A review was conducted to identify the most common causative agents of anisakidosis, the methods used for identification of the causative agents, and to summarize the sources of infection, and patients\' demographics. A total of 762 cases (409 articles, inclusive of all languages) were found between 1965 and 2022. The age range was 7 months to 85 years old. Out of the 34 countries, Japan, Spain, and South Korea stood out with the highest number of published human cases of anisakidosis, respectively. This raises the question: Why are there few to no reports of anisakidosis cases in other countries, such as Indonesia and Vietnam, where seafood consumption is notably high? Other than the gastrointestinal tract, parasites were frequently found in internal organs such as liver, spleen, pancreas, lung, hiatal and epigastric hernia, and tonsils. There are also reports of the worm being excreted through the nose, rectum, and mouth. Symptoms included sore throat, tumor, bleeding, gastric/epigastric/abdominal/substernal/lower back/testicular pain, nausea, anorexia, vomiting, diarrhea, constipation, intestinal obstruction, intussusception, blood in feces, hematochezia, anemia, and respiratory arrest. These appeared either immediately or up to 2 months after consuming raw/undercooked seafood and lasting up to 10 years. Anisakidosis commonly mimicked symptoms of cancer, pancreatitis, type I/II Kounis syndrome, intussusception, Crohn\'s disease, ovarian cysts, intestinal endometriosis, epigastralgia, gastritis, gastroesophageal reflux disease, hernia, intestinal obstruction, peritonitis, and appendicitis. In these cases, it was only after surgery that it was found these symptoms/conditions were caused by anisakids. A range of not only mainly marine but also freshwater fish/shellfish were reported as source of infection. There were several reports of infection with >1 nematode (up to >200), more than one species of anisakids in the same patient, and the presence of L4/adult nematodes. The severity of symptoms did not relate to the number of parasites. The number of anisakidosis cases is grossly underestimated globally. Using erroneous taxonomic terms, assumptions, and identifying the parasite as Anisakis (based solely on the Y-shaped lateral cord in crossed section of the parasite) are still common. The Y-shaped lateral cord is not unique to Anisakis spp. Acquiring a history of ingesting raw/undercooked fish/seafood can be a clue to the diagnosis of the condition. This review emphasizes the following key points: insufficient awareness of fish parasites among medical professionals, seafood handlers, and policy makers; limited availability of effective diagnostic methodologies; and inadequate clinical information for optimizing the management of anisakidosis in numerous regions worldwide.

Alive anisakids cause acute gastrointestinal diseases, and dead worms contained in food can provoke sensibilization and allergic reactions in humans. Detected in the purchased minced salmon Oncorhynchus nerka nematodes were identified as Anisakis simplex sensu stricto (Anisakidae). We found that recently published phylogenetic trees (reconstructed using different ribosomal and mitochondrial genetic markers) showed independent clusterization of species recognized in the A. simplex sensu lato species complex. This prompted us to undertake this full-fledged molecular genetics study of anisakids from Kamchatka with phylogenetic reconstructions (NJ/ML) and calculated ranges of interspecific and intergeneric p-distances using ITS1-5.8S-ITS2 sequences. We confirmed that molecular markers based on the ITS region of rDNA were able to recognize \'pure\' specimens belonging to the cryptic species. We offer new insights into the systematics of anisakids. The genus Anisakis sensu stricto should include Anisakis simplex sensu stricto, Anisakis pegreffii, Anisakis berlandi, Anisakis ziphidarum, and Anisakis nascettii. Presumably, two genera should be restored in the structure of the subfamily Anisakinae: Skrjabinisakis for the species Anisakis paggiae, Anisakis brevispiculata, and Anisakis physeteris; and Peritrachelius for the species Anisakis typica. In addition, we provide the short annotated list of some genera of the family Anisakidae, including their diagnoses.

