FoodNet 2022 Preliminary Data
Documenting the major sources of and trends in foodborne illness provides important information needed to determine whether prevention measures are working. Each year, FoodNet reports on the number of infections in the FoodNet surveillance area from pathogens transmitted commonly through food: Campylobacter, Cyclospora, Listeria, Salmonella, Shiga toxin-producing Escherichia coli (STEC), Shigella, Vibrio, and Yersinia. Laboratory tests, including cultures and culture-independent diagnostic tests (CIDTs), detected these pathogens.
Key Findings from 2022 Surveillance Data
Infections monitored by FoodNet generally returned to or exceeded levels observed in 2016–2018.
Concerted efforts are needed to implement effective prevention strategies.
This year’s report summarizes 2022 preliminary surveillance data. It describes 2022 incidence compared with the average incidence for 2016–2018, the reference period used for the U.S. Department of Health and Human Services (HHS) Healthy People 2030 goals. The report also summarizes cases of hemolytic uremic syndrome (HUS) during 2021.
- In 2022, enteric (intestinal) infections monitored by FoodNet generally returned to or exceeded levels observed in 2016–2018 (before the COVID-19 pandemic).
- Incidence of Campylobacter, Listeria, Salmonella, and Shigella infections did not change in 2022 compared with 2016–2018.
- Incidence of Cyclospora, STEC, Vibrio, and Yersinia infections increased in 2022 compared with 2016–2018.
- Campylobacter and Salmonella remain the top causes of enteric infections monitored by FoodNet.
- Increased use of CIDTs contributed to the increased detection of infections.
- FoodNet data show lack of progress during 2022 toward Healthy People 2030 goals for reducing foodborne illness. Concerted efforts are needed to implement effective prevention strategies to reduce disease burden.
2022 Food Safety Report
Interpreting Changes in Incidences of Infections
Why did the incidences of infections return to levels observed during 2016–2018?
In previous years, factors connected to the COVID-19 pandemic likely influenced the transmission, detection, and reporting of enteric illnesses. These factors included, but were not limited to:
- Interventions to limit the spread of COVID-19, such as
- Restaurant and school closures
- Changes in food preparation practices
- Social distancing
- Decreases in international travel
- Changes in healthcare-seeking behaviors and diagnostic testing practices
As many of these pandemic-related interventions and behavioral changes had ended by 2022, so did their influence on enteric illnesses. A better understanding of how these factors contributed to decreases in foodborne infections during 2020–2021 could help us identify and implement effective prevention strategies.
How has the use of culture-independent diagnostic tests (CIDTs) affected infections tracked by FoodNet?
CIDTs help us rapidly identify treatable infections and detect infections that would have otherwise been missed. This enhanced detection likely contributed to the increased incidence of Cyclospora, STEC, Vibrio, and Yersinia infections.
Though the use of CIDTs helps detect more infections, it can also complicate the interpretation of surveillance data. Distinguishing changes in detection from actual changes in the incidence of infections can be difficult. This is further complicated by the fact that the use of CIDTs has varied by time, pathogen, and clinical diagnostic laboratory.
FoodNet is working on methods to account for the influence of CIDTs on trends in the incidence of infections.
Why did the incidence of some infections increase while others remained stable?
Assessing how various factors affected individual pathogens is always challenging. The increased use of CIDTs likely contributed to the increased detection and incidence of Cyclospora, STEC, Vibrio, and Yersinia infections. This effect may have been larger for these infections because before CIDTs were widely adopted, these pathogens were sometimes overlooked as potential diagnoses. STEC, Vibrio, and Yersinia were the pathogens with the highest proportion of infections detected by CIDT only, and Cyclospora is diagnosed only through culture-independent methods.
Why was 2016–2018 chosen as the reference period?
FoodNet has always set a reference period that can be used for many years. The first reference period was during the first years of FoodNet, 1996–1998. Subsequent reference periods were 10 years (2006–2008) and 20 years (2016–2018) later. The same 2016–2018 reference period used in the current report also matches the reference period used for the U.S. Department of Health & Human Services’ Healthy People goals for Campylobacter, Listeria, Salmonella, and STEC.
How does FoodNet estimate changes in the incidence of infections?
FoodNet uses a Bayesian model to estimate changes in the incidence of infections. The model uses the average annual incidence for 2016–2018 for comparisons. This model adjusts for state-specific trends and changes in population over time. Additional details can be found in “An enhanced method for calculating trends in infections caused by pathogens transmitted commonly through food.”
