About the Authors

David M Hartley

To whom correspondence should be addressed. E-mail: dhartley@epi.umaryland.edu

Affiliation Department of Epidemiology and Preventive Medicine, University of Maryland School of Medicine, Baltimore, Maryland, United States of America

J. Glenn Morris Jr

Affiliation Department of Epidemiology and Preventive Medicine, University of Maryland School of Medicine, Baltimore, Maryland, United States of America

David L Smith

Affiliation Fogarty International Center, National Institutes of Health, Bethesda, Maryland, United States of America

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

DMH and DLS designed the study and analyzed the data. DMH, JGM, and DLS contributed to writing the paper.