1. Division of Infectious Diseases, Department of Medicine, Stanford University, Stanford, CA 94305, USA
2. Department of Family and Community Medicine, University of California San Francisco, San Francisco, CA 94011, USA
3. Careen Center for Health, Gaborone, Botswana
4. Tufts University School of Medicine, Boston, MA 02111, USA
5. Cambridge Institute of Therapeutic Immunology and Infectious Disease (CITIID), Cambridge CB2 0AW, UK
6. Division of Geographic Medicine and Infectious Diseases, Tufts Medical Center, Boston, MA 02111, USA