1. Malawi–Liverpool–Wellcome Trust Clinical Research Programme, College of Medicine, University of Malawi, Blantyre 3, Malawi;
2. Liverpool School of Tropical Medicine, Pembroke Place, University of Liverpool, Liverpool L3 5QA, United Kingdom;
3. Medical Research Council Centre for Immune Regulation and Clinical Immunology Service, Institute of Biomedical Research, School of Immunity and Infection, College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, United Kingdom;
4. Department of Medicine, College of Medicine, University of Malawi, Blantyre 3, Malawi;
5. Department of Paediatrics, College of Medicine, University of Malawi, Blantyre 3, Malawi;
6. Centre for International Child Health, University of Melbourne Department of Paediatrics and Murdoch Children’s Research Institute, Royal Children’s Hospital, Melbourne, VIC 3052, Australia;
7. Centre of Veterinary Science, University of Cambridge, Cambridge, CB3 0ES, United Kingdom;
8. Division of Medical Microbiology, School of Infection and Host Defence, University of Liverpool, Liverpool L69 3GA, United Kingdom; and
9. Department of Microbiology, College of Medicine, University of Malawi, Blantyre 3, Malawi