1. Blantyre Malaria Project, Kamuzu University of Health Sciences , Blantyre , Malawi
2. Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Center , Seattle, Washington , USA
3. Department of Statistics, University of Washington , Seattle, Washington , USA
4. Departments of Paediatrics and Child Health, Queen Elizabeth Central Hospital, Kamuzu University of Health Sciences , Blantyre , Malawi
5. The Malawi Liverpool Wellcome Trust Clinical Research Program, Queen Elizabeth Central Hospital, Kamuzu University of Health Sciences , Blantyre , Malawi
6. Department of Microbiology, Kamuzu University of Health Sciences , Blantyre , Malawi
7. Department of Osteopathic Medical Specialties, College of Osteopathic Medicine, Michigan State University , East Lansing, Michigan , USA