The importance of collaborative foodborne illness outbreak investigations
While the source of some foodborne illness (FBI) outbreaks are local and can be quickly mitigated, globalized food systems and e-commerce are contributing to much larger and more complex outbreaks that are challenging to investigate. These complexities pose challenges for identifying, investigating, and controlling foodborne illness (FBI) outbreaks, requiring more coordinated interdisciplinary investigations.
This blog delves into the importance of collaborative approaches adopted in Canada for FBI outbreak investigations, the potential of Whole Genome Sequencing (WGS) to permit earlier detection and enhanced clarity of linkages and source attribution in FBI outbreak investigations, and the pivotal role of Environmental Public Health Professionals (EPHP) as well as the current challenges related to FBI outbreak investigations.
Whole Genome Sequencing (WGS) as a tool to enhance FBI outbreak investigations
Advancements in technology, particularly WGS, have transformed the landscape of FBI outbreak investigations. With WGS, genetic relatedness is determined by comparing gene sequences inferring that isolates with more shared sequences are more closely related. Investigators must query if the WGS results make epidemiological sense by considering clustering by time, geographic location, food history, and exposure. WGS offers several advantages over traditional laboratory methods, including earlier detection with less pathogen material and enhanced clarity of linkages and source attribution. Further, WGS provides a single analysis method to sequence entire genomes to identify and characterize pathogens, including typing, antimicrobial resistance (AMR), and virulence profiles, that are rapid and cost-efficient. Lastly, using open databases for sharing real-time pathogenic isolates' global data enhances the identification and investigation of multijurisdictional outbreaks, as demonstrated in the recent cantaloupe investigation.
The role of EPHPs in collaborative FBI outbreak response
In Canada, FBI outbreak investigations require multiple interdisciplinary partners collaborating to identify cases and common exposures, isolate pathogens, contain the outbreak, and communicate information to health partners and the public. The level of collaboration may vary depending on the complexity of the outbreak, ranging from local jurisdiction to international outbreaks. With specialized skills in epidemiology, investigation, environmental health, and risk communication, EPHPs are central to successful FBI outbreak investigations. Their roles include conducting environmental assessments at food facilities, interviewing cases and food handlers, and collaborating with epidemiologists, laboratorians, and other public health professionals to determine the cause of an outbreak and implement control measures. EPHPs provide a unique context and understanding of local communities and food premises impacted by outbreaks. The recent outbreaks involving Escherichia coli in Calgary daycares and Salmonella in cantaloupes highlight the collaborative nature of FBI outbreak investigations and the roles of EPHPs. Both cases required a quick and efficient mobilization of human and other resources to initiate communication, establish a collaborative protocol including knowing “who does what,” and complete the investigation with a clear system for reporting investigation updates. EPHPs applied their expertise to case investigations, environmental assessments, sample collection, risk communication, and control measures implementation in both outbreaks.
FBI outbreak investigation competencies for EPHPs
A recent study identified several FBI outbreak investigation competencies critical for EPHPs, including investigation skills, environmental assessment skills, interview skills, critical thinking, how to implement control measures, and progressive enforcement. Skill development in environmental assessments and interview skills were identified as of paramount importance. Gaining experience can be difficult for emerging EPHPs, due to the infrequency of FBI outbreaks, especially in smaller health authorities. Further, the loss of organizational outbreak experience due to staff turnover, linked to retirements and COVID-19, may have exacerbated the challenges with outbreak response.
Current challenges in FBI outbreak response
Despite using collaborative approaches in FBI outbreak investigations challenges can persist. These challenges include (1) information silos and organizational structures, (2) data collection and standardization, (3) Conflicting lines of evidence, (4) awareness and use of outbreak resources, and (5) sharing outbreak knowledge and experiences.
- Information silos and public health structure
Effective communication and collaboration among public health officials, industry, and other partners is essential for identifying and responding to foodborne outbreaks. Differences in approaches and expectations between health authorities have been identified as a significant coordination challenge, including between different levels of government and neighboring health authorities. Specifically, Information silos within and between health authorities can disrupt communication and coordination during FBI outbreak investigations. Project management principles, including using a responsibility matrix (e.g. RACI Chart), may help ensure strong communication within and between health authorities during FBI outbreak investigations.
