Contagious acute gastrointestinal infections.

The epidemiology of acute gastrointestinal illness is complex. The relevant infectious agents may spread from person to person or they may be acquired from a common food or environmental source, often water, but also from animal exposure. This article examines direct human-to-human spread of acute gastrointestinal illness, defined as a syndrome of vomiting, diarrhea, or both that begins abruptly in otherwise healthy persons and is most often self-limited.