Investigation Details

Posted December 22, 2021

December 22, 2021

CDC, public health and regulatory officials in several states, and the U.S. Food and Drug Administration (FDA) are collecting different types of data to investigate a multistate outbreak of Listeria monocytogenes infections.

Epidemiologic and laboratory data show that Fresh Express packaged salads may be contaminated with Listeria and may be making people sick.

Epidemiologic Data

As of December 21, 10 people infected with the outbreak strain of Listeria monocytogenes have been reported from eight states (see map). Illnesses started on dates ranging from July 26, 2016 through October 19, 2021 (see timeline).

Sick people range in age from 44 to 95 years, with a median age of 80, and 60% are female. All 10 people have been hospitalized. One death has been reported from Pennsylvania.

The true number of sick people in an outbreak is likely higher than the number reported, and the outbreak may not be limited to the states with known illnesses. This is because many people recover without medical care and are not tested for Listeria.

State and local public health officials are interviewing people about the foods they ate in the month before they got sick. Of the five people interviewed, four (80%) reported eating packaged salads of various types. Two ill people specifically reported eating Fresh Express brand salads. Investigators are working to get more information about the brands and types of packaged salads eaten by sick people.

Laboratory Data

Public health investigators are using the PulseNet system to identify illnesses that may be part of this outbreak. CDC PulseNet manages a national database of DNA fingerprints of bacteria that cause foodborne illnesses. DNA fingerprinting is performed on bacteria using a method called whole genome sequencing (WGS).

WGS showed that bacteria from sick people’s samples are closely related genetically. This means that people in this outbreak likely got sick from the same food.

On December 16, 2021, the Michigan Department of Agricultureexternal icon identified the outbreak strain of Listeria in a bag of Fresh Express Sweet Hearts Romaine Lettuce Sweet Butter Lettuce packaged salad collected from a grocery store during routine sampling.

Public Health Actions

On December 20, 2021, Fresh Express recalledexternal icon packaged salads produced at its facility in Streamwood, Illinois, since November 20, 2021. Do not eat, sell, or serve recalled salads. CDC and FDA are working to determine if additional products are contaminated.

Previous Updates

Public Health Actions

On July 3, 2021, Tyson Foods Inc., a Dexter, Missouri establishment, is recallingexternal icon approximately 8,492,832 pounds of ready-to-eat (RTE) chicken products. CDC advises people not to eat, sell, or serve recalled products. See the complete list of recalled productspdf iconexternal icon, including product and date codes, on the USDA-FSIS website.