[1] Univ Malawi, Coll Med, Dept Paediat, Lilongwe, Malawi
[2] Univ Malawi, Coll Med, Dept Surg, Lilongwe, Malawi
[3] Univ Michigan, Sch Publ Hlth, Dept Epidemiol, Ann Arbor, MI 48109 USA
[4] Univ Malawi, Coll Med, Malawi Liverpool Wellcome Trust Clin Res Programm, Lilongwe, Malawi
[5] Univ Melbourne, Royal Melbourne Hosp, WH, Dept Med, Parkville, Vic 3050, Australia
[6] Alder Hey Childrens Hosp, Dept Community Paediat, Liverpool L12 2AP, Merseyside, England
[7] Arizona Dept Hlth Serv, Phoenix, AZ 85007 USA