1. Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University , Bangkok, Thailand
2. Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital , Vientiane, Lao PDR
3. Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford , Oxford, UK