1SANG Q. TRAN, 2BINH T. DANG, 3ARNE LEVSEN
1,2Institute of Biotechnology & Environment, Nha Trang University
3Institute of Marine Research, Bergen, Norway
Nematodes of the genus Anisakis are common parasites of marine fish with a worldwide distribution. They have a complex life cycles involving organisms at different trophic levels in the marine ecosystem. Anisakiasis is a zoonotic disease that may affect the human digestive tract after consumption of raw or undercooked seafood containing viable Anisakis third larvae stage (L3). The present study aimed to investigate the species diversity, infestation and molecular phylogeny of Anisakis species (Nematoda: Anisakidae) from Vietnamese tuna (Perciformes: Scombridae). Thus, skipjack tuna - Katsuwonus pelamis (n=35), blackfin tuna - Thunnus atlanticus (n=24) and striped bonito - Sarda orientalis (n=26) were collected in November - December 2017 off the Khanh Hoa province, and subsequently examined for nematodes. A total of 6 Anisakis species were identified, including Type I: A. pegreffii, A. berlandi, A. typica and Anisakis sp.; and Type II: A. paggiae and A. physeteris). The highest prevalence (66.67%) and mean intensity (6.3) were for A. pegreffii on T. atlanticus; and A. pegreffii on K. pelamis, S. orientalis, T. atlanticus, respectively. The lowest values were recorded in A. typica (8.57% and 2.3) on tuna species (K. pelamis, S. orientalis, T. atlanticus and K. pelamis, respectively). Spearman and PCA analyses showed the positive correlation between tuna body and Anisakis species abundant. Tree topology based on 18S rRNA sequences supported 2 separate lineages represented to Anisakis Type I and II, with nucleotide differences ranged from 0.4-1.2%.
Keywords - Anisakid, Tuna, Nematode, 18S rRNA, Infection, Phylogeny.