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CDC’s Role in Outbreak Investigations

Most outbreaks of enteric (gastrointestinal) illnesses are identified and investigated by local and state health departments. These types of outbreaks include foodborne and waterborne outbreaks and those caused by contact with animals (zoonotic outbreaks). CDC provides consultation on some of those investigations, as well as assistance for outbreaks that are particularly large, unusual, or severe.

In recent years, large multistate or nationwide foodborne disease outbreaks have become more commonly recognized. Improved surveillance systems in the United States are better at identifying outbreaks that would previously have been missed. Changing patterns in global food production have resulted in food being distributed over large distances. This change, combined with increasing integration and consolidation of agriculture and food production, can result in a contaminated food rapidly causing a geographically widespread outbreak.

CDC works with a number of public health partners, including:

During a multi-state foodborne disease outbreak, CDC serves as lead coordinator between public health partners to detect the outbreak, define its size and extent, and to identify the source.

Disease Surveillance

CDC maintains and monitors several disease surveillance and outbreak detection systems in collaboration with public health partners.

PulseNet, a sophisticated outbreak detection system, is a national surveillance network of CDC, state, and local public health laboratories and federal food regulatory agency laboratories. PulseNet performs pulsed-field gel electrophoresis (“DNA fingerprinting”) on disease-causing bacteria that may be foodborne to find clusters of ill persons that might be related.

Outbreak Response Team

Once a potential multistate outbreak has been detected, CDC’s Outbreak Response Team engages to investigate it. The Outbreak Response Team collaborates with the national network of epidemiologists and other public health officials who investigate outbreaks of foodborne, waterborne, and other enteric illnesses in the United States.

The Outbreak Response Team works to ensure rapid, coordinated detection and response to multistate outbreaks of enteric diseases and promote comprehensive outbreak surveillance. It also seeks to improve the collaboration and partnership among officials in local, state, and federal agencies who work with foodborne and diarrheal disease outbreak surveillance and response.


CDC also provides assistance when state health departments request it. CDC’s laboratories maintain PulseNet surveillance to identify new cases, conduct advanced laboratory tests of disease-causing microbes, test suspect foods, and provide technical support to public health partners as part of the investigation.

Informing and Protecting the Public

Once a contaminated food source has been identified, public health action to control the outbreak can be taken by regulatory agencies such as FDA and USDA-FSIS. At this stage, CDC continues to investigate other potential sources of illness and monitors for additional illnesses to determine when the outbreak is over.

CDC informs the public about what they can do to protect themselves, advises the medical community about how to treat the infections, and works closely with the regulatory agencies and industry to learn how to prevent similar outbreaks in the future.