A case of anisakidosis caused by Pseudoterranova decipiens larva

A critical review of anisakidosis cases occurring globally

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.

Seals, fish, humans and parasites in the Baltic: ecology, evolution and history

Evolutionary and ecological processes affecting the interactions between hosts and parasites in the aquatic environment are at display in the Baltic Sea, a young and ecologically unstable marine ecosystem, where fluctuating abiotic and biotic factors affect the parasitofauna in fish. The dynamic infections of Baltic cod, a subpopulation of the Atlantic cod (Gadus morhua Linnaeus), with third stage anisakid nematode larvae of Pseudoterranova decipiens (Krabbe, 1878) and Contracaecum osculatum (Rudolphi, 1802) have increased following a significant increase of the Baltic grey seal Halichoerus grypus (Fabricius) population in the region. Cod serves as a paratenic host and marine mammals, pinnipeds, are definitive hosts releasing parasite eggs, with faeces, to the marine environment, where embryonation and hatching of the third stage larva take place. The parasite has no obligate intermediate hosts, but various invertebrates, smaller fish and cod act as paratenic hosts transmitting the infection to the seal. Contracaecum osculatum has an impact on the physiological performance of the cod, which optimises transmission of the larva from fish to seal. Thus, a muscle mass decrease of nearly 50% may result from heavy C. osculatum infections, probably amplified by a restricted food availability. The muscle atrophy is likely to reduce the escape reactions of the fish when meeting a foraging seal. In certain regions, where fish and seals are restricted in their migration patterns, such as the semi-enclosed Baltic Sea, the predation may contribute to a severe cod stock depletion. The parasites are zoonotic and represent a human health risk, when consumers ingest insufficiently heat- or freeze-treated infected products. Marked infections of the cod were previously reported during periods with elevated seal populations (late 19th and middle 20th century) and various scenarios for management of risk factors are evaluated in an evolutionary context.

Nasal localization of a Pseudoterranova decipiens larva in a Danish patient with suspected allergic rhinitis

Pseudoterranoviasis is a zoonotic disease caused by nematode larvae of species within the genus Pseudoterranova (seal worm, cod worm). Most infections are gastrointestinal, oesophageal or pharyngeal, but here we report a nasal infection. A 33-year-old patient suffering from rhinitis for 1.5 years recovered a worm larva from the nose. Diagnosis was performed by morphological and molecular characterization, showing the causative agent to be a third-stage larva of Pseudoterranova decipiens (sensu stricto). Various infection routes are discussed.

Extra-gastrointestinal anisakidosis caused by Pseudoterranova azarasi manifesting as strangulated inguinal hernia

The incidence of anisakidosis continues to increase worldwide due to increased consumption of undercooked fish. Although anisakidosis can be categorized into four clinical phenotypes (gastric, intestinal, ectopic, and allergic), ectopic forms of the condition are much less common than gastric or intestinal forms when caused by Pseudoterranova spp. We report the case of a 5-year-old patient who presented with a rapidly growing left inguinal mass and was subsequently diagnosed with extra-gastrointestinal anisakidosis caused by Pseudoterranova azarasi.

Epicutaneous sensitization with nematode antigens of fish parasites results in the production of specific IgG and IgE

Fish consumption plays an important role in the human diet.Hoplias malabaricus, trahira, is a freshwater fish widely appreciated in several Brazilian states and it is frequently infected byContracaecum multipapillatumthird-instar larvae (L3). The aim of the present study was to evaluate the allergenic potential of theC. multipapillatumL3 crude extract (CECM). BALB/c mice were immunized intraperitoneally (ip) with 10 or 50 μg CECM associated with 2 mg of aluminium hydroxide on days 0, 14 and 48. The determination of specific IgG and IgE antibody levels was done after immunization, and the late immunity was evaluated by the intradermal reaction in the ear pavilion. Epicutaneous sensitization was performed in the dorsal region, with antigenic exposure via a Finn-type chamber, containing 100 μg of chicken ovum albumin (OVA) or 100 μg CECM. After the exposures, the specific antibody levels were determined. In the ip immunization, there was a gradual increase in IgG antibody levels, independent of CECM concentration. In relation to IgE production, it was transitory, and immunization with 10 μg was more efficient than that of 50 μg. The same result was observed in the cellular hypersensitivity reaction. In the case of antigen exposure by the epicutaneous route, it was verified that only CECM was able to induce detectable levels of specific IgG and IgE antibodies. In the present study it was demonstrated that both intraperitoneal immunization and epicutaneous contact withC. multipapillatumlarval antigens are potentially capable of inducing allergic sensitization in mice.

Morphological and molecular diagnosis of Pseudoterranova decipiens (sensu stricto) (Anisakidae) in imported cod sold in Brazil

An anisakid nematode larva found in cod sold in the state of Minas Gerais, Brazil was studied by light and scanning electron microscopy and by a molecular approach. Mitochondrial cytochrome c-oxidase subunit 2 (mtDNA cox-2), 28S rRNA and ITS1, 5.8S and ITS2 regions were amplified using the polymerase chain reaction and sequenced to evaluate the phylogenetic relationships of the larva. The genetic profile confirmed that this larva belongs to the species Pseudoterranova decipiens (sensu stricto). This is the first molecular and ultrastructural study of Pseudoterranova decipiens (sensu stricto) in imported cod sold in Brazil. The health implications of these findings are discussed.

