1. Department of Parasitology and Institute of Tropical Medicine, Yonsei University College of Medicine, Seoul 120-752, Korea.
2. Department of Parasitology, Hanyang University College of Medicine, Seoul 133-791, Korea.
3. Department of Parasitology, Seoul National University College of Medicine, and Institute of Endemic Diseases, Seoul National University Medical Research Center, Seoul 110-799, Korea.
4. Department of Parasitology and Medical Research Institute, Chungbuk National University College of Medicine, Chongju, Chungbuk 360-763, Korea.
5. Department of Parasitology and Institute of Health Sciences, Gyeongsang National University College of Medicine, Chinju 660-751, Korea.
6. Department of Parasitology, Korea University College of Medicine, Seoul 136-705, Korea.