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CDC's Role During Investigations of Multistate Outbreaks Linked to Food or Animal Contact

CDC has three main roles during investigations of gastrointestinal illnesses involving multiple states that might be related to food or animal contact:

  1. Quickly detect outbreaks by monitoring nationwide surveillance systems that track diseases.
  2. Gather the evidence linking the outbreak to a likely food or animal source.
  3. Communicate to consumers and retailers about the source of the outbreak to prevent additional illnesses.

CDC coordinates the public health investigation during multistate outbreaks, working closely public health partners, who may include:

Detecting the Outbreak

CDC maintains and monitors several nationwide surveillance systems with its public health partners to track disease and quickly detect outbreaks.

One of CDC's most important disease surveillance systems is PulseNet, the national laboratory network that monitors illnesses caused by bacteria such as Salmonella, E. coli, and Listeria. PulseNet uses DNA fingerprinting of the bacteria making people sick to detect possible outbreaks.

CDC manages PulseNet's database, which keeps track of each bacteria DNA fingerprint collected nationwide since 1996. This allows investigators to quickly connect different fingerprints to each other and determine whether multiple people became sick from bacteria with the same DNA fingerprint. These illnesses are then investigated together to determine if there is a likely source.

Gathering the Evidence

Once public health investigators detect a possible multistate outbreak, CDC coordinates the public health investigation to determine the source of infection. CDC's main goal is to find out what exposure made people sick so they can stop the outbreak and prevent more illnesses. CDC works with federal regulatory partners including FDA and USDA-FSIS on investigations and follow-up actions, such as a food recall or giving advice to animal owners. CDC serves as the public health expert in outbreak investigations, working closely with state and local health officials to gather evidence about exposures, such as to foods or contact with animals, that ill people had in common.

Informing and Protecting the Public

If a food or animal source is identified as the likely source of an outbreak, regulatory agencies, such as FDA and USDA, can take action to control the outbreak. CDC continues to investigate to identify other possible sources of illness, to monitor for additional illnesses, and to confirm that illnesses stop after control measures are taken.

When investigators find the food or animal source of a multistate outbreak, CDC works to inform and protect the public. For outbreaks linked to food, CDC tells the public about the outbreak on the CDC Foodborne Outbreaks website. Outbreaks linked to contact with animals are posted on the CDC Zoonotic Enteric Diseases website. These websites primarily provide information about outbreaks where CDC was leading the response. Information about other outbreaks where CDC was not the lead agency may be found on state or local health departments' individual websites.

Informing the Public
CDC posts a web announcement about the outbreak, how it was identified, and the likely source. This announcement tells people what they can do to protect themselves. CDC shares information about an outbreak so people can learn:

  • Latest investigation details, including the final investigation summary
  • Groups more likely to get sick
  • How many people are sick in each state
  • Advice to consumers and retailers

Protecting the Public
CDC posts web updates during outbreak investigations to provide the most accurate and current information. This allows the public to act and protect themselves from becoming ill. A CDC-released outbreak update provides clear information about who is affected and how to stop the spread of disease.

CDC shares information about outbreaks in several ways:

For more information about how outbreaks are investigated, please see the Multistate and Nationwide Foodborne Outbreak Investigations: A Step-by-Step Guide page.

Illustration of a magnifying glass

Most outbreaks of gastrointestinal illnesses - including those caused by food, water, or animal contact - occur in one state, or in one small part of a state. Local or state health departments identify and investigate those outbreaks. CDC provides consultation on some of those investigations, as well as more hands-on assistance on outbreaks that are particularly large, unusual, or severe.

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