Listeria monocytogenes is a dangerous foodborne pathogen known for its ability to thrive in refrigerated environments and cause serious illness, particularly in vulnerable populations. One of the most severe outbreaks in recent memory was linked to frozen supplemental shakes produced by Prairie Farms and distributed under the Lyons ReadyCare and Sysco Imperial brands. The outbreak spanned over a year and resulted in dozens of hospitalizations and several deaths. Below is a detailed look at the history and timeline of this tragic public health event.
Background: What Is Listeria Monocytogenes?
Listeria monocytogenes is a bacterium responsible for listeriosis, an illness with a relatively low incidence but high hospitalization and mortality rates. Commonly found in soft cheeses, deli meats, and refrigerated ready-to-eat products, Listeria is uniquely dangerous due to its ability to multiply at refrigeration temperatures.
The CDC states that approximately 1,600 people contract listeriosis annually in the U.S., and about 260 die. The bacteria can cause fever, muscle aches, nausea, and in severe cases, meningitis and death. Pregnant women, newborns, older adults, and immunocompromised individuals are especially at risk.
Timeline of the Lyons ReadyCare and Sysco Imperial Listeria Outbreak
Early 2024: Initial Infections
The first cases of Listeria monocytogenes infection began appearing in early 2024. These were sporadic and geographically dispersed, making it difficult to identify a single source.
Late 2024: Case Clusters Identified
As more infections were reported in the fall and winter of 2024, the CDC began noticing genetic similarities among bacterial isolates from affected patients. The illnesses shared the same outbreak strain of Listeria, prompting the CDC and FDA to initiate an investigation.
January 2025: Common Product Link Emerges
By January 2025, investigators had identified a commonality among many of the patients: consumption of frozen supplemental shakes used in healthcare and long-term care facilities. The shakes were sold under the Lyons ReadyCare and Sysco Imperial brands.
These products, manufactured at Prairie Farms Dairy’s Fort Wayne, Indiana facility, were distributed nationwide. Investigators suspected this facility was the contamination source.
February 21, 2025: Voluntary Recall Announced
In response to the growing body of evidence, Lyons Magnus LLC voluntarily recalled the affected 4 oz. frozen supplemental shakes with “best by” dates ranging from 022125 to 022126 (February 21, 2025 to February 21, 2026).
The recall covered multiple flavors and was primarily distributed through healthcare supply chains rather than retail outlets. This heightened the urgency due to the vulnerability of the end consumers, many of whom were elderly or seriously ill.
March–April 2025: Testing and Inspections
Throughout March and April, the FDA conducted environmental sampling at the Fort Wayne facility. Swabs from the production environment tested positive for Listeria monocytogenes matching the outbreak strain. These findings confirmed the facility as the outbreak’s point of origin.
The FDA required Prairie Farms and Lyons Magnus to implement corrective actions including deep sanitation, improved pathogen control protocols, and enhanced monitoring programs.
May 16, 2025: Outbreak Declared Over
On May 16, 2025, the CDC declared the outbreak over, citing that all affected products had been recalled and no additional illnesses had been reported since the recall. At the time of this update, the toll stood at:
- 42 cases across 21 states
- 41 hospitalizations
- 14 deaths
This made the outbreak one of the deadliest listeriosis events in recent U.S. history.
Public Health Response and Lessons Learned
The outbreak triggered renewed calls for stringent food safety protocols, especially in manufacturing facilities supplying healthcare institutions. Lyons Magnus and Prairie Farms worked with regulators to overhaul their sanitation and quality control measures.
The CDC and FDA emphasized several critical lessons:
- Importance of environmental monitoring: Listeria can persist in production facilities and contaminate products over time.
- Need for traceability in institutional foods: Rapid identification of distribution channels is key in outbreak containment.
- Consumer awareness: Although these products were not sold in grocery stores, similar items are available to the public, and understanding food safety risks remains essential.
Final Note
The Listeria outbreak tied to Lyons ReadyCare and Sysco Imperial frozen supplemental shakes serves as a grim reminder of the dangers posed by foodborne pathogens, particularly in products consumed by the most vulnerable populations. Through coordinated federal and state action, the source was identified, the products were removed, and further harm was prevented. But the high number of hospitalizations and deaths underscores the need for continued vigilance, robust inspection systems, and consumer education about the risks of foodborne illness.
