Molecular Identification of Anisakis pegreffii (Nematoda: Anisakidae) in the Sea Eels (Astroconger myriaster) from a Southern Coastal Area of Korea

Abstract

Human anisakiasis is an important fish-borne parasitic zoonosis. It is caused by anisakid larvae that include the species of Anisakis and Pseudoterranova. In Korea, Anisakis type I larvae (mixture of Anisakis simplex and Anisakis pegreffii) were reported from various species of marine fish, including the sea eel and yellow corvina. However, the presence of A. pegreffii has seldom been documented. In this study, Anisakis larvae were collected from the sea eel (Astroconger myriaster) collected from Tongyeong City, a southern coastal area of Korea in March 2013, and molecular analysis was performed. All sea eels examined (20/20, 100%) were found infected with Anisakis larvae. In total, 160 Anisakis type I larvae were recovered from 20 sea eels (average 8 per fish). They were morphologically Anisakis type I larvae, but may be either A. simplex or A. pegreffii. These two species can be differentiated only through molecular analysis of PCR-RFLP and sequencing based on PCR-RFLP patterns using sequences of internal transcribed spacer (ITS1, 5.8 subunit gene and ITS2) of nuclear ribosomal DNA and sequencing analysis of mitochondrial cytochrome c oxidase 2 (cox2). The results showed that 87% of the Anisakis type I larvae (113/129 larvae) were identified as third-stage larvae of A. pegreffii, and 8% (10/129 larvae) were A. simplex larvae. The species of the remaining 5% (6/129) were unknown. This is the first report of A. pegreffii from the sea eels of the south coast in the Republic of Korea.