1. Department of Internal Medicine, Pusan National University, Yangsan 626-870, Korea.
2. Medical Research Institute, Pusan National University Hospital, Busan 626-813, Korea.
3. Department of Parasitology, School of Medicine, Pusan National University, Yangsan 626-870, Korea.
4. Department of Parasitology, College of Medicine, Kosin University, Busan 602-703, Korea.