Occurrence and identification of Anisakis spp. (Nematoda: Anisakidae) isolated from chum salmon (Oncorhynchus keta) in Korea.

The prevalence of infection and the identification of anisakid larvae in chum salmon (Oncorhynchus keta) from the Namdae River, the east coast of Korea, were investigated. In total, 8,358 larvae were collected from 120 fish samples (male = 58 fish, female = 62 fish) in 2008. Fish samples were collected during October and November 2008. All the chum salmon samples (120/120, 100%) caught were infected with anisakid larvae with a high intensity (69.65 ± 48.58 larvae/host). They were mostly found in muscles (98.00%). Based on the morphological and the molecular analysis of PCR-RFLP and sequencing of mitochondrial DNA cox2 gene markers, these nematodes were identified as Anisakis simplex (sensu stricto) third-stage larvae. This is the first report on the molecular identification of anisakid worms from salmonid fishes in Korea. The high occurrence of anisakid worms in chum salmon may pose considerable food safety problems if they were consumed as raw or undercooked, although their commercial value is relatively lower than other salmonid species.