1. Wellcome Trust Clinical Research Unit1 and
2. Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, John Radcliffe Hospital, Headington, Oxford OX3 9DU, United Kingdom2; and
3. Centre for Tropical Diseases,3 Cho Quan Hospital, Ho Chi Minh City, Vietnam;
4. Department of Virology, U.S. Army Medical Component, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand4;
5. Institute of Health and Community Medicine, Universiti Malaysia Sarawak, Malaysia5