Deadly Listeria outbreak linked to frozen dairy shakes

An outbreak of infections caused by the bacterium Listeria monocytogenes in the U.S. has rattled consumers who enjoy frozen supplemental shakes. So far, cases have spanned 21 states since 2018, with 38 reported infections and 12 lives lost.

Authorities discovered the source in a facility run by Prairie Farms Dairy in Fort Wayne, Indiana. The Food and Drug Administration (FDA) says environmental samples from the plant matched the outbreak strain, prompting a recall of specific frozen shakes that were linked to illness.

Dr. Olga María Bonilla-Luque, a researcher at the University of Córdoba in Spain, has previously examined ways to control contamination in dairy products. Her work highlights how swift detection and proper handling can make a huge difference in preventing harm.

Understanding the Listeria outbreak

Federal officials saw an unusual number of infections reported among people in long-term care facilities and hospitals.

The U.S. Centers for Disease Control and Prevention (CDC) began looking at several clusters and found that many sick individuals had consumed shakes that were produced by Prairie Farms.

Investigators used whole genome sequencing to show that the bacteria collected from patient samples closely matched those found in the Indiana facility. This connection helped confirm the shakes as a common source of infection.

Recalled Prairie Farms frozen milkshakes

Four-ounce frozen shakes with best-by dates ranging from February 21, 2025, through February 21, 2026, were withdrawn from the market on February 22, 2025.

They came in vanilla, chocolate, strawberry, and strawberry banana flavors, and had been distributed mostly to nursing homes under the Lyons ReadyCare and Sysco Imperial labels.

The manufacturer suggests that anyone possessing these items should “quarantine” them. This advice was provided by Lyons Magnus at the time of recall.

Who is at risk of developing listeriosis?

Affected patients are mostly older adults or people who had already suffered from health complications. A fraction of those who fell ill required soft diets due to difficulties chewing or swallowing.

Certain individuals in these groups face a greater likelihood of severe infection if they consume foods tainted with Listeria.

This bacterium can also pose a risk to pregnant women, as it may lead to miscarriage or stillbirth. Beyond that, symptoms such as fever and stomach distress can occur in otherwise healthy people, but they usually recover without lasting effects.

Most cases occurred in care facilities

Investigators note that many of the outbreak cases happened in 2024 and 2025.

Officials have confirmed that the recalled shakes were in use in several long-term care sites where the vast majority of those affected lived.

Public health agencies advise close monitoring for new cases. Some people avoid medical care if symptoms seem mild. That can cause undercounting, since they never test for Listeria. Another complication is the weeks-long gap before any laboratory links can be made.

A look at Listeria prevention

Experts emphasize thorough food safety checks in facilities that cater to vulnerable populations.

Dr. Bonilla-Luque’s dynamic modeling research on goat milk cheeses suggests that even small lapses in temperature control or poor sanitation can enable bacterial growth in dairy products.

Routine cleaning of production lines and timely inspections can help eliminate cross-contamination points. Regulators recommend consistent staff training, hazard analysis, and updated recall plans so that foods flagged as risky are swiftly removed from circulation.

Protecting consumers from Listeria

Once an outbreak is identified, authorities typically issue guidelines for affected institutions. Early detection and recall announcements limit further exposure. Officials also rely on consumer awareness to keep dangerous products out of circulation.

The CDC encourages prompt testing if someone develops persistent fever and other signs of a Listeria infection.

At-risk groups include those with weakened immune systems, older adults, and pregnant women.

Long-term lessons from the Listeria outbreak

This outbreak highlights the importance of collaboration among federal, state, and local health departments. Swift intervention is often the deciding factor in limiting how many people end up hospitalized.

Producers have reinforced their quality checks in recent years to avoid large-scale incidents. Unfortunately, persistent pathogens thrive in hidden corners, so repeated testing at every stage of food production is necessary.

The study is published in Food Control.

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