1. Department of Biology, College of Natural Science, Chung-Ang University, Seoul 156-756, Korea.
2. Department of Tropical and Endemic Parasitic Diseases, National Institute of Health, Seoul 122-701, Korea.
3. National Veterinary Research and Quarantine Service, Anyang 430-016, Korea.
4. Department of Microbiology, Ajou University School of Medicine, Suwon 442-749, Korea.
5. Department of Molecular Parasitology, Sungkyunkwan University School of Medicine, Suwon 440-746, Korea.