Premise: The cholera epidemic in Zimbabwe appears to have passed its peak, says the World Health Organization (WHO).  The number of new cases recorded in the week to mid-March nearly halved to 2,000, against 3,800 the preceding week and 8,000 cases a week in February.  But the agency warned the weekly statistics were not always accurate.  There have been more than 90,000 cholera cases in Zimbabwe since the start of the epidemic last August, about 4,000 of them fatal.
Hypothesis: Cholera only affected Zimbabwe.