1 Department of Pediatrics, Queen Elizabeth Central Hospital, Blantyre, Malawi.
2 Department of Pediatrics, Malawi Liverpool Wellcome Trust Clinical Research Programme, Queen Elizabeth Central Hospital, Blantyre, Malawi.
3 Department of Clinical Infection, Microbiology and Immunology, Institute of Infection, Ecological Sciences, University of Liverpool, Liverpool, United Kingdom.
4 Department of Pediatrics, Tropical Medicine and Pediatric Infectious Diseases, Baylor College of Medicine, Houston, Texas.
5 National School of Tropical Medicine, Baylor College of Medicine, Houston, Texas.