Excretory/secretory products of anisakid nematodes: biological and pathological roles

Parasites from the family Anisakidae are widely distributed in marine fish populations worldwide and mainly nematodes of the three genera Anisakis, Pseudoterranova and Contracaecum have attracted attention due to their pathogenicity in humans. Their life cycles include invertebrates and fish as intermediate or transport hosts and mammals or birds as final hosts. Human consumption of raw or underprocessed seafood containing third stage larvae of anisakid parasites may elicit a gastrointestinal disease (anisakidosis) and allergic responses. Excretory and secretory (ES) compounds produced by the parasites are assumed to be key players in clinical manifestation of the disease in humans, but the molecules are likely to play a general biological role in invertebrates and lower vertebrates as well. ES products have several functions during infection, e.g. penetration of host tissues and evasion of host immune responses, but are at the same time known to elicit immune responses (including antibody production) both in fish and mammals. ES proteins from anisakid nematodes, in particular Anisakis simplex, are currently applied for diagnostic purposes but recent evidence suggests that they also may have a therapeutic potential in immune-related diseases.

Molecular diagnosis of Pseudoterranova decipiens s.s in human, France

Background

Anisakis and Pseudoterranova are the main genera involved in human infections caused by nematodes of the Anisakidae family. Species identification is complicated due to the lack of differential morphological characteristics at the larval stage, thus requiring molecular differentiation. Pseudoterranova larvae ingested through raw fish are spontaneously eliminated in most cases, but mechanical removal by means of endoscopy might be required. To date, only very few cases of Pseudoterranova infection have been reported in France.

Case presentation

A 19-year-old woman from Northeastern France detected, while brushing her teeth, a larva exiting through her mouth. The patient who presented with headache, diarrhea, and abdominal cramps reported having eaten baked cod. The worm was a fourth-stage larva with a size of 22 × 0.9 mm, and molecular biology identified it as Pseudoterranova decipiens sensu stricto (s. s.). In a second P. decipiens infection case, occurring a few months later, a worm exited through the patient’s nose after she had eaten raw sea bream.

Conclusion

These two cases demonstrate that Pseudoterranova infection is not uncommon among French patients. Therefore, molecular techniques should be more widely applied for a better characterization of anisakidosis epidemiology in France.

First case report of invasive pseudoterranoviasis in Italy

Members of the genera Anisakis and Pseudoterranova are the main causative agents of human anisakidosis: the disease is worldwide distributed, with major impact in countries with a large consumption of raw fish. Because of unspecific symptoms and limited diagnostic tools, incidence and burden of disease are probably underestimated. In Italy, all human infestations where the etiological agent has been properly identified, have been associated to the parasitic species Anisakis pegreffii, the most frequent anisakid in the Mediterranean area. Here, an invasive human case of pseudoterranoviasis is described for the first time in Italy: in 2015, a woman was found infected during a colonoscopy scheduled after the occurrence of nonspecific clinical symptoms. The nematode was found penetrating the ascending colon. The identification was performed by sequencing the mitochondrial region cox2 and by comparison to GenBank retrieved material using the BLAST search tool. The sample showed a 99% identity with Pseudoterranova decipiens sensu stricto. The record underlines the potential risk due to the consumption of raw or undercooked imported fishes.

Anisakiasis: Report of 15 Gastric Cases Caused by Anisakis Type I Larvae and a Brief Review of Korean Anisakiasis Cases

The present study was performed to report 15 anisakiasis cases in Korea and to review the Korean cases reported in the literature. Total 32 Anisakis type I larvae were detected in the stomach of 15 patients by the endoscopy. Single worm was detected from 12 cases, and even 9 larvae were found from 2 cases. Epigastric pain was most commonly manifested in almost all cases, and hemoptysis and hematemesis were seen in 1 case each. Symptom manifestations began at 10-12 hr after eating fish in 73.3% cases. Endoscopy was performed 1-2 days after the symptom onset in most cases. The common conger, Conger myriaster, was the probable infection source in 7 cases. In the review of Korean anisakiasis cases, thus far, total 645 cases have been reported in 64 articles. Anisakis type I larva was the most frequently detected (81.3%). The favorable infection site of larvae was the stomach (82.4%). The common conger was the most probable source of human infections (38.6%). Among the total 404 cases which revealed the age and sex of patients, 185 (45.8%) were males, and the remaining 219 (54.2%) were female patients. The age prevalence was the highest in forties (34.7%). The seasonal prevalence was highest in winter (38.8%). By the present study, 15 cases of gastric anisakiasis are added as Korean cases, and some epidemiological characteristics of Korean anisakiasis were clarified.