Morphologic and Genetic Identification of Diphyllobothrium nihonkaiense in Korea
Hyeong-Kyu Jeon,1Kyu-Heon Kim,2Sun Huh,3Jong-Yil Chai,4Duk-Young Min,5Han-Jong Rim,6
and Keeseon S. Eom1
1Department of Parasitology and Medical Research Institute, Chungbuk BK21 Biomedical Research Center, Chungbuk National University College of Medicine, Cheongju, Chungbuk 361-763, Korea.
2Gyeongin Regional Food and Drug Administration, Incheon 402-835, Korea.
3Department of Parasitology, College of Medicine, Hallym University, Chuncheon 200-702, Korea.
4Department of Parasitology and Tropical Medicine, Seoul National University College of Medicine, and Institute of Endemic Diseases, Seoul National University Medical Research Center, Seoul 110-799, Korea.
5Department of Microbiology and Immunology, School of Medicine, Eulji University, Daejeon 301-746, Korea.
6Department of Parasitology, College of Medicine, Korea University, Seoul 136-705, Korea.
Received April 14, 2009; Revised August 13, 2009; Accepted August 21, 2009.
Abstract
Diphyllobothrium nihonkaiense was first described by Yamane in 1986 but the taxonomical features have been obscure due to lack of critical morphologic criteria in its larval and adult stages. In Korea, this tapeworm had long been known as Diphyllobothrium latum. In this study, we observed 62 specimens collected from Korean residents and analyzed them by morphological features and nucleotide sequences of mitochondrial cox1 gene as well as the ITS1 region. Adult tapeworms were examined after carmine or trichrome stain. Longitudinal sections of the gravid proglottids showed an obtuse angle of about 150 degree between the cirrus sac and seminal vesicle. This angle is known as a major differential point compared with that of D. latum. Nucleotide sequence differences between D. latum and the specimens from Koreans represented 17.3% in mitochondrial DNA cox1 gene. Sequence divergence of ITS1 among 4 Korean isolates was 0.3% and similarity was 99.7% with D. nihonkaiense and D. klebanovskii. All of the Korean specimens analyzed in this study were identified as being D. nihonkaiense (n = 62). We propose its Korean name as "Dong-hae-gin-chon-chung" which means 'long tapeworm of the East Sea' for this newly analyzed diphyllobothriid tapeworm in Korea.
Keywords: Diphyllobothrium nihonkaiense, Diphyllobothrium latum, genetic identification, distribution, Korea.
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