[1] Univ Witwatersrand, Fac Hlth Sci, Sch Publ Hlth, MRC Wits Rural Publ Hlth & Hlth Transit Res Unit, Johannesburg, South Africa
[2] Univ Aberdeen, Sch Med Med Sci & Nutr, Inst Appl Hlth Sci, Aberdeen, Scotland
[3] Univ Aberdeen, Sch Educ, Tentre Global Dev, Aberdeen, Scotland
[4] Umea Univ, Dept Epidemiol & Global Hlth, Umea, Sweden
[5] Mpumalanga Prov Govt, Dept Hlth, Mbombela, South Africa
[6] Queen Margaret Univ Edinburgh, Inst Global Hlth & Dev, Musselburgh, Scotland