A deadly Listeria bacteria found in frozen shakes served at nursing homes and hospitals is behind 12 deaths and 38 illnesses across 21 states, the Food and Drug Administration (FDA) said Monday.

“The FDA and CDC, in collaboration with state and local partners, are investigating illnesses in a multistate outbreak of Listeria monocytogenes infections,” the agency noted on its website.

The Listeria strain, especially dangerous for older adults, was found in the shakes made by Prairie Farms Dairy and marketed under the Lyons ReadyCare and Sysco Imperial brands. The shakes are now under a nationwide recall by the Food and Drug Administration (FDA).

“Distributors and foodservice customers, including hospitals and long-term care facilities who purchased or received recalled Lyons ReadyCare and Sysco Imperial Frozen Supplemental Shakes should not sell or serve these products,” the agency said. “Carefully clean and sanitize any surfaces or containers that they touched and follow FDA’s safe handling and cleaning advice to reduce the risk of cross-contamination.”

It’s noteworthy that Listeria can survive in refrigerated temperatures and can easily spread to other foods and surfaces.

FDA officials became aware of the Listeria outbreak in long-term care facilities (LTCFs) in late November, leading to a deeper investigation, the agency said on Friday.

Between 2024 and 2025, 20 cases linked to the Listeria strain were reported. However, the outbreak itself dates back to 2018, with an FDA investigation recently identifying the bacteria found in infected patients as matching samples from the recalled products, the agency said.

“FDA’s traceback investigation identified that each of the LTCF who supplied invoice information for review from 2024 to present received a frozen supplemental shake of either Lyons ReadyCare or Sysco Imperial brand,” the FDA stated.

Listeria infections can appear the same day or up to 10 weeks after exposure, often before a recall is issued. Symptoms like fever, muscle aches, and confusion can mimic age-related conditions, delaying diagnosis and treatment, especially in long-term care settings, making outbreaks harder to control.

At nursing homes, challenges to containing foodborne illnesses, such as those related to Listeria, include a shortage of staff, delays in implementing food recalls, and misdiagnosis of early symptoms.

The investigation remains open as the source of contamination is unclear at this time, the FDA said. In the meantime, it is advised that all affected shakes be discarded immediately.

Listeria is the third leading cause of death from foodborne illness in the United States, with about 260 deaths annually, according to the Centers for Disease Control and Prevention (CDC).

Sysco is reviewing its supplier safety protocols to prevent future contamination.