ß Pore-forming Protein-based Evolutionary Divergence of Gnathostomata from Agnatha.

INTRODUCTION: The first vertebrates were jawless fish, or Agnatha, whose evolution diverged into jawed fish, or Gnathostomes, around 550 million years ago. METHODS: In this study, we investigated ß PFT proteins' evolutionary divergence of lamprey immune protein from Agnatha, reportedly possessing anti-cancer activity, into Dln1 protein from Gnathostomes. Both proteins showed structural and functional divergence, and shared evolutionary origin. Primary, secondary and tertiary sequences were compared to discover functional domains and conserved motifs in order to study the evolution of these two proteins. The structural and functional information relevant to evolutionary divergence was revealed using hydrophobic cluster analysis. RESULTS: The findings demonstrate that two membrane proteins with only a small degree of sequence identity can have remarkably similar hydropathy profiles, pointing towards conserved and similar global structures. When facing the lipid bilayer or lining the pore lumen, the two proteins' aerolysin domains' corresponding residues displayed a similar and largely conserved pattern. Aerolysin-like proteins from different species can be identified using a fingerprint created by PIPSA analysis of the pore-forming protein. CONCLUSION: We were able to fully understand the mechanism of action during pore formation through structural studies of these proteins.

PML and PML-like exonucleases restrict retrotransposons in jawed vertebrates.

We have uncovered a role for the promyelocytic leukemia (PML) gene and novel PML-like DEDDh exonucleases in the maintenance of genome stability through the restriction of LINE-1 (L1) retrotransposition in jawed vertebrates. Although the mammalian PML protein forms nuclear bodies, we found that the spotted gar PML ortholog and related proteins in fish function as cytoplasmic DEDDh exonucleases. In contrast, PML proteins from amniote species localized both to the cytoplasm and formed nuclear bodies. We also identified the PML-like exon 9 (Plex9) genes in teleost fishes that encode exonucleases. Plex9 proteins resemble TREX1 but are unique from the TREX family and share homology to gar PML. We also characterized the molecular evolution of TREX1 and the first non-mammalian TREX1 homologs in axolotl. In an example of convergent evolution and akin to TREX1, gar PML and zebrafish Plex9 proteins suppressed L1 retrotransposition and could complement TREX1 knockout in mammalian cells. Following export to the cytoplasm, the human PML-I isoform also restricted L1 through its conserved C-terminus by enhancing ORF1p degradation through the ubiquitin-proteasome system. Thus, PML first emerged as a cytoplasmic suppressor of retroelements, and this function is retained in amniotes despite its new role in the assembly of nuclear bodies.

Evaluation of Rapid IgG4 Test for Diagnosis of Gnathostomiasis.

Human gnathostomiasis is a parasitic disease caused by Gnathostoma nematode infection. A rapid, reliable, and practical immunoassay, named dot immuno-gold filtration assay (DIGFA), was developed to supporting clinical diagnosis of gnathostomiasis. The practical tool detected anti-Gnathostoma-specific IgG4 in human serum using crude extract of third-stage larvae as antigen. The result of the test was shown by anti-human IgG4 monoclonal antibody conjugated colloidal gold. The sensitivity and specificity of the test were both 100% for detection in human sera from patients with gnathostomiasis (13/13) and from healthy negative controls (50/50), respectively. Cross-reactivity with heterogonous serum samples from patients with other helminthiases ranged from 0 (trichinosis, paragonimiasis, clonorchiasis, schistosomiasis, and cysticercosis) to 25.0% (sparganosis), with an average of 6.3% (7/112). Moreover, specific IgG4 antibodies diminished at 6 months after treatment. This study showed that DIGFA for the detection of specific IgG4 in human sera could be a promising tool for the diagnosis of gnathostomiasis and useful for evaluating therapeutic effects.

An Unusual Case of Gastric Gnathostomiasis Caused by Gnathostoma spinigerum Confirmed by Video Gastroscopy and Morphological and Molecular Identification.

