel was complicated. To prevent anisakiasis caused by the consumption of mackerel cultured using wild juveniles, it is important to steadily control Anisakis through heating and freezing.

Modeling survival curves of Anisakis L3 after isothermal heat treatments at lethal temperatures

Even though anisakiasis is considered, nowadays, a significant threat to public health all over the world, no attempt has been made up to date to mathematically describe the thermal susceptibility of Anisakis larvae in the third stage (L3). To fill this gap, in this paper, more than 10,000 free (non-encysted) Anisakis L3 were individually heat treated in a thermal cycler at temperatures between 44 °C and 61 °C for different exposure times. After heat exposition, viability was assessed in each larva, survival curves at isothermal conditions were derived, and the effectiveness of four kinetic models (fundamental kinetic model, Mafart model, and probit and logit models) in describing these curves was tested. Evaluation of larvae viability after heat exposition revealed sigmoidal survival curves that increased their steepness with temperature. Of the four models tested, the Mafart model was the one that best fitted the data only differing from the observed survival ratios by 0.12 units on average. Validation experiments performed at temperatures different to those used to create the model corroborated its predictive capacity. Future efforts should be focused in predicting larvae viability at non-isothermal conditions as those occurring during fish cooking.

A case of chronic gastric anisakiasis coexisting with early gastric cancer.

Anisakiasis is a parasitic disease caused by the consumption of raw or undercooked fish that is infected with Anisakis third-stage larvae. In countries, such as Japan, Italy, and Spain, where people have a custom of eating raw or marinated fish, anisakiasis is a common infection. Although anisakiasis has been reported in the gastrointestinal tract in several countries, reports of anisakiasis accompanied by cancer are rare. We present the rare case of a 40-year-old male patient with anisakiasis coexisting with mucosal gastric cancer. Submucosal gastric cancer was suspected on gastric endoscopy and endoscopic ultrasonography. After laparoscopic distal gastrectomy, granulomatous inflammation with Anisakis larvae in the submucosa was pathologically revealed beneath mucosal tubular adenocarcinoma. Histological and immunohistochemical investigation showed cancer cells as intestinal absorptive-type cells that did not produce mucin. Anisakis larvae could have invaded the cancer cells selectively because of the lack of mucin in the cancerous epithelium. Anisakiasis coexisting with cancer is considered reasonable rather than coincidental. In cancer with anisakiasis, preoperative diagnosis may be difficult because anisakiasis leads to morphological changes in the cancer.

Türk Süpermarketlerindeki İthal Balıklarda Zoonotik Anisakis Larvalarının Varlığına İlişkin Devam Eden Veriler: Dondurulmuş Atlantik Uskumru (Scomber Scombrus) ve Füme Atlantik Somonu (Salmo Salar)

Anisakis pegreffii and A. simplex sensu stricto (s.s.) are the main etiological agents causing human anisakiasis. Here, we aimed to investigate based on the pepsin digestion method of the occurrence of Anisakis larvae in imported deep-frozen whole Atlantic mackerel (Scomber scombrus) from FAO 27 to Turkey and smoked Norwegian farmed Atlantic salmon fillets (Salmo salar) between 2018 and 2019. A total of 100 whole Atlantic mackerel and 180 Atlantic salmon fillets were randomly sampled from local Turkish supermarkets. No Anisakis larvae were detected in smoked Atlantic salmon fillets. In total, 827 Anisakis larvae were found in mackerel, and the prevalence was 68% (68/100). The mI and mA of Anisakis larvae in mackerel were 13.1 and 8.2, respectively. Whereas the 95.28% (788/827) of the Anisakis larvae were found in abdominal cavity/viscera, the 4.72 % (39/827) of the larvae in the muscle. The prevalence and mI of Anisakis larvae in the abdominal cavity/viscera and muscle of mackerel was 63.0% (63/100) and 42.0% (42/100), and 12.5 and 0.9, respectively. The subsample of 100 larvae was molecularly identified by ITS RFLP patterns. The 99 (99.0%) larvae were identified as A. simplex (s.s.), and 1 (1.0%) larva was A. pegreffii. Consequently, there is low or no risk of anisakiasis in smoked farmed Atlantic salmon for Turkish consumers. The 42.0% prevalence of zoonotic Anisakis species larvae in imported Atlantic mackerel fillets could have public health risk in Turkish consumers for anisakiasis or allergy.

Prevalence and abundance of Anisakis larvae in ready-to-eat mackerel products in Japan

The risk of contracting anisakiasis from consuming ready-to-eat (RTE) mackerel products in Japan was investigated by examining the prevalence and abundance of Anisakis simplex and its sibling species in these products. From 2019 to 2021, a total of 448 RTE mackerel products were purchased in Japan. Anisakis larvae were isolated from 244 of the 448 samples (54 %), and live larvae were isolated from 161 of the 448 samples (36 %). In total, 3170 Anisakis larvae, which included 919 live larvae, were isolated. The isolated Anisakis larvae consisted of 3118 A. simplex (s. s.), 27 A. pegreffii, and 25 hybrid genotype (A. simplex [s. s.] × A. pegreffii) larvae. No A. berlandi larvae were isolated. The prevalence of larvae in samples of mackerel caught in the Southern Japan region and Sea of Japan was much lower than that in mackerel caught in other areas. Both the prevalence of Anisakis larvae in all samples and their abundance in larvae-positive samples exhibited specific seasonal variations, being high in spring.

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

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.