[1] Johns Hopkins Univ, Sch Hyg & Publ Hlth, Dept Populat & Family Hlth Sci, Baltimore, MD 21218 USA
[2] Johns Hopkins Univ, Sch Hyg & Publ Hlth, Dept Int Hlth, Div Human Nutr, Baltimore, MD 21218 USA
[3] Johns Hopkins Univ, Sch Hyg & Publ Hlth, Dept Int Hlth, Div Community Hlth & Hlth Syst, Baltimore, MD 21218 USA
[4] Univ Montreal, Dept Demog, Montreal, PQ H3C 3J7, Canada
[5] Univ Zimbabwe, Ctr Populat Studies, Harare, Zimbabwe
[6] Univ Zimbabwe, Dept African Languages & Literature, Harare, Zimbabwe