1. The Department of Biochemistry, Imperial College of Science, Technology and Medicine, London SW7 2AZ,1 and
2. The Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, Oxford University, John Radcliffe Hospital, Oxford,3 United Kingdom, and
3. Wellcome Trust Clinical Research Unit,2 Cho Quan Hospital, and the
4. The Centre for Tropical Diseases4 and
5. University of Medicine and Pharmacy,5 Ho Chi Minh City, and
6. Dong Thap Provincial Hospital, Cao Lanh, Dong Thap,6 Vietnam