Food Safety and Inspection Service

U.S. DEPARTMENT OF AGRICULTURE

FSIS Foodborne Illness 

Outbreak Investigations, 

Fiscal Year 2021 

Introduction

The United States Department of Agriculture’s Food Safety and Inspection Service (FSIS), 

Office of Public Health Science, Applied Epidemiology Staff, coordinates the FSIS response to 

foodborne illness outbreaks that may involve FSIS-regulated products. This includes outbreaks 

that involve four foodborne pathogens that most frequently affect FSIS-regulated products: 

Salmonella, Shiga toxin-producing Escherichia coli (STEC), Listeria monocytogenes (Lm), and 

Campylobacter. FSIS may investigate illnesses associated with other less common foodborne 

pathogens (e.g., Clostridium botulinum) if they are associated with FSIS-regulated products. 

In coordination with our public health partners (the Centers for Disease Control and 

Prevention (CDC) and state public health and agriculture departments), FSIS collects and 

evaluates epidemiologic, laboratory, and traceback information to determine if there is an 

association between an FSIS-regulated product and human illnesses. Epidemiologic 

information can include details like which foods ill people ate, where they purchased these 

foods, and where they live. Laboratory information can include comparing bacteria from FSIScollected product samples and ill people to see if they are genetically similar or have similar 

characteristics. Traceback activities may include determining the location where the product 

was sold (e.g., grocery store, deli counter, or restaurant) or the source of a product (e.g., the 

federally inspected slaughter or processing facility). Depending on the evidence collected 

during an investigation, FSIS may have enough detailed exposure and product information to 

take one or more actions to prevent additional illnesses. 

This report summarizes outbreaks that FSIS investigated from October 1, 2020 to September 

30, 2021, Fiscal Year 2021 (FY 2021). This report also highlights key after-action reviews that 

were conducted and published in FY 2021. While the number of outbreaks FSIS investigates 

fluctuates annually, the COVID-19 pandemic likely decreased the number of reported 

foodborne illness outbreaks in FY 2021. Several factors likely played a part in this decrease, 

including healthcare-seeking behaviors, hygiene practices, and where consumers ate their 

meals. For the previous three fiscal years, the number of outbreaks investigated by FSIS are as 

follows: 16 in 2018, 16 in 2019, and 12 in 2020. 
Fiscal Year 2021 in Review

During FY 2021, FSIS investigated nine outbreaks in coordination with local, state, and federal 

public health partners. These outbreaks involved approximately 200 illnesses and 60

hospitalizations. CDC notified FSIS about most of these outbreaks. Seven (77.7%) outbreaks 

involved illnesses in more than one state. 

Of the nine outbreaks investigated by FSIS in FY 2021, Salmonella and STEC were each 

implicated in three outbreaks, with Lm implicated in two. The ninth investigation involved a 

suspected case of botulism, but neither the botulinum toxin nor the Clostridium botulinum

microorganism was detected in the suspect product (Figure 1). The Salmonella outbreaks 

involved a total of four serotypes: Hadar, Enteritidis, Typhimurium, and Infantis, with both

Typhimurium and Infantis in one outbreak. STEC outbreaks were caused by serogroups 

O157:H7 and O145. Beef was the most common food product linked to outbreaks in 

FY2021(Figure 2).

* Suspected case of botulism investigated. + Multiple FSIS-regulated products were investigated, and a single suspect food was not identified. 

FSIS may ask an establishment to recall product from commerce to protect public health

when it is found to be associated with an outbreak. A recall is a firm’s removal of distributed 

meat or poultry products from commerce when there is a reason to believe that such 

products are adulterated or misbranded under the provisions of the Federal Meat Inspection 

Act, the Poultry Products Inspection Act, or Egg Products Inspection Act. FSIS may issue a 

Public Health Alert (PHA) when the Agency determines that a meat, poultry, or egg product 

may be associated with human illness and no adulterated product remains in commerce or 

FSIS is unable to determine what specific regulated product is implicated by the illnesses and 

thus adulterated. In FY 2021, outbreak investigations led to three recalls of FSIS-regulated 

products and two PHAs. 

Table 1 depicts characteristics about these outbreaks investigated in FY 2021. 

