Of the 894 outbreaks documenting year of occurrence, 72% occurred between 2000 and 2010. More than 90% of outbreaks occurred in the northern hemisphere and 45% took place during the winter. In general, we found the number of primary cases and persons at risk was significantly lower in outbreaks related to food and waterborne transmission as well as foodservice and healthcare settings. The attack rates were significantly higher in outbreaks related to food, water and those that occurred in the winter. Attack rates were also lower in healthcare-related outbreaks, perhaps on account of proper infection control practices and active surveillance by healthcare facilities to limit the spread of disease.