1. Centre for Neglected Tropical Diseases, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, United Kingdom;
2. DBL-Center for Health Research and Development, Faculty of Life Sciences, University of Copenhagen, 1871 Frederiksberg, Denmark;
3. Department of Entomology and Nematology, University of Florida, Gainesville, Florida 32608;
4. Department of Infectious Disease Epidemiology, Imperial College London, Norfolk Place, London W2 1PG, United Kingdom;