1. Department of Parasitology, Seoul National University College of Medicine, and Institute of Endemic Diseases, Seoul National University Medical Research Center, Seoul 110-799, Korea.
2. Department of Parasitology, College of Medicine, Dankook University, Chunan 300-714, Korea.
3. Department of Parasitology, College of Medicine, Gyeongsang National University, Chinju 660-280, Korea.