1. Institute for Environmental Sciences, University of Geneva, Bd Carl-Vogt 66, 1205 Geneva, Switzerland
2. Department of Geography, University of Zurich, 8006 Zurich, Switzerland
3. United Nations Office for Project Services (UNOPS), Port Sudan, Sudan
4. Federal Ministry of Health, Khartoum, Sudan
5. The United Nations Population Fund (UNFPA), Khartoum, Sudan
6. The United Nations Population Fund (UNFPA), Technical Division, 605 3rd Ave, New York, NY 10158, USA
7. GeoHealth Group, Institute of Global Health, University of Geneva, 9 Chemin des Mines, 1202 Geneva, Switzerland