Nematodes of the Anisakidae family have the ability to infest a wide variety of aquatic hosts during the development of their larval stages, mainly marine mammals, aquatic birds, such as pelicans, and freshwater fish, such crucian carp, these being the hosts where the life cycle is completed. The participation of intermediate hosts such as cephalopods, shrimp, crustaceans and marine fish, is an important part of this cycle. Due to morphological changes and updates to the genetic information of the different members of the family, the purpose of this review was to carry out a bibliographic search of the genus and species of the Anisakidae family identified by molecular tests, as well as the geographical area in which they were collected. The Anisakidae family is made up of eight different parasitic genera and 46 different species. Those of clinical importance to human health are highlighted: Anisakis pegreffi, A. simplexsensu stricto, Contracaecumosculatum, Pseudoterranova azarazi, P. cattani, P. decipiens and P. krabbei. The geographical distribution of these genera and species is located mainly in the European continent, Asia and South America, as well as in North and Central America and Australia. Based on the information collected from the Anisakidae family, it was determined that the geographical distribution is affected by different environmental factors, the host and the ability of the parasite itself to adapt. Its ability to adapt to the human organism has led to it being considered as a zoonotic agent. The disease in humans manifests nonspecifically, however the consumption of raw or semi-raw seafood is crucial information to link the presentation of the parasite with the disease. The use of morphological and molecular tests is of utmost importance for the correct diagnosis of the genus and species of the Anisakidae family.

The Japanese threadfin bream N. japonicus (Bloch) (Perciformes: Nemipteridae) is an important marine food fish in Asia. However, our present knowledge of the occurrence of its nematode parasites is still limited. In the present study, the species composition and infection rate of ascaridoid nematodes in N. japonicus from the South China Sea, were studied for the first time. Five ascaridoid species, namely Anisakis typica (L3), Hysterothylacium amoyense (L3), Hysterothylacium sp. IV-A (L3), adult of H. thalassini and Raphidascaris lophii (L3), were identified using integrative taxonomy. Hysterothylacium amoyense was the most prevalent species (prevalence 47.2%, mean intensity 14.9 ± 17.1). Hysterothylacium thalassini and R. lophii were reported in the Japanese threadfin bream for the first time. Two different genotypes of A. typica (overall prevalence of 3.4%; mean intensity 1.7 ± 0.9) were found in the South China Sea for the first time. The unique restriction polymorphism patterns of three species of Hysterothylacium are provided for rapid diagnosis. Our present results indicate that RFLP analysis of ITS region, using the restriction enzymes HhaI and RsaI, represents a simple and practical method for large-scale surveys of Hysterothylacium for seafood industry.

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The Anthropocene has brought substantial change to ocean ecosystems, but whether this age will bring more or less marine disease is unknown. In recent years, the accelerating tempo of epizootic and zoonotic disease events has made it seem as if disease is on the rise. Is this apparent increase in disease due to increased observation and sampling effort, or to an actual rise in the abundance of parasites and pathogens? We examined the literature to track long-term change in the abundance of two parasitic nematode genera with zoonotic potential: Anisakis spp. and Pseudoterranova spp. These anisakid nematodes cause the disease anisakidosis and are transmitted to humans in undercooked and raw marine seafood. A total of 123 papers published between 1967 and 2017 met our criteria for inclusion, from which we extracted 755 host-parasite-location-year combinations. Of these, 69.7% concerned Anisakis spp. and 30.3% focused on Pseudoterranova spp. Meta-regression revealed an increase in Anisakis spp. abundance (average number of worms/fish) over a 53 year period from 1962 to 2015 and no significant change in Pseudoterranova spp. abundance over a 37 year period from 1978 to 2015. Standardizing changes to the period of 1978-2015, so that results are comparable between genera, we detected a significant 283-fold increase in Anisakis spp. abundance and no change in the abundance of Pseudoterranova spp. This increase in Anisakis spp. abundance may have implications for human health, marine mammal health, and fisheries profitability.

