The Basics of Foodborne Illness Outbreak Investigations

When a foodborne illness outbreak is detected, public health and regulatory officials work together to determine what caused the outbreak and then take actions to avert additional illnesses from happening.^1,2 During outbreak investigations, public health and regulatory authorities collect three types of data to determine a common food consumed by ill people: epidemiologic, traceback, and laboratory.

State and local partners, in collaboration with the Centers for Disease Control and Prevention (CDC), identify outbreaks and the foods that may be causing the illnesses through public health surveillance and epidemiologic evidence. State and local partners work with the U.S. Food and Drug Administration (FDA) to conduct traceback investigations and examine the food supply chain to determine the origin of the foods identified by the epidemiologic investigations.³ State and local authorities, in partnership with FDA, may use product and environmental sampling, followed by laboratory analyses, to further confirm the identified food as the outbreak source.

The data analyses and subsequent decision-making require extensive input from all investigation partners. Through a combination of the data gathered during an investigation, a food may be implicated as the source of an outbreak. FDA, CDC, and state and local partners work together to inform the public of outbreaks and provide information on how the public can protect themselves from foodborne illness. Based on investigational data, FDA, for example, may ask a firm to recall the product from the market or, in the case of imported products, may issue an import alert to provide additional information to the field to help stop outbreaks and protect public health.

In a peer-reviewed article in the Journal of Emergency Management, FDA authors presented in detail the organizational structure used to detect, respond, and follow up on foodborne illness outbreaks from the perspective of FDA, and specifically how the Incident Command System (ICS) principles are used.⁴ Here, we look at the benefits of using ICS principles during emergency response coordination activities for foodborne illness outbreaks, with input from members of FDA's Coordinated Outbreak Response and Evaluation (CORE) Network. ICS terminology and definitions can be accessed through resources from the Federal Emergency Management Agency (FEMA), which provides a consistent nationwide template to enable partners to work together to prevent, protect against, respond to, recover from, and mitigate the effects of incidents, regardless of cause, size, location, or complexity.⁵

The Integrated Food Safety System and Outbreak Response Landscape

The collaboration and interactions between federal, state, and local partners during outbreak investigations are directly impacted by federal, state, and local laws, including legal restrictions on sharing certain confidential information, and the unique relationships between federal, state, and local agencies.⁶ Local or state agencies conduct most investigations of foodborne illness outbreaks following their own policies and procedures, and serve as the first responders to incidents that originate within their state.⁷ 

In 2011, the Food Safety Modernization Act (FSMA) mandated the development of strategies to enhance food safety that align with FDA's efforts to create and execute processes toward achieving a national integrated food safety system (IFSS).⁸ An IFSS represents a partnership among federal, state, local, and territorial agencies to achieve the public health goal of a safer food supply.⁸ One example of an integrated approach to food safety in such a situation includes the 24 collaborative Rapid Response Teams (RRTs) across the country that plan, train, and investigate outbreaks using ICS/National Incident Management System (NIMS) principles. These principles guide government responses to incidents that threaten public health and safety.^5,8,9,10 When it comes to multistate outbreak investigations linked to FDA-regulated food products, CDC and FDA collaborate with the states and the RRTs involved.

FDA CORE Organizational Structure

The FDA CORE Network was established in 2011 to coordinate outbreak surveillance, response, and post-response activities related to incidents involving multiple illnesses linked to food and cosmetic products.^2,4 The teams that make up CORE include: Signals and Surveillance Team (SST), multiple CORE Response Teams (CRT), Outbreak Evaluation Team (OET), Outbreak Analytics Team (OAT), and the Communications Team. The teams comprise dedicated staff with multidisciplinary backgrounds, with all members focused on the protection of public health.

CORE is the coordination focal point for all FDA resources during foodborne illness outbreak investigations and provides a platform for partners to share and evaluate information and facilitate decision-making.¹¹ ICS allows for the established organizational structure to be scalable, depending on the magnitude and complexity of the outbreak. As the outbreak complexity increases, the structure may expand from the top down, and responsibilities can be delegated accordingly.⁶ CORE uses ICS principles to respond to both large and small outbreaks, which allows investigative partners to participate in a consistent process with well-established communication channels and clearly stated outcomes.

And So, It Begins: Signals and Surveillance

An outbreak can be broken down to three phases: signals and surveillance, response, and post-response. "At CORE, everything begins with signals," according to Jennifer Beal, the Team Leader for the SST. Signals consist of emerging disease surveillance trends that the SST evaluates in collaboration with CDC, FDA field offices, and state agencies. "My team focuses on early detection that will limit or prevent illness, by continuously evaluating data for signals that an outbreak is potentially linked to an FDA-regulated product," Beal explains.

