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

A case of vocal cord gnathostomiasis diagnosed with sectional morphologies in a histopathological specimen from a Chinese woman living in Korea

This study aimed to describe a rare case of gnathostomiasis in the vocal cord. A 54-year-old Chinese woman living in Korea visited with a chief complaint of voice change at the outpatient department of otorhinolaryngology in Hallym Sacred Heart Hospital, Hallym University on August 2, 2021. She had eaten raw conger a few weeks before the voice change developed, but her medical history and physical examinations demonstrated neither gastrointestinal symptoms nor other health problems. A round and red cystic lesion, recognized in the anterior part of the right vocal cord, was removed using forceps and scissors through laryngeal microsurgery. The histopathological specimen of the cyst revealed 3 cross-sections of a nematode larva in the lumen of the cyst wall composed of inflammatory cells and fibrotic tissues. They differ in diameter, from 190 μm to 235 μm. They showed characteristic cuticular layers with tegumental spines, somatic muscle layers, and gastrointestinal tracts such as the esophagus and intestine. Notably, intestinal sections consisted of 27-28 lining cells containing 0-4 nuclei per cell. We tentatively identified the nematode larva recovered from the vocal cord cystic lesion as the third-stage larva of Gnathostoma, probably G. nipponicum or G. hispidum, based on the sectional morphologies.

Morphological and Phylogenetic Analysis of Eustrongylides sp. and Gnathostoma spinigerum Parasitizing the Asian Swamp Eel Monopterusalbus in China

Nematode infections transmitted to humans by the consumption of wild or cultured eels are increasingly being reported. In the present study, 120 Asian swamp eel, Monopterus albus (Zuiew), individuals collected from China were examined for parasite infections, and 78 larval nematodes were isolated. Morphological and molecular characteristics, including sequence and phylogenetic analysis of the internal transcribed spacer (ITS) and cytochrome c oxidase subunit I (COI) gene regions, were employed to identify these nematodes at the lowest taxonomic level possible. Asian swamp eel was infected with two zoonotic parasite taxa: Gnathostoma spinigerum advanced third-stage larvae, with 6.67% prevalence and mean intensity = 1.25, and Eustrongylides sp. fourth-stage larvae, with 26.67% prevalence and mean intensity = 2.13. These findings evidence the need to enhance public hygiene and food safety awareness toward eel consumption.

Human gnathostomiasis: a neglected food-borne zoonosis

BACKGROUND

Human gnathostomiasis is a food-borne zoonosis. Its etiological agents are the third-stage larvae of Gnathostoma spp. Human gnathostomiasis is often reported in developing countries, but it is also an emerging disease in developed countries in non-endemic areas. The recent surge in cases of human gnathostomiasis is mainly due to the increasing consumption of raw freshwater fish, amphibians, and reptiles.

METHODS

This article reviews the literature on Gnathostoma spp. and the disease that these parasites cause in humans. We review the literature on the life cycle and pathogenesis of these parasites, the clinical features, epidemiology, diagnosis, treatment, control, and new molecular findings on human gnathostomiasis, and social-ecological factors related to the transmission of this disease.

CONCLUSIONS

The information presented provides an impetus for studying the parasite biology and host immunity. It is urgently needed to develop a quick and sensitive diagnosis and to develop an effective regimen for the management and control of human gnathostomiasis.

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.

Imported gnathostomiasis manifesting as cutaneous larva migrans and Löffler's syndrome

Here, we report an unusual case of invasive gnathostomiasis in a returning traveller, with a shifting pattern of relapsing cutaneous disease. The previously fit and well 32-year-old man first presented with serpiginous, pruriginous erythematous tracks characteristic of cutaneous larva migrans shortly after returning from South-East Asia. He was systemically well with no other symptoms. After ivermectin therapy, he re-presented with respiratory symptoms, peripheral eosinophilia and transient pulmonary infiltrates; the classic triad of Löffler's syndrome associated with invasive helminth infection. Gnathostoma spinigerum immunoblot was positive. After a second round of ivermectin therapy his respiratory symptoms resolved, but the patient's cutaneous disease relapsed repeatedly over months, with migratory erythematous swellings appearing and settling after a few days. He was treated with a 21-day course of albendazole and is lesion free at 40 weeks post initial presentation.

Ocular Gnathostomiasis-Update of Earlier Survey

Ocular gnathostomiasis is rather a rare food-borne zoonosis caused by infection with the larvae of several species of genus Gnathostoma and is a representative ocular larva migrans syndrome. In our previous literature survey, we found 73 cases of ocular gnathostomiasis reported up to and including 2009, though additional sporadic cases have been reported in Asia and the Americas since that report. Here, we review 10 additional cases reported since 2010, and also update current findings regarding epidemiological and clinical features in affected patients.

Gnathostomiasis: An Emerging Infection of Raw Fish Consumers in Gnathostoma Nematode-Endemic and Nonendemic Countries

BACKGROUND

Gnathostomiasis, a helminthic infection commonly reported in Southeast Asia and Latin America, may follow consumption of raw seafood infected with muscle-encysted larvae of Gnathostoma species nematodes. As a result of increasingly exotic tastes for local ethnic dishes, including raw seafood, some regions outside of gnathostome-endemic areas import live species for raw consumption. This may facilitate imported human gnathostomiasis or potentially the establishment of this zoonosis in formerly nonendemic regions. Traveling to a gnathostome-endemic area is no longer a criterion for diagnosis. The objectives of this review are to enhance clinician awareness of this infection by describing the behavioral risk factors for its acquisition, life-cycle, clinical manifestations, diagnosis, management, and prevention.

METHODS

Internet search engines were queried with the key medical subject heading words. Case reports, case series, epidemiological investigations, and laboratory studies were reviewed; high risk behaviors for gnathostomiasis were identified; and human cases were stratified as cutaneous gnathostomiasis, visceral gnathostomiasis, neurognathostomiasis, and ocular gnathostomiasis.

RESULTS

The greatest risk factors for gnathostomiasis included the consumption of raw freshwater seafood dishes in endemic regions and the consumption of raw imported or domestic seafood dishes in households and ethnic restaurants in many nonendemic regions.

CONCLUSIONS

Gnathostomiasis is no longer a disease of returning travelers, and autochthonous cases may be anticipated to increase as a result of the importation of live Gnathostoma-infected species and the potential establishment of regional zoonoses of Gnathostoma-infected wild species. Since the eradication of gnathostomiasis is unlikely given the global distribution of Gnathostoma nematodes, the only effective preventive strategy is to educate persons in endemic and nonendemic areas that fish, eels, frogs, snakes, and birds must be cooked thoroughly first before eating and not eaten raw or marinated. The onset of migratory subcutaneous swellings with hyper-eosinophilia weeks to months after consuming raw seafood should provoke suspicion of gnathostomiasis.