[1] Univ N Carolina, Carolina Populat Ctr, Chapel Hill, NC 27515 USA
[2] Univ N Carolina, Dept Maternal & Child Hlth, Chapel Hill, NC USA
[3] Univ N Carolina, MEASURE Evaluat Project, Chapel Hill, NC USA
[4] ICDDR B, Ctr Hlth & Populat Res B, Publ Hlth Sci Div Int Diarrheal Dis Res, Dhaka, Bangladesh