Salmonella Infantis Outbreak Linked to

Chicken Products 

Outbreak Investigation After-Action Report, 2018-11

Highlights

• This outbreak was linked to chicken products and

was an industry-wide outbreak of Salmonella

Infantis. 

• Pulsed-field gel electrophoresis (PFGE) was the 

primary method for identifying the outbreak strain in 

chicken products and ill people. 

• No FSIS-regulated establishment was identified as 

the source of the outbreak because there was no

definitive exposure and shopper purchase 

information available for traceback. 

• The Centers for Disease Control and Prevention 

(CDC) issued a media alert and an investigation 

notice in 2018 and an investigation notice in 2019

about this outbreak.

State of residence for Salmonella Infantis cases

Outbreak at a Glance

Illnesses 129

States included 32

Hospitalizations 25

Deaths 1

Response at a Glance

Investigative 

samples tested

0 

Recall or Public 

Health Alert

No

Process improvements

• FSIS improved early 

industry notification of 

outbreaks and novel 

findings process. 

• FSIS routinely posts 

sampling data and will 

continue to inform industry 

early during outbreak 

investigations.

Food Safety and Inspection Service

U.S. DEPARTMENT OF AGRICULTURE
What Happened?

From May 2018 to February 2019, the Centers for Disease Control and Prevention 

(CDC) and the Food Safety and Inspection Service (FSIS) investigated an outbreak of 

129 Salmonella Infantis illnesses, including one death reported from New York, 

associated with raw chicken products. At the time of the outbreak, cases were identified 

using PFGE (pattern JFXX01.1080). This strain was identified in samples taken from 

raw chicken pet food, raw chicken products, and live chickens. The detection of 142 

chicken isolates from 76 establishments suggested that this outbreak was linked to 

multiple producers of chicken products spread throughout the industry. 

The National Antimicrobial Resistance Monitoring System (NARMS) first identified f this 

multi-drug resistant (MDR) Salmonella Infantis strain in retail chicken during routine 

surveillance in 2014. Antibiotic resistance testing conducted by CDC on Salmonella

bacteria isolated from ill people in this outbreak also showed that the outbreak strain 

was resistant to multiple antibiotics. Over 90% of chicken isolates were MDR. Even with

detailed exposure and purchase information, there was not sufficient evidence to make 

the direct link needed to take regulatory action in response to this outbreak. However, 

the CDC issued a media alert and an investigation notice in 2018 to alert the public 

about the outbreak. FSIS and CDC met with the National Chicken Council (NCC) 

October 2019, November 2019, and December 2019 to share information about this 

outbreak investigation. FSIS shared information on trends in identification of the 

pathogen in FSIS establishments to help NCC focus their search for mitigations. The 

CDC issued a final investigation notice on this outbreak on February 21, 2019. FSIS 

closed this outbreak on February 28, 2019. 

Since the closing of the outbreak, CDC PulseNet has classified this Salmonella Infantis 

strain as “persistent”. “Persistent” strains cause illnesses consistently over a long time. 

CDC PulseNet continues to monitor this persistent Salmonella Infantis strain. 

FSIS NARMS also continues to (1) monitor Salmonella Infantis trends in isolates, (2) 

monitor antimicrobial resistance and (3) communicate the findings with industry and 

federal partners. Because whole genome sequencing (WGS) was not fully implemented

at the time, it was not used to identify cases during the outbreak investigation period; 

however, it later helped to confirm that this widespread outbreak strain found in the 

chicken industry was distinct from other Salmonella Infantis strains found in chicken 

samples. Find more information on FSIS’ Salmonella Initiative here. 
What Did We Learn from this Outbreak?

What Can You Do to Prevent or Solve the Next 

Outbreak? 

Sampling

Product and environmental samples collected before the outbreak and 

environmental samples collected during the outbreak investigation 

yielded the outbreak strain. This helped identify the source of the 

outbreak and indicated harborage at the regulated establishment, 

highlighting the value of both routine and investigative sampling.

Surveillance

This outbreak was the first time we identified a strain as “persistent,” and 

we are exploring ways to better track and promptly alert stakeholders of 

persistent pathogen strains for which a specific food vehicle has not been 

identified or are novel in nature.

Sampling

Product and environmental samples collected before the outbreak and 

environmental samples collected during the outbreak investigation 

yielded the outbreak strain. This helped identify the source of the 

outbreak and indicated harborage at the regulated establishment, 

highlighting the value of both routine and investigative sampling.

Collaboration

This outbreak showed the importance of increased and early

communication with industry regarding outbreak surveillance and 

outbreak response.

Industry should continue to

focus on decreasing

Salmonella contamination

across the poultry supply 

chain, including at preharvest. 

Continue to work closely with 

local, state, and federal 

partners to detect and 

investigate outbreaks. Public 

health partners should email 

FoodborneDiseaseReports@

usda.gov to notify FSIS if 

FSIS-regulated products may 

be involved in an outbreak. 

Public Health Partners

If you think you have a 

foodborne illness, see a 

health care provider for 

treatment. Your health care 

provider can test you and if 

the tests show you have a 

reportable foodborne illness, 

your state or local public 

health officials should be 

notified. If you suspect an 

FSIS-regulated meat, poultry 

or egg product made you 

sick, see the Report a 

Problem with Food page for 

information on how to notify 

FSIS.

Industry Consumers
Helpful Links

• CDC Media Alert, October 17, 2018

• CDC Food Safety Investigation Notice, October 17, 2018

• CDC Food Safety Investigation Notice, February 21, 2019. 

• Report a Problem with Food | Food Safety and Inspection Service (usda.gov).

• Find more information about FSIS’ response to foodborne outbreaks on the FSIS 

Outbreak Page.

• USDA Effort to Reduce Salmonella in Poultry