Healthcare-associated outbreaks of gastroenteritis are an increasingly recognized problem, but detailed knowledge of the epidemiology of these events is lacking. We actively monitored three hospital systems in England for outbreaks of gastroenteritis in 2002 to 2003. A total of 2,154 patients (2.21 cases/1,000 hospital-days) and 1,360 healthcare staff (0.47 cases/1,000 hospital-days) were affected in 227 unit outbreaks (1.33 outbreaks/unit-year). Norovirus, detected in 63% of ...