Questions and Answers About Food Safety
Since 1996, FoodNet has been counting cases and tracking trends for infections transmitted commonly through food. Information gathered on which illnesses are decreasing and which are increasing provides a foundation for food safety policy and prevention efforts. FoodNet’s surveillance data, such as those in this report, show where efforts are needed to reduce foodborne illnesses. Learn more about FoodNet.
CDC uses the best scientific methods and information available to monitor, investigate, control, and prevent foodborne illness. Using epidemiology and laboratory science, CDC assesses public health threats. CDC works closely with state health departments to monitor the frequency of specific diseases and to conduct national surveillance for the diseases it monitors.
When food safety threats appear, CDC collaborates with public health partners, including state health departments, the U.S. Food and Drug Administration (FDA), and the U.S. Department of Agriculture (USDA), to conduct epidemiologic and laboratory investigations to determine the causes of these threats and ways to control them. Although CDC does not regulate the safety of food, CDC works with regulatory agencies to help them develop robust food safety policies and assess the effectiveness of current prevention efforts. CDC provides independent scientific assessment of what the problems are, how they can be controlled, and where the gaps exist in our knowledge. You can find more information on foodborne illness and CDC’s prevention activities on CDC’s Food Safety website.
Government regulation related to food safety is the responsibility of FDA, USDA’s Food Safety and Inspection Service (USDA-FSIS), the National Marine Fisheries Service, and other regulatory agencies. Recent regulatory efforts include the following:
In October 2021, USDA announced it was reevaluating its strategy for controlling Salmonella in poultry, including whether Salmonella should be considered an adulterant in specific raw poultry products.
- Since launching this effort, USDA has focused on gathering information to guide a proposed framework for a new comprehensive strategy to reduce Salmonella illnesses attributable to poultry. USDA has been meeting with stakeholders to hear ideas and asking food safety experts for recommendations.
- In June 2021, USDA-FSIS issued updated guidelines for controlling Salmonella in raw poultry.
- In November 2021, USDA-FSIS presented a new charge to the National Advisory Committee for Microbiological Criteria in Foods to provide guidance on microbiological criteria to reduce foodborne illness from Salmonella in poultry products.
- In August 2022, USDA-FSIS began using quantification for Salmonella in raw poultry rinse samples. Using this new laboratory method, FSIS has taken the first steps to routinely estimating the amount of Salmonella present in a regulatory sample, not solely its presence or absence.
- In 2023, USDA-FSIS released a proposed notice of determination to declare Salmonella an adulterant in not-ready-to-eat breaded and stuffed chicken products. By declaring Salmonella an adulterant in these products, USDA-FSIS will be able to ensure that highly contaminated products that could make people sick are not sold to consumers.
In February 2022, USDA-FSIS proposed performance standards for Salmonella in raw pork products.
FDA is committed to continuous improvement and working to ensure the safety of our food. Some recent activities include:
- The New Era of Smarter Food Safety Blueprint, released in 2020, outlines FDA’s goals over the next decade to leverage new technologies, tools, and approaches to create a safer and more digital, traceable food system. The blueprint focuses on four priority areas, called core elements: enhanced traceability, smarter tools and approaches for prevention and outbreak response, new business models and retail modernization, and food safety culture.
- Also in 2020, FDA released the Coordinated Outbreak Response & Evaluation (CORE) Investigation Table which provides information on FDA foodborne illness outbreak investigations and responses.
- Since 2021, FDA has been collaborating with Stop Foodborne Illness on a series of webinars and white papers on improving food safety culture in the public and private sectors
- In 2021, FDA published a foodborne outbreak response improvement plan to enhance the speed, effectiveness, coordination, and communication of outbreak investigations.
- Since 2022, FDA has been publishing and pursuing prevention strategies to coordinate efforts focused on reducing illnesses from specific foods, including infant formula, enoki and wood ear mushrooms, bulb onions, and queso fresco-type soft cheeses.
- In 2022, FDA published the final rule for additional traceability requirements for certain foods, to enable faster identification and rapid removal of potentially contaminated food from the market.
CDC works closely with regulatory agencies as they, along with industry, develop and implement measures to make our food safer.
Suggested citation: Centers for Disease Control and Prevention (CDC). Preliminary Incidence and Trends of Infections Caused by Pathogens Transmitted Commonly Through Food — Foodborne Diseases Active Surveillance Network, 10 U.S. Sites, 2022. MMWR Morb Mortal Wkly Rep. 2023 June 29.