1. Hôpital Evangélique de Vanga, Vanga Mission, B.P. 4728 Kinshasa 2, Democratic Republic of the Congo
2. Protestant University of Congo, Department of Family Medicine and Primary Care, B.P. 4745, Kinshasa 2, Democratic Republic of the Congo
3. Swiss Tropical and Public Health Institute, Medical Department, 4002 Basel Switzerland
4. University of Basel, 4001 Basel, Switzerland
5. Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Pembroke Place, L3 5QA, UK