About the Authors
Department of Biology, Duke University, Durham, North Carolina, United States of America
Imperial College London, Department of Infectious Disease Epidemiology, London, United Kingdom
Fogarty International Center, National Institutes of Health, Bethesda, Maryland, United States of America
The authors have declared that no competing interests exist.
Conceived and designed the experiments: DAR OR KK. Performed the experiments: DAR. Analyzed the data: DAR. Wrote the paper: DAR OR KK.