Human gnathostomiasis is a harmful foodborne parasitic infection caused by nematodes of the genus Gnathostoma. Here, we report an unusual case of gastric gnathostomiasis seen in a hospital in Thailand along with the clinical characteristics, treatment, and outcome. A 39-year-old man presented with complaints of epigastric pain, dizziness, and history of passing dark, tarry stools for 2 days. The patient had a history of consuming raw freshwater fish. Supplementary differential diagnosis was performed via rapid serological testing, and presence of the causative agent was confirmed based on video gastroscopy, morphology of the removed parasite, and molecular identification. After its surgical removal from the stomach, the parasite was morphologically identified as Gnathostoma species. Molecular identification was performed via DNA extraction from the recovered worm, and amplification and sequencing of the second internal transcribed spacer (ITS2) region and partial cytochrome c oxidase subunit I (cox1) gene. The ITS2 and cox1 sequences were consistent with those of Gnathostoma spinigerum. Clinicians in endemic areas should therefore be aware of the rare clinical manifestations and use of supplementary serological tests to facilitate early diagnosis and treatment of gastric gnathostomiasis.

Gnathostomiasis acquired after consumption of raw freshwater fish in the Amazon region: a report of two cases in Brazil

Abstract Gnathostomiasis is a parasitic zoonosis caused by the helminth Gnathostoma spp., acquired through the consumption of raw or undercooked contaminated aquatic animals.The disease is endemic in Southeast Asia and Central America. Two male patients, both middle-aged, presented with single itchy erythemato-edematous plaques on the anterior thorax and left flank. Both had consumed raw fish in the Amazon region. The clinical and epidemiological examinations suggested gnathostomiasis, and treatment with albendazole caused total regression of the lesions. Health teams should be familiar with the disease to provide correct diagnosis. The control strategy should be based on health education for the population.

Case Report: The First Direct Evidence of Gnathostoma spinigerum Migration through Human Lung.

Gnathostomiasis is a helminthic infection caused by the third-stage larvae of nematodes of the genus Gnathostoma. The life cycle in humans starts with an enteric phase, with the worm perforating the gastric or intestinal mucosa to reach the peritoneal cavity and migrating through the human body. Subsequent penetration through the diaphragm may produce pleuropulmonary symptoms. We herein present a previously healthy 56-year-old Thai man from Southern Thailand who was an ex-smoker presented with chronic dry cough progressing to hemoptysis after consuming grilled swamp eels and freshwater fish. Chest computed tomography showed consolidation at the lingular segment, and the differential diagnosis was primary lung cancer and pulmonary tuberculosis. The lung tissue biopsied during bronchoscopy displayed segments of organisms with the phenotypic characteristics of Gnathostoma spp., and abundant eosinophils were seen in the alveolar tissue. Gnathostoma spinigerum infection was confirmed by a Western blot assay for G. spinigerum-specific 24-kDa reactive band. The patient received albendazole, and a follow-up chest radiograph revealed improvement in the consolidation in the lung and reduction in hemoptysis. We report the first direct evidence including pathology and immunohistochemistry of Gnathostoma invasion via the human lung, with clinical and radiographic presentations mimicking either malignancy or chronic infection.

Molecular Identification of the Etiological Agent of Human Gnathostomiasis in an Endemic Area of Mexico.

Human gnathostomiasis, which is endemic in Mexico, is a worldwide health concern. It is mainly caused by the consumption of raw or insufficiently cooked fish containing the advanced third-stage larvae (AL3A) of Gnathostoma species. The diagnosis of gnathostomiasis is based on epidemiological surveys and immunological diagnostic tests. When a larva is recovered, the species can be identified by molecular techniques. Polymerase chain reaction (PCR) amplification of the second internal transcription spacer (ITS-2) is useful to identify nematode species, including Gnathostoma species. This study aims to develop a duplex-PCR amplification method of the ITS-2 region to differentiate between the Gnathostoma binucleatum and G. turgidum parasites that coexist in the same endemic area, as well as to identify the Gnathostoma larvae recovered from the biopsies of two gnathostomiasis patients from Sinaloa, Mexico. The duplex PCR established based on the ITS-2 sequence showed that the length of the amplicons was 321 bp for G. binucleatum and 226 bp for G. turgidum. The amplicons from the AL3A of both patients were 321 bp. Furthermore, the length and composition of these amplicons were identical to those deposited in GenBank as G. binucleatum (accession No. JF919679), corroborating our previous morphological finding that G. binucleatum is the etiological agent for human gnathostomiasis in the endemic area of Sinaloa, Mexico.

