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

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.

Infection Status of Gnathostoma spinigerum Larvae in Asian Swamp Eels, Monopterus albus, Purchased from Local Markets in Cambodia

Present study was performed to know the infection status of <i>Gnathostoma</i> sp. larvae in swamp eels from Cambodia. We purchased total 30 Asian swamp eels, <i>Monopterus albus</i>, from local markets in Pursat and Takeo Provinces and Phnom Penh on May and November 2017 and May 2018. All collected eels were transferred to our laboratory with ice and each of them was examined by artificial digestion method. A total of 15 larval gnathostomes (1-5 larvae) were detected from 55.6% (5/9) swamp eels in Pursat Province. No larval gnathostomes were found in 21 swamp eels in Takeo Province and Phnom Penh. The advanced third-stage larvae (AdL₃) detected were 2.575-3.825 (3.250) mm in length and 0.375-0.425 (0.386) mm in width. They had the characteristic head bulb (av. 0.104×0.218 mm) with 4 rows of hooklets, long muscular esophagus (1.048 mm), and 2 pairs of cervical sacs (0.615 mm). The number of hooklets in 4 rows on the head bulb was 41, 44, 47, and 50. In scanning electron microscopy, characteristic features were 4 rows of hooklets on the head bulb, cervical papillae, tegumental spines regularly arranged in transverse striations, and anus. The larval gnathostomes were identified as AdL₃ of <i>Gnathostoma spinigerum</i> based on the morphological characters. By the present study, it has been confirmed that <i>G. spinigerum</i> larvae are infected in Asian swamp eels, <i>M. albus</i>, in Pursat Province, Cambodia.

Percutaneous Emergence of Gnathostoma spinigerum Following Praziquantel Treatment

A Bangladeshi patient with prior travel to Saudi Arabia was hospitalized in the United States for a presumptive liver abscess. Praziquantel was administered following a positive Schistosoma antibody test. Ten days later, a subadult worm migrated to the skin surface and was identified morphologically as Gnathostoma spinigerum. This case highlights the challenges of gnathostomiasis diagnosis, raising questions on potential serologic cross-reactivity and the possible role of praziquantel in stimulating outward migration of Gnathostoma larvae/subadults.

Inventory of Parasites in Freshwater and Seawater Fish at the Fish Quarantine Center and Quality Control of Fisheries Products in Surabaya II

One disease that often attacts fish is a group of parasites or parasitic diseases, parasites are not only dangerous because they are related to their activities, but also trigger the emergence of other pathogenic organisms and cause infections. Therefore, it is necessary to take fish quarantine measures to prevent the spread of diseases carried out by fish quarantine centers. This study was conducted to determine the type of parasite that infested fish samples and determine the prevalence and intensity of fish samples. A total of 48 sample fish consisting of freshwater and seawater fish were analyzed in the laboratory of Balai Karantina Ikan, Pengendalian Mutu dan Keamanan Hasil Perikanan Surabaya II during December - January 2019, either directly or directly (ectoparasites and endoparasites). Parasitic identification was carried out visually and microscopically with an approach based on identification books. The types of parasites that we found during the study consisted of Argulus sp, Trichodina sp, Anisakis sp., Gnathostoma spinigerum, and Gnathostoma spinigerum. The highest prevalence in Scomber Scombrus with Anisakis sp. Amounting to 77.8%, mean while, the lowest prevalence and the intensity is found in Thunnus sp. The prevalence and intensity of parasites are influenced by water quality and pollution.