1. Department of Parasitology, Kangwon National University College of Medicine, Chuncheon 200-701, Korea.
2. Institute of Parasitic Diseases, Zhejiang Academy of Medical Sciences, Hangzhou 310013, Zhejiang Province, P.R. China.
3. Department 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.