Jun-ichi Sanuki
Eiichi Okuzawa
Eiko Imai
Seiki Kobayashi
Tsutomu Takeuchi
Department of Tropical Medicine and Parasitology, School of Medicine, Keio University, Shinjyuku-ku, Tokyo 160, Japan.

Gohta Masuda
Department of Infectious Disease, Tokyo Metropolitan Komagome Hospital, Bunkyo-ku, Tokyo 177, Japan.