1. Biomedical and Public Health Department, Research Institute of Health Sciences, National Center for Scientific and Technological Research, Ouagadougou P.O. Box 7047, Burkina Faso
2. Ministry of Health and Public Hygiene, Ouagadougou P.O. Box 7009, Burkina Faso
3. Division of Pediatric Surgery, Department of Pediatrics, Gynecology and Obstetrics, University Hospitals of Geneva, University of Geneva, 1205 Geneva, Switzerland