1 Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400 Thailand; Centre for Global Health and Tropical Medicine, Nuffield Department of Medicine, University of Oxford, Oxford, UK. Electronic address: nickw@tropmedres.ac.
2 Centre for Global Health and Tropical Medicine, Nuffield Department of Medicine, University of Oxford, Oxford, UK; Oxford University Clinical Research Unit, Hospital for Tropical Diseases, Ho Chi Minh City, Vietnam.
3 KEMRI Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya.
4 KEMRI Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya; Institute of Global Health Innovation, Department of Surgery and Cancer, Imperial College London, London, UK.