Of those who became sick, 34 people (89 percent) reported living in long-term care facilities or were hospitalized prior to being sick. Records reviewed from facilities where patients were admitted revealed the shakes were available to residents. Listeria monocytogenes is particularly life-threatening to vulnerable groups who are likely to be residents of long-term care facilities and hospitals, such as the elderly and newborns, and those who are immunocompromised or pregnant.

The outbreak dates back to 2018, with 20 cases occurring in 2024 and 2025, per U.S. Centers for Disease Control and Prevention (CDC) data. In previous investigations of illnesses related to this outbreak, epidemiologic evidence was unable to identify a source; however, recent U.S. Food and Drug Administration (FDA) environmental sampling found the outbreak strain of Listeria monocytogenes.

LyonsReadyCare and Sysco Imperial Frozen Supplemental Shakes (4-ounce) have been voluntarily recalled. According to the recall notifications released by Lyons Magnus and Sysco, the products were produced by Lyons Magnus’ manufacturer Prairie Farms Dairy Inc. in Fort Wayne, Indiana, and were distributed across the U.S. to healthcare facilities, but were not available for retail sale. Lyons Magnus supplied Sysco Imperial and Lyons ReadyCare supplemental shakes linked to the outbreak. Both firms have removed the affected shakes from their distribution stream and inventory, and Lyons Magnus has halted purchases from the affected Prairie Farms facility. A full list of recalled products with “Best By” dates can be found here.

As part of the outbreak investigation, FDA conducted an onsite inspection and collected environmental and product samples at Prairie Farms' Fort Wayne facility, and found three of environmental swabs collected from the processing area to be positive for L. monocytogenes. Whole genome sequencing (WGS) analysis determined that the L. monocytogenes strain detected in the samples is closely related to the outbreak strain. The investigation by FDA, CDC, and state and local partners is ongoing.

More information about the outbreak can be accessed via FDA’s website. There has not yet been any communication about the outbreak directly from CDC, as the agency has not resumed notifications to the public since a communications freeze that was ordered by the presidential administration went into effect on January 21, 2025.

Update, February 25, 2025: Yesterday, CDC issued a food safety alert about the ongoing listeriosis outbreak. According to the alert, CDC previously investigated the 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. After FDA traceback activities identified shakes produced by Prairie Farms to be a food of interest, the outbreak strain was found in environmental samples collected by FDA from Prairie Farms' manufacturing environment on February 4.

WGS data stored in CDC's PulseNet system showed that L. monocytogenes isolated from clinical patients were closely genetically related to the strains isolated from the environmental samples.

Update, May 20, 2025: On May 16, CDC announced that the L. monocytogenes outbreak was over.

A total of 42 people infected with the outbreak strain of L. monocytogenes were reported from 21 states. Illnesses started on dates ranging from August 17, 2018, to March 13, 2025. Of 42 people with information available, 41 were hospitalized. A total of 14 deaths were reported from 10 states: 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 was likely higher than the number reported, and the outbreak may not have been limited to the states with known illnesses," CDC reports. "This is because some people recover without medical care and are not tested for Listeria."