In terms of killer diseases, HIV/AIDS, tuberculosis and malaria tend to share the media spotlight as the major public health threats in the world’s low-income countries. Philanthropists and aid agencies follow suit with concern and dollars. But diarrheal diseases like cholera and dysentery — mainly attributable to contaminated water and food — kill and incapacitate more people than any of those other diseases. In fact, diarrheal disease is the third-leading cause of death among adults in the developing world, and the second-leading cause of death among children under five years of age, according to the World Health Organization (WHO).