In 2011, a multidisciplinary team of epidemiologists, physicians, and anthropologists from the Institute of Epidemiology, Disease Control and Research (IEDCR) of the Government of the People’s Republic of Bangladesh (GoB), and the International Centre for Diarrheal Disease Research, Bangladesh (icddr,b) investigated two reported outbreaks of severe diarrhoea affecting urban communities in two districts of Bangladesh (Figure1). The objectives of the outbreak investigations were to identify the etiology, determine the modes of transmission, explore the underlying factors, including environmental and socio-cultural contexts that contributed to these outbreaks, and to suggest control and prevention measures.