1. Department of Family Medicine and Primary Care, University of the Witwatersrand , Phillip V Tobias Health Sciences Building, 29 Princess of Wales, Parktown, Johannesburg 2193 , South Africa
2. Department of Family Medicine and Primary Care,Protestant University of Congo, Croisement des Avenues Libération et Triomphale , Commune de Lingwala, Kinshasa , Democratic Republic of the Congo
3. Department of Family Medicine and Primary Care,University of the Witwatersrand , Phillip V Tobias Health Sciences Building, 29 Princess of Wales, Parktown, Johannesburg 2193 , South Africa