Anisakis can cause Anisakiasis in humans if raw or undercooked fish is consumed. Symptoms of infection may include vomiting, acute abdominal symptoms, or allergies. In this study, we collected 187 commercially available marine fish from the Yellow Sea, East China Sea, and South China Sea. Among them, 79 were found positive containing 520 Anisakis worms. The average prevalence rate was found 42% in this investigation. Ninety-two worms from different sea areas were selected and analyzed for identification, revealing the presence of five different species, which are Anisakis pegreffii, Hysterothylacium aduncum, Hysterothylacium zhoushanense, Hysterothylacium amoyense, and Hysterothylacium sp. In the meta-analysis, three databases: PubMed, CNKI, and BaiduXueshu were searched for surveys on the prevalence of Anisakis in Chinese waters from January 2000 to December 2023. A total of 26 studies were included in this analysis of which 25 publications were retrieved from different databases and one being the present study. The pooled prevalence of Anisakis was 45% among commercially available marine fish. Variances in the prevalence of Anisakis were noted among the four seas, with the highest rates in the East China Sea and the Bohai Sea, reaching 53% [0.38; 0.68] and 49% [0.36; 0.62], respectively. The Prevalence of Anisakis infection was significantly higher in astern parts such as Liaoning, Shanghai, and Zhejiang. Analysis of the host fish subgroups revealed that the orders of Anguilliformes, Scombriformes, and Gadiformes had high rates of infection. These findings suggest a significant prevalence of Anisakis, posing an increasing risk of infection for individuals. This study provides impactful information for implementing preventative measures against Anisakis.

BACKGROUND: Human fishing activities have significantly affect environmental concern for marine ecosystems, conservation of marine mammals, and human health. Coastal cetaceans are highly vulnerable to ingestion of fishing gear, bycatching, or entanglement, all of which can be fatal for these animals. In particular, certain coastal dolphins and porpoises are heavily impacted by fishing gear such as angling gear or stownet, as their food often overlap with the target fish species of human fisheries.
METHODS: This study presents a case of an Indo-Pacific finless porpoise (Neophocaena phocaenoides) beached on the coast of Jeju Island, Republic of Korea, with ingestion of fishing gear and severe Anisakis infection. Although this species inhabits waters ranging from the Persian Gulf to Taiwan, several stranded carcasses have been reported on Jeju Island in recent years. Post-mortem computed tomography revealed a bundle of four fishing hooks in the forestomach, along with nylon lines and steel lines with connectors, which were assumed to be angling gear for Jeju hairtail (Trichiurus lepturus). Further necroscopic investigation revealed that the forestomach contained a large number of Anisakis spp. (Nematoda: Anisakidae). Histological examination revealed a thickened forestomach wall with pinpoint and volcanic ulcerations, a thickened layer of stratified squamous epithelium, and infiltrated stroma in the squamous epithelium.
CONCLUSIONS: This study emphasizes the urgent need to address the impact of fishing activities on marine mammals, marine litter pollution, and the bycatch problem in Korean seawater. In addition, the occurrence of N. phocaenoides in seawater around Jeju Island should be raised in future geographical ecology or veterinary pathology studies and when its distribution is updated.

Many pathogens are related to carcinogenesis. Chronic inflammation, as a result of persistent infection, leads to DNA damage, higher expression of oncogenes, decreased apoptosis and immunosuppression, which are some of the reasons for cancer induction. Among parasites, Schistosoma, Opistorchis and Clonorchis are recognised as infectious agents which contribute to cancer. A relationship between Anisakis and cancer was hypothesised because cellular responses to Anisakis products could result in inflammation and DNA damage. Previous research has shown a decrease in CD8+ γδ T-cells and an increase in αβ and γδ T-cell apoptosis in colon cancer (CC) samples. Ninety-two CC patients and 60 healthy subjects were recruited. γδ and αβ T-cells were analysed, and their apoptosis was evaluated. Anti-Anisakis antibodies were tested in sera from CC patients and controls. Anti-Anisakis IgG, IgM, IgA and IgE antibodies were significantly higher in CC patients. A significant increase in anti-Anisakis IgA levels was observed in patients with angiolymphatic invasion. The number of all γδ T-cells, as well as CD3+ CD4+ αβ T-cells, was significantly lower in CC patients. The apoptosis of all T-cells was significantly increased in patients with CC. We observed a significantly higher percentage of anti-Anisakis IgE positive patients having a deficit of CD3+ γδ T-cells. Our results suggest a relationship between Anisakis and CC.

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.

