[1] Univ Oslo, Inst Hlth & Soc, Postboks 1130 Blindern, N-0318 Oslo, Norway
[2] Med Sans Frontieres Southern African Med Unit, Marshalltown, South Africa
[3] Univ Ioannina, Dept Hyg & Epidemiol, Clin & Mol Epidemiol Unit, Sch Med, Ioannina, Greece
[4] Med Sans Frontieres Operat Ctr Brussels, Operat Res Unit LuxOR, Brussels, Belgium
[5] Minist Sante, Bangui, South Africa
[6] Univ Roma Tor Vergata, Dept Biol, Rome, Italy