Editor's Note: This story originally appeared on Trace One.
Each year, an estimated 48 million Americans suffer from foodborne illnesses. While many cases are isolated, others stem from outbreaks — when two or more people become ill from the same contaminated food or drink. These outbreaks are particularly important to track, as they often reveal systemic failures in food production, processing, or handling.
The CDC’s National Outbreak Reporting System (NORS) monitors these events, collecting data on exposure settings, food sources, and the number of people affected. Unlike other CDC initiatives, which track individual foodborne illnesses, NORS focuses specifically on clusters of illness, offering a clearer view of where food safety risks concentrate.
Outbreaks tend to follow seasonal patterns. Bacterial illnesses often spike in summer, while norovirus — the leading cause of outbreaks — peaks during the colder months.
Yet since the start of the COVID-19 pandemic, reported foodborne outbreaks have declined sharply. This trend may reflect temporary changes in behavior, but it also offers lessons for consumers, food preparation workers, and food safety professionals in preventing future illness.
To explore these patterns, researchers at Trace One analyzed the latest NORS data to find the states with the highest rates of foodborne illnesses and how outbreak rates have changed since the pandemic.
Where Do Foodborne Outbreaks Originate?
While foodborne illness can originate anywhere, certain settings are consistently linked to a high number of outbreaks.
Sit-down restaurants accounted for nearly 40% of all reported outbreaks between 2021 and 2023, making them the most common exposure setting by a wide margin. Fast-food establishments contributed another 10%, while caterers and other types of restaurants collectively made up a similar share.
Outbreaks linked to private homes represented 11.4% of cases. Notably, in nearly 17% of outbreaks, the specific setting could not be determined — underscoring the challenges in tracing the origin of many foodborne illnesses.
Outbreaks are also more likely to be associated with certain food categories. Mollusks, including oysters and clams, were associated with 18.3% of outbreaks where a specific food source was identified. These shellfish are often consumed raw and can harbor pathogens like norovirus or Vibrio when harvested from contaminated waters.
Other frequently implicated foods included chicken (13.4%), fish (13.1%), and dairy products (10.6%).
Row crop vegetables (10.4%), such as lettuce and spinach, were also commonly involved in outbreaks. These vegetables are typically consumed raw and can be contaminated during growing, harvesting, or processing. They are also a frequent subject of food recalls, reflecting their broader vulnerability to contamination.
Beef (7.4%) and pork (5.4%) were regularly associated with outbreaks due to E. coli and Salmonella contamination.
Here are the states with the most foodborne disease outbreaks per one million people before and after the pandemic.
10. Hawaii
- Foodborne outbreaks per 1 million (2021–2023): 3.2
- Foodborne outbreaks per 1 million (2017–2019): 7.7
- Outbreak-related illnesses per 1 million (2021–2023): 21.9
- Outbreak-related illnesses per 1 million (2017–2019): 74.8
- Total foodborne disease outbreaks (2021–2023): 14
- Total foodborne disease outbreaks (2017–2019): 33
- Total outbreak-related illnesses (2021–2023): 95
- Total outbreak-related illnesses (2017–2019): 319
- Change in outbreak rate: -58.2%
- Change in illness rate: -70.7%
- Change in outbreaks: -57.6%
- Change in illnesses: -70.2%
9. Washington
- Foodborne outbreaks per 1 million (2021–2023): 3.6
- Foodborne outbreaks per 1 million (2017–2019): 6.0
- Outbreak-related illnesses per 1 million (2021–2023): 37.6
- Outbreak-related illnesses per 1 million (2017–2019): 83.2
- Total foodborne disease outbreaks (2021–2023): 84
- Total foodborne disease outbreaks (2017–2019): 135
- Total outbreak-related illnesses (2021–2023): 880
- Total outbreak-related illnesses (2017–2019): 1,877
- Change in outbreak rate: -40.0%
- Change in illness rate: -54.8%
- Change in outbreaks: -37.8%
- Change in illnesses: -53.1%
8. Idaho
- Foodborne outbreaks per 1 million (2021–2023): 3.6
- Foodborne outbreaks per 1 million (2017–2019): 1.7
- Outbreak-related illnesses per 1 million (2021–2023): 46.4
- Outbreak-related illnesses per 1 million (2017–2019): 9.7
- Total foodborne disease outbreaks (2021–2023): 21
- Total foodborne disease outbreaks (2017–2019): 9
- Total outbreak-related illnesses (2021–2023): 270
- Total outbreak-related illnesses (2017–2019): 51
- Change in outbreak rate: +110.9%
- Change in illness rate: +378.5%
- Change in outbreaks: +133.3%
- Change in illnesses: +429.4%
7. Kansas
- Foodborne outbreaks per 1 million (2021–2023): 3.6
