1. Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, UK and KEMRI-Wellcome Trust, Kilifi 80108, Kenya
2. Institute of Tropical Medicine and International Health, Charité University Medicine, Berlin 10117, Germany
3. Human Health Theme, International Centre of Insect Physiology and Ecology, Nairobi 00100, Kenya
4. Institute of Microbiology and Infectious Diseases Immunology, Charité University Medicine, Berlin, Germany