[1] Univ Ibadan, Univ Coll Hosp, Coll Med, Inst Child Hlth, Ibadan 5116, Nigeria
[2] Univ Coll Hosp, Dept Community Med, Ibadan, Oyo, Nigeria
[3] Univ Kansas, Med Ctr, Dept Prevent Med & Publ Hlth, Lawrence, KS 66045 USA
[4] Ibadan North Local Govt Area, Oyo, Oyo State, Nigeria