Vulvitis migratoria causada por gnatostomiasis importada / Migratory vulvitis caused by imported gnathostomiasis

Resumen La gnatostomiasis es una parasitosis emergente en países no endémicos. Este nematodo zoonótico requiere de agua dulce para su ciclo de vida, donde sus larvas se enquistan principalmente en peces. La migración subcutánea de las larvas produce habitualmente una paniculitis eosinofílica de rápido avance. Se describe un caso clínico de un paciente con una lesión migratoria, sin mejoría clínica con terapia antibacteriana. La búsqueda de factores de riesgo, sumado a la evolución y a los hallazgos de laboratorio hizo sospechar el diagnóstico. La gnatostomiasis debe ser sospechado en pacientes con lesiones de piel migratorias, que han consumido pescado crudo durante viajes a países endémicos en Sudamérica o Asia.

Gnathostomiasis is an emerging disease in non-endemic countries. This zoonotic nematode requires aquatic freshwater environments to complete its life cycle where larvae get encrusted in fishes. Typically, the infection manifests as migratory subcutaneous lesion caused by the larvae trak, which produces an eosinophilic panniculitis. Here we describe a patient who presented a migratory lesion with no response to antimicrobial therapy, a careful travel and food history together with specific laboratory tests led to the correct diagnosis. Gnathostomiasis should be suspected in patients with migratory skin lesions who have consumed raw freshwater fish during travel to endemic countries in South America or Asia.

Gnathostomiasis: an emerging infectious disease relevant to all dermatologists.

Gnathostomiasis is a parasitic infection caused by the third larval stage of nematodes of the genus Gnathostoma. The disease is endemic in some countries around the world. In the American continent, the majority of cases is concentrated in Mexico, Ecuador, and Peru. However, due to increasing traveling either at the intercontinental or intracontinental level, the disease is seen each time more frequently in tourists. Furthermore, countries, such as Brazil, that have never been considered endemic are reporting autochthonous cases. The disease usually presents as a deep-seated or slightly superficial migratory nodule in patients with history of eating raw fish, in the form of ceviche, sushi, or sashimi. Along with the clinical presentation, diagnostic criteria include either blood or tissue eosinophilia. In most instances, these criteria are enough for the attending physician to institute therapy. Chances of finding the parasite are low, unless the biopsy is taken from a very specific area that develops after antiparasitic treatment is started. The potential of other organ involvement with more serious consequences should always be kept in mind.

Gnathostomiasis: an emerging infectious disease relevant to all dermatologists

Abstract: Gnathostomiasis is a parasitic infection caused by the third larval stage of nematodes of the genus Gnathostoma. The disease is endemic in some countries around the world. In the American continent, the majority of cases is concentrated in Mexico, Ecuador, and Peru. However, due to increasing traveling either at the intercontinental or intracontinental level, the disease is seen each time more frequently in tourists. Furthermore, countries, such as Brazil, that have never been considered endemic are reporting autochthonous cases. The disease usually presents as a deep-seated or slightly superficial migratory nodule in patients with history of eating raw fish, in the form of ceviche, sushi, or sashimi. Along with the clinical presentation, diagnostic criteria include either blood or tissue eosinophilia. In most instances, these criteria are enough for the attending physician to institute therapy. Chances of finding the parasite are low, unless the biopsy is taken from a very specific area that develops after antiparasitic treatment is started. The potential of other organ involvement with more serious consequences should always be kept in mind.

Cloning and expression of a 16-kDa recombinant protein from Angiostrongylus cantonensis for use in immunoblot diagnosis of human angiostrongyliasis.

Angistrongylus cantonensis is a zoonotic nematode parasite and causative agent of human angiostrongyliasis, which clinically presents as eosinophilic meningitis or meningoencephalitis. Diagnosis of the disease is problematic since parasitologic findings are infrequent, and infection determinations must be based on the clinical symptoms and serological tests with limited specificities and sensitivities. The aim of the present study was to identify and generate a novel recombinant protein from A. cantonensis and evaluate its efficacy in the diagnosis of human angiostrongyliasis when incorporated into a Western blot serodiagnostic system. A cDNA protein expression library from adult A. cantonensis was constructed, followed by immunoscreening with serum from confirmed infected patients to identify and isolate immunoreactive clones. One clone, designated fAC40, possessed a partial sequence encoding a LisH protein domain with a predicted molecular weight of 16 kDa and containing four predicted antigenic peptides. By incorporating recombinant fAC40 in Western immunoblot tests using a serum panel consisting of confirmed and clinically diagnosed cases of human angiostrongyliasis and other helminthic infections, fAC40 exhibited a sensitivity and specificity of 91.8 and 100 %, respectively, and a positive and negative predictive value of 100 and 97.19 %, respectively, in the diagnosis of angiostrongyliasis. Importantly, it was not reactive with antibodies from serum of patients infected with Gnathostoma spinigerum and Cysticercus cellulosae, infections that clinically present neurological symptoms similar to angiostrongyliasis. These data demonstrate that the 16-kDa recombinant protein from A. cantonensis possesses high potential as a candidate antigen for a more sensitive and specific serodiagnosis of human angiostrongyliasis.