This early detection also involves weighing a combination of factors to determine whether an outbreak investigation warrants the activation of a CRT for further coordination. Factors considered in this assessment may include: FDA-regulated product identified as a suspect vehicle, pathogen/commodity pairing, vulnerable population impacted, hazard severity, ongoing or growing outbreak, multistate illnesses, pathogen strain commonality and history, product shelf life, required traceback, sampling, company investigations, coordination between multiple internal and/or external partners, public messaging, and international significance.

An outbreak that requires extensive coordination is assigned to a CRT, and an alert notification is shared with partners throughout FDA. This initiates the sequence of meetings that make up the Operational Period Planning Cycle, also known as the Planning P, aimed at the development of an Incident Action Plan (IAP).⁴ According to Jennifer Beal, "Most times, the signals we receive don't develop into outbreaks that require coordination at the federal level, and sometimes incidents may be resolved without even activating a response team." Between CORE's establishment in 2011 and December 2020, approximately 33 percent of incidents evaluated by the SST were transferred to a CRT for further coordination.

CORE's Outbreak Response Operations and Use of ICS

According to Karen Blickenstaff, Response Staff Director of CORE, "Even though CORE does not deploy resources to the field, it is responsible for establishing a national foodborne illness outbreak response strategy for FDA." This charge led to CORE adapting the primary ICS roles as Incident Coordinator, Operations Section Chief, Planning Section Chief, and Communications Specialist. FDA has also adapted the use of ICS forms, and of those, CORE utilizes an IAP that comprises the ICS 201, ICS 202, and a modified ICS 209.

Through incident evaluation, CORE has identified these forms as the most relevant documents in communicating FDA objectives to regulatory partners during outbreak investigations.¹² The ICS 201 is developed by the SST to provide pertinent information to CRTs and includes an epidemiologic map and summary, historical information about the suspect vehicle and pathogen strain, proposed objectives and structure for an incident response, background on preliminary traceback, sampling activities and firms of interest, and a point of contact list. Consequently, ICS 202 is updated for each operational period, and a summary of completed tasks is included in the general situational awareness section of the document.

Following the activation of a CRT, the response coordination is initiated, followed by organizing and analyzing available information, and proposing the length of the operational period. Command and General Staff Meetings are held to review information, set operational objectives, discuss tasks that need to be completed (including laboratory and traceback investigations), allocate resources, and draft ICS documents. "This structure and flow of operations removes the ambiguity and uncertainty that existed prior to adapting ICS to our specific outbreak coordination needs," says Karen Blickenstaff.

The draft ICS 202 containing the proposed objectives for the upcoming operational period is shared with the incident group, which encompasses all outbreak investigation partners, including CDC and relevant state officials, during a CRT-led Tactics Meeting. During this Tactics Meeting, the objectives of the operational period are presented, discussed, and revised as necessary. Investigational information is shared, including epidemiologic, laboratory, and traceback investigation updates, as well as potential communication updates for the public. Partners assist with completion of the overall objectives but develop their own tactics and plans according to their resource availability and limitations.

CORE is responsible for ensuring there is no duplication of efforts. It does this by keeping all stakeholders informed of investigational activities and the big picture. A Planning Meeting is held among CRT members to adjust the objectives based on the information obtained from the Tactics Meeting and the information needed to finalize the ICS 202. Finally, an Operations Briefing email is distributed to the entire incident group, thus initiating the new operational period. "These documents have really helped CORE keep all our partners up to date with the latest information available for each outbreak," says Karen Blickenstaff. "They've kept us organized and focused on accomplishing our objectives for each operational period."

As an incident develops, the same sequence of meetings takes place for each operational period. "Partners know what to expect for each outbreak, and we do our best to deliver on our promise for operational clarity and transparency for each and every outbreak we collaborate with them on," says CORE Director Dr. Stic Harris. CORE has adapted ICS to have operational periods that last days or weeks, depending on the rate at which information is obtained, evidence is developed, illnesses are reported, and public health actions are taken.

Getting the Message Out: Public Communications

The Communications Team members are the Public Information Officers of an outbreak and communicate important information, such as advice for the public, through various media platforms. This team is the focal point for outbreak-related inquiries from, or outreach to, Congress, industry, and media. The Communications Team collaborates with CDC, other federal agencies, and state, local, and international partners to coordinate communication efforts. Between 2011, when CORE was established, and March 2021, the CORE Communications Team issued 104 outbreak advisories and several subsequent updates, resulting in over 400 posts to the FDA.gov website.

