Most foodborne outbreaks are local events and will be investigated by city or county health departments. If an outbreak spreads across several cities or counties, a state's health department will get involved in the investigation. When outbreaks involve large numbers of people (or severe or unusual illness), a state may ask for help from the CDC (Centers for Disease Control and Prevention). During widespread outbreaks (linked to food or animal contact) affecting many states at once, the CDC has three main roles: Quickly detecting outbreaks by monitoring nationwide surveillance systems, gathering the evidence to link the outbreak to a likely food or animal source, and communicating with consumers and retailers about the source to prevent additional illnesses.

Sources: Centers for Disease Control and Prevention (CDC), National Center for Emerging and Zoonotic Infectious Diseases (NCEZID), Division of Foodborne, Waterborne, and Environmental Diseases (DFWED)