Facial cleanliness indicators by time of day: results of a cross-sectional trachoma prevalence survey in Senegal oleh Emma M. Harding-Esch, Martin J. Holland, Jean-François Schémann, Mactar Sissoko, Boubacar Sarr, Robert M. R. Butcher, Sandra Molina-Gonzalez, Aura A. Andreasen, David C. W. Mabey, Robin L. Bailey