- Data collection and standardization
There is currently a lack of standardization in the methods used to identify, investigate, and respond to foodborne outbreaks. The lack of standardization can negatively impact data collection and impede the timely sharing of data, slowing outbreak response and impairing implementation of control measures. Public Health Ontario recently published a technical guidance document, Considerations for Food Safety Investigations at Food Premises during an Outbreak. This document promotes standardized approaches for EPHPs when conducting site visits at food premises during FBI outbreak investigations.
- Merging conflicting lines of evidence
An interesting challenge identified through key informant interviews is the juxtaposition between environmental, epidemiological, and laboratory evidence that can occur in an investigation. Despite having documents like Canada’s Weight of Evidence: Factors to Consider for Appropriate and Timely Action in a FBI Outbreak Investigation, investigators have noted that It can still be challenging to weigh different sources of evidence against each other and determine the level of evidence needed to act.
- Awareness and use of outbreak resources and templates
In a recent study participants noted a lack of awareness about the Public Health Agency of Canada’s Enteric Outbreak Toolkit and other outbreak resources, relying instead on internal agency documents. The reliance on internal documents may result in increased investigations, data collection, and interpretation inconsistencies, resulting in differing approaches to FBI outbreak response.
- Lack of knowledge and experience exchange
Participants in a recent study identified the need to share experiences in outbreak response, especially at the local level. Outbreak summaries can be used to share lessons learned and to generate resources and training for outbreak investigators. These summaries should include details related to tracing information, descriptive epidemiology, hypotheses, and investigation findings, including inspection, environmental assessment, and regulatory actions.
Recent examples of collaboration and challenges in FBI outbreak investigations
Collaboration is the cornerstone of effective FBI outbreak investigations. Establishing protocols for information sharing, conducting joint training exercises, and fostering a unified framework are key elements of successful collaboration. These collaborative approaches ensure a streamlined response across different levels of government, leading to quicker identification and control of outbreaks.
Salmonella outbreak linked to cantaloupes
In the recent cantaloupe outbreak, the Canadian Food Inspection Agency (CFIA) and Public Health Agency of Canada (PHAC) worked closely with US counterparts and provincial health authorities to investigate the outbreak. Epidemiologic, laboratory, and traceback data showed that cantaloupes were contaminated with Salmonella. WGS was used to link cases and help trace the source of the contamination back to its origin. The genetic analysis also showed that illnesses in Canada and the US were caused by the same strain, demonstrating the importance of interagency and international collaboration.
E. coli outbreak linked to daycares in Calgary
The 2023 E. coli outbreak in Calgary, Alberta, highlights some challenges in investigating foodborne outbreaks, including the lack of suspect food samples, an emerging commercial food preparation and distribution trend, and the use of a centralized kitchen serving multiple outlets. Several delays may occur during any outbreak investigation, including notification of initial cases, food and stool sample collection, analysis, and reporting. For example, symptoms of E. coli infections appear within 1 to 10 days after exposure. This delayed reporting and the time needed to complete case interviews often means that food samples from the suspect meal are unavailable when investigators perform their environmental assessment of the suspected food premise.
Conclusion
Success in FBI outbreak investigations in Canada, requires continued collaboration between key partners, including local public health, PHAC, CFIA, laboratory services, international partners, and industry. Learning from past experiences, incorporating innovative technologies like WGS, sharing lessons learned, and fostering a culture of shared responsibility, will enable more efficient and effective foodborne outbreak illness responses across Canada. While challenges persist, continuous improvement and adopting best practices will pave the way for a more resilient and responsive food safety system.
Given EPHPs’ critical role in outbreak investigations, ongoing investment and support for continuous professional development to obtain and enhance competencies and skills, particularly for applications in collaborative FBI outbreak investigations, is required.
The National Collaborating Centre for Environmental Health offers a suite of public health related resources to support professional development, including a series entitled Interdisciplinary foodborne outbreak investigations.
NOTE: The topics discussed in the blog are intended to complement existing outbreak tools and publications, including:
- The Public Health Agency of Canada’s Enteric Outbreak Toolkit.
- Public Health Ontario’s Considerations for Food Safety Investigations at Food Premises during an Outbreak
- The International Association for Food Protection’s Procedures to Investigate FBI guide provides a universal outbreak guide for epidemiological, environmental health assessment, and laboratory investigations.
- Ontario’s Public Health Inspector's (PHI) Guide to Environmental Microbiology Laboratory Testing is an evergreen guide created by Public Health Ontario designed to support effective public health practice
- Canada’s FBI Outbreak Response Protocol (FIORP).
- Canada’s Weight of Evidence: Factors to Consider for Appropriate and Timely Action in a FBI Outbreak Investigation.