Investigation Update: Listeria Outbreak, Supplement Shakes, February 2025

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, laboratory, and traceback data show that supplement shakes manufactured by Prairie Farms are contaminated with Listeria and are making people sick.

Epidemiologic Data

As of February 21, 2025, 38 people infected with the outbreak strain of Listeria monocytogenes have been reported from 21 states. Sick people's samples were collected on dates ranging from August 17, 2018, to January 23, 2025. Of 38 people with information available, 37 have been hospitalized. Twelve deaths have been reported from California, Illinois, Indiana, Michigan, Minnesota, North Carolina, New York, Tennessee, Texas, and Washington. Most people in this outbreak reported living in long-term care facilities or were hospitalized prior to becoming sick.

The true number of sick people in this outbreak is likely higher than the number reported, and the outbreak may not be limited to the states with known illnesses. This is because some people recover without medical care and are not tested for Listeria. In addition, recent illnesses may not yet be reported as it usually takes 3 to 4 weeks to determine if a sick person is part of an outbreak.

Public health officials collect many different types of information from sick people, including their age, race, ethnicity, other demographics, and the foods they ate in the month before they got sick. This information provides clues to help investigators identify the source of the outbreak.

The table below has information about sick people in this outbreak ("n" is the number of people with information available for each demographic).

CDC investigated this outbreak in 2018, 2021, and 2023. Epidemiologic evidence in previous investigations identified that sick people were residents in long-term care facilities and nursing homes and the likely source was a food served in those types of institutions, but there was not enough information to identify a specific food. CDC reopened the investigation in October 2024 after six new illnesses were reported. In February 2025 after traceback identified a product of interest, the outbreak strain was found in environmental samples from Prairie Farms.

State and local public health officials are interviewing people about the foods they ate in the month before they got sick. Of 38 people with information, 34 (89%) reported living in long-term care facilities or were hospitalized before becoming sick. Eight people reported mechanical soft diets, like supplement shakes. Records reviewed from facilities indicated supplement shakes were available to residents.

Laboratory and Traceback 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 suggests that people in this outbreak got sick from the same food.

FDA traced food records from long-term care facilities. These records showed that supplement shakes made by Prairie Farms were a common food served to people. On February 4, 2025, FDA collected environmental samples at Prairie Farms for testing. On February 19, 2025, WGS showed that the Listeria in the environment are closely related to bacteria from sick people.

Public Health Actions

On February 22, 2025, Lyons Magnus LLC recalled supplement shakes. CDC is advising people not to eat, sell, or serve recalled products.