[1] Catholic Univ Louvain, Unite Epidemiol Biostat & Methodes Operationnelle, B-1200 Brussels, Belgium
[2] Univ Montpellier I, Transmiss Pathogenese & Prevent Infect VIH, Montpellier, France
[3] Ctr Muraz, Bobo Dioulasso, Burkina Faso
[4] Univ Ouagadougou, Dept Sante Publ, Ouagadougou, Burkina Faso