1. Department of Immunology and Medicine, Armed Forces Research Institute of Medical Sciences, 316/6 Rajvithi Road, Bangkok 10400, Thailand
2. Department of Specific Prophylaxis and Tropical Medicine, Medical University of Vienna, Kinderspitalgasse 15, A-1095 Vienna, Austria
3. Angewandte Tropenmedizin und Infektionsepidemiologie, Schiffahrtmedizinisches Institut der Marine, Fachgebiet I 3, Kopperpahler Allee 120, 24119 Kronshagen, Germany