FSIS Foodborne Illness 

Outbreak Investigations, 

Fiscal Year 2020

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 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 includes details like the foods ill people ate, where they purchased 

these foods, and where they live. Laboratory information includes comparing bacteria from 

FSIS 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. These actions may include requesting that a 

company remove product from commerce and issuing a press release announcing that a 

Federal establishment is voluntarily recalling product(s) linked to human illnesses or notifying 

the public of potential food safety concerns through the issuance of a public health alert. 

This report summarizes outbreaks that FSIS investigated from October 1, 2019 to September 

30, 2020, Fiscal Year 2020 (FY 2020). While the number of outbreaks FSIS investigates 

annually does fluctuate, it is important to acknowledge how changes to daily life due to the 

COVID-19 pandemic likely affected the number of reported foodborne illness outbreaks in FY 

2020. According to the Centers for Disease Control and Prevention (CDC), in calendar year 

2020 there was a 26% decrease in reported infections of the most common foodborne 

pathogens monitored by FoodNet compared to the previous three years. Several factors likely 

played a part, including healthcare-seeking behaviors, hygiene practices, and where 

consumers ate their meals.
Fiscal Year 2020 in Review

During FY 2020, FSIS investigated 12 outbreaks in coordination with local, State, and Federal 

public health partners. These outbreaks involved approximately 400 illnesses and more than 

150 hospitalizations. State public health partners (6, 50.0%) and the CDC (4, 33.3%) notified 

FSIS about the majority of these outbreaks. Eleven (91.7%) outbreaks involved illnesses in 

more than one state. 

Of the 12 outbreaks investigated by FSIS in FY 2020, Salmonella (6, 50.0%) was the most 

common pathogen followed by STEC (4, 33.3%) and Lm (2, 16.7%) (Figure 1). Beef (5, 41.7%) 

was the most common food product of interest (Figure 2). The six Salmonella outbreaks 

investigated in FY 2020 involved five serotypes: Dublin; Enteritidis; I 4,[5],12:i:-; Thompson;

and Typhimurium. All four STEC outbreaks investigated in FY 2020 were caused by serogroup 

O157:H7.

* Product investigated included multiple ingredients

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

Two (16.7%) outbreaks led to a recall of FSIS-regulated products in FY 2020. FSIS requests that 

establishments recall remaining product from commerce when it is found to be associated 

with an outbreak, there is enough information to identify the product, and the product is still 

in commerce. One additional outbreak led to a recall initiated by a retail store after a State 

public health partner notified them that product further processed and packaged by the retail 

store was associated with an outbreak. Table 1 depicts characteristics about these outbreaks

investigated in FY 2020, including information on the serotype/serogroup, product of interest, 

if FSIS or non-FSIS samples were determined to be genetically related to human illnesses, and 

if the available outbreak information resulted in a recall of FSIS-regulated products from

commerce to prevent additional illnesses.

Salmonella

(6, 50.0%)

STEC 

(4, 33.3%)

Listeria

(2, 16.7%)

Figure 1. FY 2020 Outbreaks by 

Pathogen (N = 12)

Beef

(5, 41.7%)

Chicken (2, 16.7%)

Multiple 

Products+

(2, 16.7%)

Pork

(1, 8.3%)

Non-FSIS regulated 

product (1, 8.3%)

Multi-ingredient product* 

(1, 8.3%)

Figure 2. FY 2020 Outbreaks by 

Product of Interest (N = 12)
Table 1. FY 2020 Outbreak Characteristics 

Pathogen Serotype/Serogroup ProductAFSIS IsolatesD Non-FSIS IsolatesE RecallF

STEC

O157:H7 Beef No Yes NoG

O157:H7 Non-FSIS Regulated 

Product (Romaine) No Yes YesH

O157:H7 Multi-ingredientB No No No

O157:H7 Beef No No No

Lm

Multiple ProductsC Yes No No

Multiple ProductsC No No No

Salmonella

Dublin Beef Yes Yes Yes

Enteritidis Chicken Yes No No

I 4,[5],12:i:- Pork No No No

Thompson Chicken No Yes No

Typhimurium Beef Yes No No

Typhimurium Beef Yes No No

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

B) Product(s) investigated included multiple ingredients

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

D) 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 cluster

E) 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 cluster

F) Based on available evidence, FSIS-regulated product was determined to be the cause of human 

illnesses and an FSIS-regulated establishment voluntarily recalled product from commerce

G) Recall of product processed and packaged by a retail store; retail records did not allow FSIS to 

definitively determine the FSIS-regulated supplying establishment

H) Recall of FSIS-regulated salad containing chicken; romaine lettuce was later determined to be the 

outbreak source

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 has conducted AARs 

for several FY 2020 outbreak investigations to identify best practices and areas for 

improvement. 

FSIS conducted an AAR in collaboration with public health partners for a Salmonella Dublin 

outbreak associated with ground beef. 

• As part of the investigation, investigators used an Electronic Benefit Transfer (EBT) card 

to identify specific products purchased by the case. 

• Using the EBT card records along with retail grinding records, investigators were able to 
identify the FSIS-regulated supplier of ground beef purchased by the case. 

• In situations where documents traditionally used for traceback, such as receipts or 

shopper card records, are not available, other forms of purchase documentation may 

be available to identify products purchased and conduct traceback. 

The AAR conducted for an FY 2020 outbreak of E. coli O157:H7 associated with ground beef 

identified the “intended use” of beef as an important issue. 

• During this outbreak, investigators noted that retailers used whole cuts of beef that had 

been produced by the inspected establishment as intended for intact use, and not 

intended to be ground, to produce raw ground beef. 

• There are minimal safety concerns with intact cuts (e.g., steaks that are not 

mechanically tenderized) externally contaminated with E. coli O157:H7 as normal 

consumer cooking to a rare or medium internal state will eliminate pathogens on the 

exterior. 

• Ground beef and mechanically tenderized steaks, however, are higher-risk products 

because pathogens may move throughout the product and consumer cooking to a rare 

or medium internal state will not eliminate all E. coli O157:H7. 

• Because of this difference, FSIS generally requires that establishments employ more 

rigorous controls to beef that is intended to be ground (or otherwise non-intact), when 

compared to intact beef. 

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.