Gnatostomiasis cutánea, primer caso confirmado en Colombia / Cutaneous gnathostomiasis, first confirmed case in Colombia

La gnatostomiasis es una zoonosis parasitaria causada por algunas especies del género de helmintos Gnathostoma . La presentación clínica es muy variada y su diagnóstico constituye un desafío; es endémica en países tropicales y subtropicales, y la transmisión se asocia con el consumo de carne de animales acuáticos, cruda o mal cocida. En las últimas décadas, el creciente turismo internacional y el consumo de alimentos exóticos, han provocado un notable aumento de casos de la enfermedad. En nuestro país no se ha reportado ningún caso confirmado de gnatostomiasis. Se presenta el caso de un hombre colombiano de 63 años de edad, viajero frecuente al exterior, que consultó por presentar síntomas gastrointestinales. Durante la hospitalización desarrolló una lesión cutánea en el flanco abdominal derecho, de la cual se extrajo una larva cuya descripción morfológica permitió clasificarla como Gnathostoma spinigerum . Se trata de la primera confirmación de un caso importado de gnatostomiasis en Colombia. En este artículo se discuten las generalidades, la etiología, la patogenia y el tratamiento de la enfermedad, con especial énfasis en las características particulares de este paciente.

Gnathostomiasis is a parasitic zoonosis caused by some species of helminthes belonging to the genus Gnathostoma . It has a wide clinical presentation and its diagnosis is a challenge. Tropical and subtropical countries are endemic, and its transmission is associated with eating raw or undercooked meat from fresh water animals. Increasing global tourism and consuming exotic foods have produced a noticeable rise in cases of the disease in the last decades. However, in our country, there has not been any confirmed case of gnathostomiasis previously reported. We present the case of a 63-year-old Colombian man with an international travel history, who presented with gastrointestinal symptoms. During the hospital stay, he developed a cutaneous lesion on the upper right abdominal quadrant, where later, a larva was found. A morphological study allowed us to identify it as Gnathostoma spinigerum . As such, this is the first report of an imported case of gnathostomiasis confirmed in Colombia. This article describes the principles, etiology, pathogenic cycle and treatment of this disease with special considerations to our patient´s particular features.

[Foodborne dermatosis after traveling: gnathostomiasis]. / Dermatosis de origen alimentario al regreso de un viaje: gnathostomiasis.

We describe a case of a 32-year-old man, resident in Buenos Aires, with dermatologic manifestations compatible with gnathostomiasis. The patient had traveled to Colombia in the month prior to the onset of symptoms. There, he repeatedly ate ceviche (raw fish marinated in lemon juice). He presented with an erythematous migratory panniculitis accompanied by eosinophilia. He underwent skin biopsy of a lesion and pathological diagnosis was "eosinophilic panniculitis". The triad of migratory panniculitis, eosinophilia and consume of raw fish during the trip to Colombia was suggestive of gnathostomiasis. Ivermectin treatment started out with good initial response but subsequent relapse. We performed a new treatment with the same drug with good results and no relapses during three years of follow up. The dermatological disease is common upon return from a trip, and is the third leading cause of morbidity in travelers. It is very important to recognize cutaneous manifestations of disease as many of them are potentially serious and may compromise the patient's life if not promptly diagnosed and treated.