0

1

2

3

4

Salmonella E. coli Listeria Clostridium

botulinum*

Number of Outbreaks

Pathogen

Figure 1: FY 2021 Outbreaks by Pathogen

(N = 9)

0

1

2

3

4

5

Beef Chicken Multiple

Products+

Turkey Pork

Number of Outbreaks

Commodity

Figure 2: FY 2021 Outbreaks by Product of Interest

(N = 9)
Table 1. FY2021 Outbreak Characteristics

Pathogen Serotype/

Serogroup CommodityA FSIS IsolatesB

Non-FSIS 

IsolatesC RecallD PHAE 

Shiga toxinproducing E. 

coli (STEC)

O157:H7 Beef No No No No

O157:H7 Beef No No No No

O145 Beef No No No No

Listeria 

monocytogenes 

(Lm)

Chicken Yes No Yes No

Multiple 

Products++ No No No No

Salmonella

Hadar Turkey Yes Yes No Yes

Enteritidis Chicken Yes Yes Yes Yes

Typhimurium/

Infantis Pork No No Yes No

Clostridium 

botulinum+ Beef No No No No

A) Product investigated by FSIS as possible, likely, or confirmed cause of illnesses during investigation.

B) Isolates recovered from FSIS testing (product, cecal, or environmental) found to be related by whole genome 

sequencing to clinical isolates and are included in the outbreak.

C) Isolates recovered from non-FSIS testing (product, live animal, or environmental) found to be related by whole 

genome sequencing to clinical isolates and are included in the outbreak. 

D) Based on available evidence, FSIS-regulated product was determined to be the cause of human illnesses and an 

FSIS-regulated establishment recalled product from commerce.

E) Based on available evidence, FSIS-regulated product poses a public health risk; however, the product is no longer 

available for sale in commerce or FSIS is unable to determine which specific product is adulterated or misbranded.

+) Investigation of a suspected case of botulism; however, the ill person tested negative for botulinum toxin.

++) Multiple FSIS-regulated products were investigated, and a single suspect food was not identified. 

Learning from Outbreaks

Assessment of outbreaks associated with FSIS-regulated products is crucial to FSIS’ mission 

to prevent foodborne illness and to protect public health. FSIS routinely conducts afteraction reviews (AAR) at the conclusion of foodborne outbreak investigations to identify 

lessons learned that can help improve response and prevent future illnesses. Applying and 

sharing outbreak lessons learned may lead to improved food safety policies and can 

strengthen collaborative investigations with public health partners. FSIS conducted AARs for 

several FY 2021 outbreak investigations to identify best practices and areas for 

improvement. Below are highlights from AARs that were conducted during FY 2021.

FSIS conducted an AAR for an FY 2021 outbreak of Salmonella Enteritidis associated with raw, 

frozen, breaded, stuffed chicken products. During this outbreak, investigators noted that 
consumers used a variety of cooking methods included on the manufacturer’s cooking 

instructions label (oven) and also methods that were not included on the manufacturer’s label 

(such as air fryers and microwaves). 

• Establishments that produce raw, frozen, breaded, stuffed chicken products are 

encouraged to review FSIS Labeling Policy Guidance Uncooked, Breaded, Boneless 

Poultry Products. 

• FSIS brought concerns about these products to the National Advisory Committee on 

Meat and Poultry Inspection (NACMPI) to request advice on reducing illness. NACMPI 

made recommendations below for agency consideration:

o FSIS review of labels and cooking instructions. 

o FSIS review of establishment food safety programs. 

o FSIS conduct exploratory sampling for Salmonella in producing establishments. 

FSIS conducted an AAR for an FY 2021 outbreak of Listeria monocytogenes associated with 

ready-to-eat chicken. 

• Whole genome sequencing of isolates generated by FSIS routine sampling provided

investigators with key data, highlighting the importance of these analyses to generate 

hypotheses related to possible food sources and inform outbreak investigations. 

• Establishments that produce post-lethality exposed (i.e., products that are exposed to 

the environment after the lethality step such as cooking that destroys bacteria present in 

the raw product is complete) ready-to-eat products are encouraged to review FSIS 

compliance guideline for controlling Lm. 

• Rapid coordination and communication allowed for data sharing between FSIS, CDC, 

state public health partners, and industry, and facilitated the rapid response to this 

outbreak. FSIS was able to obtain exposure information quickly and rapidly collect and 

conduct traceback activities of the product for a complicated outbreak.

To see additional FSIS AAR reports and examples of how FSIS has applied outbreak lessons 

learned toward illness prevention, visit Foodborne Outbreak Investigation Outcomes - 

Response and Prevention. 

Contact and Questions

For more information, contact askFSIS.