[1] Johns Hopkins Bloomberg Sch Publ Hlth, Baltimore, MD USA
[2] Univ Vermont, Coll Engn & Math Sci, Burlington, VT 05405 USA
[3] Univ Vermont, Robert Larner MD Coll Med, Burlington, VT 05405 USA
[4] Vermont Oxford Network, 33 Kilburn St, Burlington, VT 05401 USA
[5] JHPIEGO, Baltimore, MD USA
[6] Johns Hopkins Univ, Ctr Humanitarian Hlth, Baltimore, MD USA