Dermatosis de origen alimentario al regreso de un viaje: gnathostomiasis / Foodborne dermatosis after traveling: gnathostomiasis

Se describe el caso de un paciente de 32 años de edad, residente en Buenos Aires, con manifestaciones dermatológicas compatibles con gnathostomiasis. Había realizado un viaje a Colombia en el mes previo a la aparición de la sintomatología. Allí consumió cebiche (pescado crudo marinado en jugo de limón) en reiteradas oportunidades. El cuadro clínico se presentó como paniculitis eritematosa y migratoria acompañada de eosinofilia sanguínea. Se le realizó biopsia cutánea de una lesión y el diagnóstico anatomopatológico fue "paniculitis eosinofílica". La tríada de paniculitis migratoria, eosinofilia sanguínea y el consumo de pescado crudo durante el viaje a Colombia fue sugestiva de gnathostomiasis por lo que se indicó tratamiento con ivermectina con buena evolución inicial y recaída posterior. Se realizó un nuevo tratamiento con la misma droga con buena evolución y sin recaídas durante tres años de seguimiento. La afección dermatológica es un motivo frecuente de consulta al regreso de un viaje, y representa la tercera causa de morbilidad en viajeros. Es muy importante el reconocimiento de las enfermedades que pueden tener manifestación cutánea, ya que muchas de ellas son potencialmente graves y pueden poner en riesgo la vida del paciente si no son oportunamente diagnosticadas y tratadas.

We describe a case of a 32-year-old man, resident in Buenos Aires, with dermatologic manifestations compatible with gnathostomiasis. The patient had traveled to Colombia in the month prior to the onset of symptoms. There, he repeatedly ate ceviche (raw fish marinated in lemon juice). He presented with an erythematous migratory panniculitis accompanied by eosinophilia. He underwent skin biopsy of a lesion and pathological diagnosis was "eosinophilic panniculitis". The triad of migratory panniculitis, eosinophilia and consume of raw fish during the trip to Colombia was suggestive of gnathostomiasis. Ivermectin treatment started out with good initial response but subsequent relapse. We performed a new treatment with the same drug with good results and no relapses during three years of follow up. The dermatological disease is common upon return from a trip, and is the third leading cause of morbidity in travelers. It is very important to recognize cutaneous manifestations of disease as many of them are potentially serious and may compromise the patient's life if not promptly diagnosed and treated.

Cutaneous gnathostomiasis with recurrent migratory nodule and persistent eosinophilia: a case report from China.

The present study reports a human case of cutaneous gnathostomiasis with recurrent migratory nodule and persistent eosinophilia in China. A 52-year-old woman from Henan Province, central China, presented with recurrent migratory reddish swelling and subcutaneous nodule in the left upper arm and on the back for 3 months. Blood examination showed eosinophila (21.2%), and anti-sparganum antibodies were positive. Skin biopsy of the lesion and histopathological examinations revealed dermal infiltrates of eosinophils but did not show any parasites. Thus, the patient was first diagnosed as sparganosis; however, new migratory swellings occurred after treatment with praziquantel for 3 days. On further inquiring, she recalled having eaten undercooked eels and specific antibodies to the larvae of Gnathostoma spinigerum were detected. The patient was definitely diagnosed as cutaneous gnathostomiasis caused by Gnathostoma sp. and treated with albendazole (1,000 mg/day) for 15 days, and the subsequent papule and blister developed after the treatment. After 1 month, laboratory findings indicated a reduced eosinophil count (3.3%). At her final follow-up 18 months later, the patient had no further symptoms and anti-Gnathostoma antibodies became negative. Conclusively, the present study is the first report on a human case of cutaneous gnathostomiasis in Henan Province, China, based on the past history (eating undercooked eels), clinical manifestations (migratory subcutaneous nodule and persistent eosinophilia), and a serological finding (positive for specific anti-Gnathostoma antibodies).

Gnathostoma spinigerum infection in the upper lip of a Korean woman: an autochthonous case in Korea.

Autochthonous human gnathostomiasis had never been reported in the Republic of Korea. We report here a case of Gnathostoma spinigerum infection in a 32-year-old Korean woman, presumed to have been infected via an indigenous route. The patient had experienced a painful migratory swelling near the left nasolabial fold area of the face for a year, with movement of the swelling to the mucosal area of the upper lip 2 weeks before surgical removal of the lesion. Histopathological examinations of the extracted tissue revealed inflammation with heavy eosinophilic infiltrations and sections of a nematode suggestive of a Gnathostoma sp. larva. The larva characteristically revealed about 25 intestinal cells with multiple (3-6) nuclei in each intestinal cell consistent with the 3rd-stage larva of G. spinigerum. The patient did not have any special history of travel abroad except a recent trip, 4 months before surgery, to China where she ate only cooked food. The patient is the first recorded autochthonous case of G. spinigerum infection in Korea.

