Molecular Identification of Anisakis Larvae Extracted by Gastrointestinal Endoscopy from Health Check-up Patients in Korea

Anisakiasis is a zoonotic disease induced by anisakid nematodes, and endoscopic inspection is used for a diagnosis or remedy for it. Anisakis simplex, Anisakis physeteris, and Pseudoterranova decipiens had been reported to be the major species causing human infections, particularly, in Japan. However, in Korea, recent studies strongly suggested that Anisakis pegreffii is the major species of human infections. To support this suggestion, we collected anisakid larvae (n=20) from 20 human patients who were undergone gastrointestinal endoscopy at a health check-up center in Korea, and molecular identification was performed on the larvae using PCR-RFLP analysis and gene sequencing of rDNA ITS regions and mtDNA cox2. In addition, anisakid larvae (n=53) collected from the sea eel (Astroconger myriaster) were also examined for comparison with those extracted from humans. The results showed that all human samples (100%) were identified as A. pegreffii, whereas 90.7% of the samples from the sea eel were A. pegreffii with the remaining 9.3% being Hysterothylacium aduncum. Our study confirmed that A. pegreffii is the predominant species causing human anisakiasis in Korea, and this seems to be due to the predominance of this larval type in the fish (sea eels) popularly consumed by the Korean people. The possibility of human infection with H. aduncum in Korea is also suggested.

Anisakid Larvae from Anchovies in the South Coast of Korea

Anisakiasis (anisakidosis) refers to a foodborne zoonosis caused by ingesting raw or undercooked marine fish or cephalopods infected with anisakid larvae. The present study was performed to investigate the prevalence of anisakid larvae in anchovies (Engraulis japonica) purchased from 2 local markets in Gyeongsangnam-do, the Republic of Korea (=Korea), during 2018–2019. Anchovies were transported to our laboratory and examined by pepsin-HCl artificial digestion technique followed by microscopic observations and molecular analyses. The overall prevalence of anisakid larvae was 19.5% (39/200), from which a total of 51 larvae (av. 1.3 larvae/infected anchovy) were recovered. Sequencing of the larvae targeting the ITS region, including ITS1, 5.8S rRNA, and ITS2 genes confirmed the species of larvae as Anisakis pegreffii (54.9%; 28/51), Hysterothylacium sinense (23.5%; 12/51), and Hysterothylacium aduncum (21.5%; 11/51). The results suggested that anchovies could be a potential source of human anisakiasis in Korea.

Investigation on the Nematode of Hysterothylacium aduncum (Anisakidae) from Bohai Sea and Yellow Sea in China / 中国寄生虫学与寄生虫病杂志

Objective To investigate Hysterothylacium aduncum (Anisakidae) infection in marine fishes from Bohai Sea and Yellow Sea. Methods Nematodes were collected from the digestive tract of fishes, fixed with hot 4% formalin and preserved in 70% ethanol for study. The specimens were cleared in lactophenol for light microscopical examination, and properly treated for scanning electron microscopy (SEM). Results Among the fishes examined, 14 out of 93 species (15.1%) were found infected by H.aduncum, with a higher prevalence in the fish of Lophius litulon(66.7%), Scomber-omorus niphonius(47.5%), and Gadus macrocephalus(33.3%). H.aduncum infection was first recorded in elasmobranch-Raja smirnovi. Morphological differences of H.aduncum were observed, including the width of lateral alae and the length of intestinal caecum. Conclusion H.aduncum in fishes of Bohai Sea and Yellow Sea in China may be a complex species, and its high prevalence in some fishes reminds the risk of anisakiasis by eating raw fishes.