Investigation and molecular identification of Anisakis infection in marine fish sold in Fuxin, Liaoning Province / 中国热带医学

ABSTRACT

@#Abstract Objective　To investigate the infection of Anisakis in marine fish sold in Fuxin, and conduct molecular identification and evolutionary tracing of third-stage larvae to determine Anisakis species. Methods　From 2018 to 2021, marine fish sold in the market were collected randomly, and the third stage larvae of Anisakis were detected in marine fish sold in the market by direct dissection, and the morphological characteristics were used to preliminarily identify species by microscopy; the total DNA was extracted, the internal transcribed spacer sequence of the ribosomal DNA of Anisakis was amplified, and the sequence alignment and evolution analysis were carried out. Results　A total of 289 market-sold sea fish samples of marine fish sold in the market were dissected and 84 samples of Anisakis were detected with a detection rate of 29.1%, of which the infection rates of hairtail and small yellow croaker were higher, at 41.4% and 41.2%, respectively. BLAST comparison of 28 sequences revealed eight species of anisakids, including Anisakis pegreffii, Anisakis simplex, Anisakis typical, Raphidascaris trichiurid, Contracaecum muraenesoxi, Hysterothylcaium zhoushanensis, Hysterothylacium amoyense and Hysterothylcaium fabri,belonging to the genera Anisakis and Hysterothylacium. The phylogenetic tree constructed from 28 sequences generally formed two topological branches, with Anisakis pegreffii, Anisakis simplex, and Anisakis typical forming three separate clusters as the topology branch of Anisakis genus. However, meanwhile, Hysterothylacium, Contracaecum, and Raphidascaris formed a separate topological branch. Conclusions　The marine fish sold in Fuxin City have severe anisakid infection, with a wide variety of anisakid species, the dominant species being Anisakis pegreffii.