Gnathostoma spinigerum: immunodepression in experimental infected mice.

Mice were infected with 8- or 25-infective worms of advanced third stage Gnathostoma spinigerum larvae (L3) which were obtained from natural infected eels. On day 14, 60 and 200 post infections (PI), spleen cells of infected mice were tested for lymphoproliferative responses in vitro against the mitogen and specific L3 somatic antigen in order to clarify the cellular immune status of the host upon this nematode infection. Reduced responsiveness to Con A was observed in infected mice. These depressed responses were more pronounced in chronically infected mice (day 200, PI) than in day 14 and day 60, PI. There was no significant difference of lymphoproliferative response between groups of high (25 L3) and low (8 L3)-infective dose in the chronic readily stage. Regarding to the L3 somatic Ag stimulation, the depressed response was obviously detected in high dose and chronic infection. Our results demonstrated that in this G. spinigerum-mouse system T-cell response is defective. The depression could be reversible and was associated with active infection because it was abolished by anthelmintic (ivermectin) treatment. This study shows the involvement of Th-2 response to this nematode in regulating T cell proliferation.

Identification of immunodominant peptides from Gnathostoma binucleatum.

Gnathostomiasis is now recognized as a zoonosis with a worldwide distribution. In the Americas, it is caused by the third-stage larvae of Gnathostoma binucleatum and in Asia mainly by G. spinigerum. The availability and preparation of specific antigens are among the main obstacles for developing reliable immunodiagnostic tests. In this study, six immunodominant peptides were identified and characterized from G. binucleatum, somatic antigens (AgS: 24, 32, and 40 kDa) and excretory-secretory antigens (AgES: 42, 44, and 56 kDa) by two-dimensional immunoblot analysis. Among those immunodominant peptides, two AgS spots were characterized by mass spectrometric analysis (32 kDa; pI 6.3 and 6.5) and identified as type 1 galectins. In accordance with this finding, a fraction of AgS exhibited affinity to lactose and displayed a 100% specificity and sensitivity for the diagnosis of human gnathostomiasis.

Evolution of the let-7 microRNA family.

The increase of bodyplan complexity in early bilaterian evolution is correlates with the advent and diversification of microRNAs. These small RNAs guide animal development by regulating temporal transitions in gene expression involved in cell fate choices and transitions between pluripotency and differentiation. One of the two known microRNAs whose origins date back before the bilaterian ancestor is mir-100. In Bilateria, it appears stably associated in polycistronic transcripts with let-7 and mir-125, two key regulators of development. In vertebrates, these three microRNA families have expanded to form a complex system of developmental regulators. In this contribution, we disentangle the evolutionary history of the let-7 locus, which was restructured independently in nematodes, platyhelminths, and deuterostomes. The foundation of a second let-7 locus in the common ancestor of vertebrates and urochordates predates the vertebrate-specific genome duplications, which then caused a rapid expansion of the let-7 family.

The Jeju weasel, Mustela sibilica quelpartis, a new definitive host for Gnathostoma nipponicum Yamaguti, 1941.

Adult gnathostomes were discovered in the stomach of the Jeju weasel, Mustela sibilica quelpartis, road-killed in Jeju-do (Province). Their morphological characters were examined to identify the species. Total 50 gnathostome adults were collected from 6 out of 10 weasels examined. In infected weasels, 4-6 worms were grouped and embedded in each granulomatous gastric tumor, except 1 weasel. Male worms were 25.0×1.4 mm in average size, and had a tail with pedunculate papillae, a spicule, and minute tegumental spines. Females were 40.0×2.5 mm in average size, and had a tail without tegumental spines. Pointed and posteriorly curved hooklets were arranged in 8-10 rows on the head bulb. Tegumental spines were distributed from behind the head bulb to the middle portion of the body. The spines were different in size and shape by the distribution level of the body surface. Fertilized eggs were 65.5×38.9 µm in average size, and had a mucoid plug at 1 pole. These gnathostomes from Jeju weasels were identified as Gnathostoma nipponicum Yamaguti, 1941. By the present study, it was confirmed for the first time that G. nipponicum is distributed in Jeju-do, the Republic of Korea, and the Jeju weasel, M. sibilica quelpartis, plays a crucial role for its definitive host.