- Foodborne outbreaks per 1 million (2017–2019): 8.5
- Outbreak-related illnesses per 1 million (2021–2023): 30.5
- Outbreak-related illnesses per 1 million (2017–2019): 49.2
- Total foodborne disease outbreaks (2021–2023): 32
- Total foodborne disease outbreaks (2017–2019): 74
- Total outbreak-related illnesses (2021–2023): 269
- Total outbreak-related illnesses (2017–2019): 430
- Change in outbreak rate: -57.2%
- Change in illness rate: -38.1%
- Change in outbreaks: -56.8%
- Change in illnesses: -37.4%
6. Alaska
- Foodborne outbreaks per 1 million (2021–2023): 3.6
- Foodborne outbreaks per 1 million (2017–2019): 5.0
- Outbreak-related illnesses per 1 million (2021–2023): 53.1
- Outbreak-related illnesses per 1 million (2017–2019): 23.5
- Total foodborne disease outbreaks (2021–2023): 8
- Total foodborne disease outbreaks (2017–2019): 11
- Total outbreak-related illnesses (2021–2023): 117
- Total outbreak-related illnesses (2017–2019): 52
- Change in outbreak rate: -27.1%
- Change in illness rate: +125.6%
- Change in outbreaks: -27.3%
- Change in illnesses: +125.0%
5. Colorado
- Foodborne outbreaks per 1 million (2021–2023): 4.2
- Foodborne outbreaks per 1 million (2017–2019): 5.3
- Outbreak-related illnesses per 1 million (2021–2023): 68.0
- Outbreak-related illnesses per 1 million (2017–2019): 79.5
- Total foodborne disease outbreaks (2021–2023): 74
- Total foodborne disease outbreaks (2017–2019): 91
- Total outbreak-related illnesses (2021–2023): 1,194
- Total outbreak-related illnesses (2017–2019): 1,358
- Change in outbreak rate: -21.0%
- Change in illness rate: -14.5%
- Change in outbreaks: -18.7%
- Change in illnesses: -12.1%
4. Utah
- Foodborne outbreaks per 1 million (2021–2023): 4.5
- Foodborne outbreaks per 1 million (2017–2019): 7.1
- Outbreak-related illnesses per 1 million (2021–2023): 52.7
- Outbreak-related illnesses per 1 million (2017–2019): 52.7
- Total foodborne disease outbreaks (2021–2023): 46
- Total foodborne disease outbreaks (2017–2019): 67
- Total outbreak-related illnesses (2021–2023): 536
- Total outbreak-related illnesses (2017–2019): 499
- Change in outbreak rate: -36.1%
- Change in illness rate: -0.1%
- Change in outbreaks: -31.3%
- Change in illnesses: +7.4%
3. Wyoming
- Foodborne outbreaks per 1 million (2021–2023): 5.2
- Foodborne outbreaks per 1 million (2017–2019): 2.3
- Outbreak-related illnesses per 1 million (2021–2023): 72.7
- Outbreak-related illnesses per 1 million (2017–2019): 21.8
- Total foodborne disease outbreaks (2021–2023): 9
- Total foodborne disease outbreaks (2017–2019): 4
- Total outbreak-related illnesses (2021–2023): 127
- Total outbreak-related illnesses (2017–2019): 38
- Change in outbreak rate: +124.0%
- Change in illness rate: +232.8%
- Change in outbreaks: +125.0%
- Change in illnesses: +234.2%
2. Minnesota
- Foodborne outbreaks per 1 million (2021–2023): 5.2
- Foodborne outbreaks per 1 million (2017–2019): 7.3
- Outbreak-related illnesses per 1 million (2021–2023): 53.3
- Outbreak-related illnesses per 1 million (2017–2019): 104.0
- Total foodborne disease outbreaks (2021–2023): 90
- Total foodborne disease outbreaks (2017–2019): 123
- Total outbreak-related illnesses (2021–2023): 917
- Total outbreak-related illnesses (2017–2019): 1,749
- Change in outbreak rate: -28.4%
- Change in illness rate: -48.7%
- Change in outbreaks: -26.8%
- Change in illnesses: -47.6%
1. Rhode Island
- Foodborne outbreaks per 1 million (2021–2023): 5.8
- Foodborne outbreaks per 1 million (2017–2019): 6.9
- Outbreak-related illnesses per 1 million (2021–2023): 37.3
- Outbreak-related illnesses per 1 million (2017–2019): 82.2
- Total foodborne disease outbreaks (2021–2023): 19
- Total foodborne disease outbreaks (2017–2019): 22
- Total outbreak-related illnesses (2021–2023): 123
- Total outbreak-related illnesses (2017–2019): 261
- Change in outbreak rate: -16.9%
- Change in illness rate: -54.7%
- Change in outbreaks: -13.6%
- Change in illnesses: -52.9%
Methodology
This analysis draws on data from the Centers for Disease Control and Prevention (CDC) National Outbreak Reporting System (NORS), which tracks foodborne disease outbreaks across the U.S., including details on outbreak size, exposure setting, and implicated food categories.
The report covers two three-year periods: a pre-COVID baseline (2017–2019) and the latest post-pandemic period with available data (2021–2023). Researchers examined total outbreaks and related illnesses nationally and by state. National figures include multi-state outbreaks, while state-level data reflect only single-state incidents.
To better compare states, annual outbreak and illness rates were calculated per one million residents and averaged over each period. Percentage changes between the two periods were used to assess changes in outbreak frequency and impact.
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