Hygiene interventions act by reducing contamination of hands, food, and water, and seem to be highly effective: a systematic review of the effect of hand washing with soap has shown that this simple measure is associated with a reduction of 43% in diarrheal disease (Curtis and Cairncross, 2003). However, the effectiveness of such interventions particularly depends on sustained behaviour change (van der Knapp, 2006, Waddington, 2009). Prioritising should therefore be based on local conditions and evidence from implementation rather than from pooled data (WHO, 2008).