Anisakidosis is an infection caused by larval nematodes that belong to several genera within the family Anisakidae. Anisakidosis has about 20000 cases reported to date, the vast majority (90%) in Japan. Usually, human anisakiosis is more common than human pseudoterranovosis in Japan and Europe, although in North America Pseudoterranova spp. is the more frequent. Cases of human pseudoterranovosis have been reported from Chile and Peru. We here report one of the few cases of human infection by Pseudoterranova cattani by consumption of \"ceviche\" in Buenos Aires, Argentina.

Serodiagnosis of human anisakidosis is presently hampered by the current lack of standardised serological assays that allow sensitive and specific detection of Anisakidae-specific antibodies in human patients. In the present study, we comparatively evaluated the diagnostic value (by IgG-ELISA) of excretory-secretory antigens (ESAgs) of Anisakis simplex, Pseudoterranova decipiens and Contracaecum osculatum, representing the most frequently found genera responsible for human infection. In addition, we tested also a mix of the three ES preparations (Mix-ESAgs) as well as two recombinant allergens of A. simplex, rAni s 1 and rAni s 7. ES antigen from C. osculatum yielded the best diagnostic performance in IgG-ELISA-based serodiagnosis of the Spanish anisakidosis patients investigated in this study (relative serodiagnostic sensitivity 100%; specificity 89%) as compared to A. simplex ES-antigen (93% versus 57%) and P. decipiens (67% versus 93%) or a mix of the three ES antigens (100% versus 44%), respectively. Cross-reactions of C. osculatum ES antigen with serum-antibodies from patients suffering from other helminth infections were rare and were exclusively found with few sera from toxocariasis, ascariasis, and filariasis patients. The two recombinant allergens rAni s 1 and rAni s 7 did not prove sufficiently sensitive and specific in order to justify a further evaluation of these antigens regarding their suitability in IgG-ELISA-based serodiagnosis of human anisakidosis. In conclusion, the C. osculatum-ESAg-ELISA remains as key candidate to be further assessed for the serodiagnosis of symptomatic anisakidosis in different endemic regions.

The risk of infection with Anisakis has been recognized for some time, but it is now emerging due to major awareness, better diagnostic techniques, and increasing preference for raw or lightly cooked food. Spain has the second-highest reported incidence after Japan, though the real anisakidosis burden is unknown because of the scarcity of epidemiological data. This study provides a 19-year review of anisakidosis-related hospitalizations describing epidemiological trends and patient characteristics.
We performed a retrospective descriptive study using the Spanish Hospitalization Minimum Data Set from 1997 to 2015. Hospitalization rates were calculated and spatial distribution of cases and their temporal behavior were assessed. Clinical characteristics were described, including related codiagnoses and procedures.
A total of 2471 hospital discharges were identified. A continuous increasing trend was observed, with several peaks. Most affected communities were located in the northwest inland part of the country. Almost 54% of hospitalized patients were male, with a mean age of 51.3 years. Median length of stay was 5 days, and the hospitalization median cost around €2900. Fatal outcome occurred in 0.5%. Most frequent codiagnoses were digestive diseases, mainly intestinal obstruction. Urticaria, anaphylactic reaction, and angioneurotic edema were only recorded in 2.2%, 2.4%, and 1.2%, respectively.
Knowing that hospitalization is unusual in anisakidosis, we offer calculations of the real disease burden. Improving disease surveillance in parallel to disease control will be useful both in gaining extended disease knowledge and reducing morbidity and related costs.

Australia is a multicultural country surrounded by water where seafood is regularly consumed. Literature suggests that some popular edible fish sold in fish markets may be infected with parasites transmissible to humans (notably, anisakids and other helminths); however the number of reported human cases due to these parasites is low. In this article we critically review topical publications to understand whether the low number of human infection is due to lack of expertise in Australia to identify and diagnose accurately seafood-borne parasitic infections. The risk these parasites pose to humans may be underestimated due to: (i) errors or inability of diagnosing these infections, primarily due to less sensitive and specific serological tests and misidentifying parasites without a taxonomist in the diagnostic team; and (ii) medical practitioners not being aware of these parasites or not considering them in the differential diagnosis even in patients with history of regular raw or undercooked seafood consumption.