UNASSIGNED: Anisakis infects humans by consuming contaminated undercooked or raw fish, leading to gastric anisakiasis, gastro-allergic anisakiasis, or asymptomatic contamination. Although larvae usually die when penetrating the gastric tissue, cases of intra- and extra-abdominal spread were described. We report the first probable case of pericardial anisakiasis.
UNASSIGNED: A 26-year-old man presented to the emergency department because of progressive lower limb oedema and exertional dyspnoea. Two months prior, he had consumed raw fish without any gastrointestinal symptoms. The echocardiogram reported a circumferential pericardial effusion (\'swinging heart\') and mildly reduced left ventricular ejection fraction (LVEF). He was diagnosed with myopericarditis after a cardiac magnetic resonance. A fluorodeoxyglucose positron emission tomography scan revealed an intense pericardial metabolism. Blood tests exhibited persistent eosinophilia and mild elevation of Anisakis simplex IgE-as for past infestation. A pericardial drainage was performed, subsequently, serial echocardiograms revealed a spontaneous recovery of his LVEF. No autoimmune, allergic, or onco-haematologic diseases were identified. Based on a history of feeding with potentially contaminated raw fish and on long-lasting eosinophilia, we suspected a pericardial anisakiasis, despite a low but persistent titre of specific IgE. Albendazole was administered for 21 days, along with colchicine and ibuprofen for 2 months; pericardial effusion resolution and eosinophil normalization occurred two weeks after.
UNASSIGNED: We hypothesized that Anisakis larvae may have migrated outside the gastrointestinal tract, penetrating the diaphragm and settling in the pericardium, causing pericarditis and pericardial effusion. Clinicians should know that the pericardium may be another extra-abdominal localization of anisakiasis, beyond pleuro-pulmonary involvement.

Consumption of raw and mildly processed seafood, in the context of modern Western world eating trends, is recognized as a major driver for human fish-borne infections. However, these zoonoses and their unfamiliar risks remain neglected and underappreciated among European diagnosticians. In contemporary Europe anisakidosis is one of the most important fish-borne zoonoses. It is caused by ingesting the third-stage infective larvae of the nematode parasites that belong to the family Anisakidae. The case described herein, is an intestinal and ectopic form of anisakiosis (Anisakis spp.), causing symptoms of subacute abdomen and masquerading as an intraperitoneal malignancy. It is the first anisakidosis case reported in Greece, affecting a young patient who had been repeatedly exposed to the parasite by consuming homemade raw fish. Right hemicolectomy, omentectomy and excision of a descending colon nodule were uneventfully performed. The pathology report confirmed granulomatous tissue with eosinophilic infiltration and parasites that were morphologically and molecularly identified as Anisakis spp. Although challenging, acquiring an accurate diagnosis of anisakidosis can prevent unnecessary surgery, as the infection typically is self-resolving, and if treatment is deemed necessary, it can be limited to antiparasitic medication. However, in rare cases, extra-gastrointestinal migration of larvae can cause severe damage with practically unknown risks, posing a diagnostic and therapeutic dilemma. In such a clinical case scenario, surgical exploration can decisively contribute to a definitive diagnosis and early identification of intraabdominal complications necessitating surgical intervention.

A 53-year-old patient experienced 2 Anisakis-induced allergic episodes: the first with anaphylaxis, the second presenting with gastric symptoms and progressing to systemic anaphylaxis. The case could suggest a common pathophysiology involving allergic reactions in gastric anisakiasis and Anisakis allergy.

Globally, the exploitation of small pelagic fish, like Pacific mackerel is of great importance due to food industry demand. However, there are few studies regarding its parasites load and there are no in this geographic zone. This study aimed to assess the parasitic composition, some temporal changes (during spring and summer) in abundance, prevalence and intensity of infection parasitic of the Pacific mackerel (Scomber japonicus) from Todos Santos Bay, Baja California, Mexico. The parasite fauna of the Pacific mackerel consisted of 1930 parasites (1413 in spring and 517 in summer) distributed in the follow taxa: an Tetraphyllidea (Cestoda), Kuhnia scombri (Monogenea), Didymozoidae (Digenea), Anisakis sp. (Nematoda), Rhadinorhynchus sp. (Acanthocephala) and Caligus pelamydis (Copepoda). The nematodes parasite were the most abundant both in spring with a mean abundance of 27.6 parasites and in summer 8.2 parasites compared with the other taxa like Cestoda, Monogenea, Digenea, Acanthocephala and Copepoda (P = 0.003). The mean intensity of the nematodes in spring and summer was 28.1 and 13.4, respectively. The nematodes prevalence was 90 % in spring and 60 % in summer. In general, the parasite load is more abundant in spring than summer. In summer, absence of taxa as Cestoda and Copepoda were registered. Nematode larvae were present in the fish guts mesentery and inside of the stomach, pyloric caeca, intestine. Also the nematodes were found in the liver, muscle and gonads. The most affected organ by nematodes was the intestine mesentery. The most predominant parasite of this study has been Anisakis sp. during spring.

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.

The European conger, Conger conger, is a benthic marine fish species with a geographical distribution extending through the northeastern Atlantic and the Mediterranean. Despite being extensively distributed and widely appreciated by Spanish consumers, studies regarding parasite presence in this fish are scarce. In the present work, a hundred and eight specimens from the Mediterranean coast of northeastern Spain (Catalan waters) were surveyed for the presence of nematode parasites. Several species were morphologically identified: third-stage larvae of Anisakis type I (sensu Berland, 1961) (n = 131), third-stage larvae of Anisakis type II (sensu Berland, 1961) (n = 18), third- and fourth-stage larvae and adults of Hysterothylacium spp. (n = 48), adults of Cucullanus sp. (n = 391), and adults of Cristitectus congeri (n = 69). Moreover, some fish and decapode species were also observed as part of the host\'s diet, with the most detected preys being Micromesistius poutassou, Sardina pilchardus, Macropipus sp., and Goneplax rhomboides. This represents the first survey of nematode parasites infecting C. conger from the northeastern Spanish Mediterranean waters. Among the parasite species detected, the presence of Anisakis species should be highlighted as the ingestion of C. conger parasitized with these larvae could potentially lead to anisakiasis in consumers.