1. Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, United Kingdom
2. The Peter Medawar Building for Pathogen Research, University of Oxford, South Parks Road, Oxford OX1 3SY, United Kingdom
3. Wellcome Trust-Mahosot Hospital-Oxford University Tropical Medicine Research Collaboration, Microbiology Laboratory, Mahosot Hospital, Vientiane, Laos
4. Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, Churchill Hospital, University of Oxford, Oxford OX3 7LJ, United Kingdom
5. Division of Gastroenterology-Hepatology and Nutrition, University of Utah, Salt Lake City, Utah