1. Wellcome Trust Centre for the Epidemiology of Infectious Disease, Department of Zoology, University of Oxford, Oxford, OX1 3FY, UK.
2. Papua New Guinea Institute of Medical Research, Post Office Box 378, Madang, Papua New Guinea.
3. Department of Medicine, Division of Infectious Diseases, Emory University School of Medicine, Emory Vaccine Center at Yerkes, Atlanta, GA 30329, USA.
4. Biology and Diagnostic Branch, Division of Parasitic Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30341, USA.
5. Institute of Cell, Animal and Population Biology, University of Edinburgh, Edinburgh, EH9 3JN, UK.