1. 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.
2. Department of Parasitology, College of Medicine, Dankook University, Cheonan 330-714, Korea.
3. Department of Parasitology, College of Medicine, Inha University, Incheon 400-712, Korea.
4. Department of Internal Medicine, Seoul National University College of Medicine, Seoul 110-744, Korea.