Multistate Outbreak of Salmonella Typhimurium Linked to Chicken Salad

The Centers for Disease Control and Prevention (CDC), public health and regulatory officials in several states, and the U.S. Department of Agriculture’s Food Safety and Inspection Service (USDA-FSIS) are investigating a multistate outbreak of Salmonella Typhimurium infections.

Public health investigators are using the PulseNet system to identify illnesses that may be part of this outbreak. PulseNet is the national subtyping network of public health and food regulatory agency laboratories coordinated by CDC. DNA fingerprinting is performed on Salmonella bacteria isolated from ill people by using techniques called pulsed-field gel electrophoresis (PFGE) and whole genome sequencing (WGS). CDC PulseNet manages a national database of these DNA fingerprints to identify possible outbreaks. WGS gives a more detailed DNA fingerprint than PFGE.

As of Feb. 21, 2018, 65 people infected with the outbreak strain of Salmonella Typhimurium have been reported from five states. A list of the states and the number of cases in each can be found on the Case Count Map page. WGS performed on bacterial isolates from ill people showed that they were closely related genetically. This means that people in this outbreak are more likely to share a common source of infection.

Illnesses reported by investigators in Iowa also included ill people who reported eating chicken salad from a Fareway store and who had a diagnostic test showing they were infected with Salmonella bacteria. CDC is not including these people in the outbreak case count until DNA fingerprinting can link their illnesses to the outbreak. Some people may not be included because no bacterial isolates are available for DNA fingerprinting.

Illnesses started on dates ranging from Jan. 8, 2018 to Feb. 10, 2018. Ill people range in age from 11 to 89 years, with a median age of 57. Forty-two people are female. Twenty-eight hospitalizations have been reported. No deaths have been reported.

This outbreak can be illustrated with a chart showing the number of people who became ill each day. This chart is called an epidemic curve, or epi curve. Illnesses that occurred after Feb. 5, 2018, might not yet be reported due to the time it takes between when a person becomes ill and when the illness is reported. This takes an average of 2 to 4 weeks. Please see the Timeline for Reporting Cases of Salmonella Infection for more details.

WGS analysis did not identify predicted antibiotic resistance in 19 isolates from 20 ill people. One isolate contained a gene for resistance to tetracycline, an antibiotic which is not commonly used to treat patients with Salmonella infection. Testing of outbreak isolates using standard antibiotic susceptibility testing methods is currently underway in CDC’s National Antimicrobial Resistance Monitoring System (NARMS) laboratory.

Epidemiologic and laboratory evidence indicates that chicken salad produced by Triple T Specialty Meats, Inc. and sold at Fareway grocery stores is the likely source of this multistate outbreak.

Public health officials in Iowa first detected this outbreak and linked the illnesses to chicken salad sold at Fareway grocery stores. CDC searched the PulseNet database and identified illnesses in other states, and those illnesses have been added to this outbreak. In interviews, ill people answered questions about the foods they ate and other exposures in the week before they became ill. Forty-five (78%) of 58 people interviewed reported eating chicken salad from Fareway stores. Triple T Specialty Meats, Inc. produced the chicken salad that ill people reported eating. Public health officials continue to interview ill people in other states to learn more about what they ate in the week before becoming sick.

On Feb. 9, 2018, Fareway stopped selling chicken salad in all of its stores after the Iowa Department of Inspections and Appeals contacted the company about the illnesses. Iowa Department of Public Health and the Iowa Department of Inspections and Appeals then issued a consumer advisory on Feb. 13, 2018 warning that chicken salad sold at Fareway may be contaminated with Salmonella.

Investigators in Iowa collected chicken salad from two Fareway grocery store locations in Iowa for laboratory testing. The outbreak strain of Salmonella Typhimurium was identified in both samples.

On Feb. 21, 2018, Triple T Specialty Meats, Inc. recalled all chicken salad produced from Jan. 2, 2018 to Feb. 7, 2018. The recalled chicken salad was sold in containers of various weights from the deli at Fareway grocery stores in Iowa, Illinois, Minnesota, Nebraska, and South Dakota from January 4, 2018 to February 9, 2018. CDC recommends that people do not eat recalled chicken salad. Throw it away or return it to the place of purchase.

Source: CDC