According to Corinne Newhart, the Team Leader for the CORE Communications Team, "Issuing public communications aligns with CORE's mission to help control and stop outbreaks by providing the most relevant and actionable information to the public in a timely manner." As part of the process outlined in the draft ICS 202, investigation partners discuss any planned public communications for ongoing outbreaks to help ensure that all public health messaging is strategic, accurate, and effective. Investigation partners also have an opportunity to link to another agency or authority's public communications to help amplify a unified health message when appropriate.

Examples of Outbreak Investigations and Use of ICS

In February 2020, federal, state, and local partners investigated an outbreak of Shiga toxin-producing Escherichia coli O103 infections linked to contaminated clover sprouts.¹³ A total of 51 illnesses were reported from ten states. CORE was engaged in the response of this incident for four months. The response phase included six operational periods ranging from one day at the peak of activities to two weeks toward the end of the incident, completing at least 24 unique objectives. In addition to the members of the CRT, the incident response group included representatives from six different Center for Food Safety and Applied Nutrition (CFSAN) program offices, five Office of Regulatory Affairs (ORA) headquarters offices, eight field offices, one ORA laboratory, CDC, and five different state departments of health or agriculture and their respective laboratories. Federal, state, and local partners conducted epidemiologic and traceback investigations that identified clover sprouts as the source of this outbreak, while the analysis of a clover sprout sample yielded the outbreak strain. This led to a recall of the product in February 2020, as well as FDA issuing a warning letter. CORE Communications issued five web postings to advise the public to discard and avoid eating the recalled clover sprouts.

In March 2020, federal, state and local, and international partners investigated an outbreak of Listeria monocytogenes infections linked to contaminated enoki mushrooms imported to the U.S. from the Republic of Korea.¹⁴ A total of 36 illnesses were reported from 17 states. The response efforts of this incident lasted approximately two months and included seven operational periods ranging from seven days at the peak of activities to two weeks toward the end of the incident. In addition to the members of the CRT, the incident response group included collaboration from five CFSAN program offices, seven ORA headquarters offices, 17 district offices (15 plus two import divisions), two ORA laboratories, CDC, 17 state departments of health and/or agriculture and their associated laboratories, and public health and regulatory authorities from France, Australia, and Canada.

CORE coordinated activities for seven operational periods, establishing more than 18 objectives. Epidemiologic and traceback investigations identified the supply of enoki mushrooms from a single distributor sourced from a single grower in the Republic of Korea, which led to a recall in March 2020. Sample collection and analysis resulted in the recovery of L. monocytogenes isolates from 17 (five FDA, three state, nine foreign) samples and yielded the outbreak strain. CORE Communications issued six web posts to announce updates in the investigation and information about the vehicle linked to illnesses, to link to the firm's recall announcement regarding recalled enoki mushrooms, and to provide actionable advice for consumers who may have purchased the product associated with the L. monocytogenes clinical cases. This was the largest L. monocytogenes outbreak linked to enoki mushrooms that affected multiple countries.

These two examples illustrate the complications and intricacies of responding to foodborne illness outbreaks from a resource management and communications flow standpoint. They also showcase the benefits of adopting ICS principles. "ICS affords us the ability to coordinate across multiple jurisdictions, maintain rapid information flow, ensure accurate data transmission, communicate key findings, and develop reliable public messaging," says Alvin Crosby, Supervisory Consumer Safety Officer and a CRT Team Leader. "While these two outbreaks overlapped temporally, the flexibility afforded by CORE's multiple CRTs, as well as the ICS structure, allowed FDA to respond to both outbreaks without resource capacity strain."

What Does ICS do for CORE?

CORE's adaptation of ICS principles has shown that a modular and flexible system for all outbreak response efforts, regardless of etiology, can be employed by any organization.¹⁵ ICS has resulted in many benefits to the operational cycle of outbreak response.⁴ CORE has been able to provide a reliable, consistent, and transparent approach to outbreak investigations. Federal, state, and local partners participate in ICS meetings and receive consistent outcomes at set periods of time.

According to Dr. Michael Bazaco, an epidemiologist with the OAT, "ICS has been instrumental in refining CORE's outbreak coordination capacity, operating as a forum for laboratory, traceback, and epidemiologic evidence sharing, data analysis, and decision-making. This allows partners to determine next steps through consensus, confidently deploy and leverage resources, and take the necessary regulatory and public health actions."

Outbreak response efforts require a flexible approach when dealing with evolving situations, and ICS allows CORE to use a framework that provides consistent but flexible operational functions. CORE can respond to multiple concurrent outbreaks and, if needed, increase its capacity to respond to an expanding number of outbreaks irrespective of magnitude or complexity.

