1 Department of Emerging Infectious Diseases, Institute of Tropical Medicine, Nagasaki University, Nagasaki 852-8523, Japan.
2 Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon.
3 Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon; Medical University of Vienna, Vienna, Austria.
4 Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon; Institute of Tropical Medicine, University of Tübingen, and German Centre for Infection Research, Tübingen, Germany.
5 Department of Emerging Infectious Diseases, Institute of Tropical Medicine, Nagasaki University, Nagasaki 852-8523, Japan; National Research Centre for the Control and Prevention of Infectious Diseases, Nagasaki University, Nagasaki 852-8523, Japan. Electronic address: j-yasuda@nagasaki-u.ac.jp.