1. Department of Infectious Diseases, Heidelberg University School of Medicine, 69120 Heidelberg, Germany.
2. Parasitology Unit, Max Planck Institute for Infection Biology, 10117 Berlin, Germany.
3. Immunology Unit, Department of Infectious and Tropical Diseases, London School of Tropical Medicine and Hygiene, London WC1E 7HT, UK.
4. Kenya Medical Research Institute–Wellcome Trust Research Programme, Kilifi 80108, Kenya.