References

1. U.S. Centers for Disease Control and Prevention (CDC). "Investigating Outbreaks." 2016. https://www.cdc.gov/foodsafety/outbreaks/investigating-outbreaks/index.html.
2. U.S. Food and Drug Administration (FDA). "About the CORE Network." 2020. https://www.fda.gov/food/outbreaks-foodborne-illness/about-core-network.
3. Irvin, K., S. Viazis, A. Fields, S. Seelman, K. Blickenstaff, E. Gee, M. Wise, K. Marshall, L. Gieraltowski, and S. Harris. "An Overview of Traceback Investigations and Three Case Studies of Recent Outbreaks of Escherichia coli O157:H7 Infections Linked to Romaine Lettuce." Journal of Food Protection 84, no. 8 (2021): 1340–1356. https://pubmed.ncbi.nlm.nih.gov/33836048/.
4. Seelman, S., S. Viazis, S. P. Merriweather, T. C. Cloyd, M. Aldridge, and K. Irvin. "Integrating the Food and Drug Administration Office of the Coordinated Outbreak Response and Evaluation Network's Foodborne Illness Outbreak Surveillance and Response Activities with Principles of the National Incident Management System." Journal of Emergency Management 19, no. 2 (2021): 131–141. https://doi.org/10.5055/jem.0567.
5. U.S. Federal Emergency Management Agency (FEMA). "National Incident Management System." 2017. https://www.fema.gov/emergency-managers/nims.
6. Council to Improve Foodborne Outbreak Response. "Guidelines for Foodborne Disease Outbreak Response." 2020. https://cifor.us/downloads/clearinghouse/CIFOR-Guidelines-Complete-third-Ed.-FINAL.pdf.
7. CDC. "National Outbreak Reporting System Guidance." 2017. https://www.cdc.gov/nors/downloads/guidance.pdf.
8. FDA. "National Integrated Food Safety System (IFSS) Programs and Initiatives." 2019. https://www.fda.gov/federal-state-local-tribal-and-territorial-officials/national-integrated-food-safety-system-ifss-programs-and-initiatives.
9. Pierquet, Jennifer, Jessica Badour, Ernie Julian, Alida Sorenson, and Brian Sauders. "Creating the Rapid Response Road Map: Collaboration Points the Way Forward." 2015. https://www.foodsafetymagazine.com/magazine-archive1/augustseptember-2015/creating-the-rapid-response-road-map-collaboration-points-the-way-forward/.
10. Pierquet, Jennifer, Jessica Badour, Ernie Julian, Alida Sorenson, and Brian Sauders. "Where the Rubber Meets the Road: RRTs in Action." 2015. https://www.foodsafetymagazine.com/magazine-archive1/octobernovember-2015/where-the-rubber-meets-the-road-rrts-in-action/.
11. Viazis, S., J. K. Beal, C. Monahan, W. A. Lanier, K. R. Kreil, D. C. Melka, W. D. Boden, J. L. Dion, Z. A. Miller, T. A. Nguyen, L. B. Gieraltowski, and D. L. Zink. "Laboratory, Environmental, and Epidemiologic Investigation and Regulatory Enforcement Actions in Response to an Outbreak of Salmonella Bredeney Infections Linked to Peanut Butter." Open Forum Infectious Diseases 2, no. 3 (2015). https://academic.oup.com/ofid/article/2/3/ofv114/2460477.
12. FDA. "FDA Incident Command System (ICS) Forms." 2018. https://www.fda.gov/emergency-preparedness-and-response/national-incident-management-system-implementation/fda-incident-command-system-ics-forms.
13. FDA. "Outbreak Investigation of E. coli O103: Clover Sprouts (February 2020)." 2020. https://www.fda.gov/food/outbreaks-foodborne-illness/outbreak-investigation-e-coli-o103-clover-sprouts-february-2020.
14. FDA. "Outbreak Investigation of Listeria monocytogenes: Enoki Mushrooms (March 2020)." 2020. https://www.fda.gov/food/outbreaks-foodborne-illness/outbreak-investigation-listeria-monocytogenes-enoki-mushrooms-march-2020.
15. Briggs, S. M. "Regional interoperability: making systems connect in complex disasters." The Journal of Trauma and Acute Care Surgery 67: S88-90 (2009). https://journals.lww.com/jtrauma/Abstract/2009/08001/Regional_Interoperability__Making_Systems_Connect.6.aspx.

Sharon Seelman, M.S., M.B.A., is a Biologist in the Coordinated Outbreak Response and Evaluation Network (CORE) at FDA's Center for Food Safety and Applied Nutrition (CFSAN).

Kari Irvin, M.S., is the Deputy Director at FDA CFSAN's CORE Network.

Stelios Viazis, Ph.D., is a member of FDA CFSAN's CORE Network and part of the CORE Outbreak Analytics team.

Julia Mangia, M.P.H., is a Health Communications Specialist at FDA CFSAN's CORE Network.