[1] Medecins Sans Frontieres, Dublin, Ireland
[2] Medecins Sans Frontieres, Dept Operat Res, Brussels, Belgium
[3] Minist Hlth & Sanitat, Primary Hlth Care Unit Kailahun, Freetown, Sierra Leone
[4] Medecins Sans Frontieres, Dept Operat Res, Luxembourg, Luxembourg
[5] Dublin City Univ, Sch Math Sci, Dublin 9, Ireland
[6] Publ Hlth Agcy Canada, Natl Microbiol Lab, Special Pathogens Program, Winnipeg, MB, Canada