Research – Multistate Outbreak of Listeria monocytogenes Infections Linked to Fresh, Soft Hispanic-Style Cheese — United States, 2021



What is already known about this topic?

Listeriosis outbreaks are frequently associated with consumption of fresh, soft Hispanic-style cheeses.

What is added by this report?

In early 2021, a multistate outbreak of listeriosis involving 13 cases in four states occurred, resulting in 12 hospitalizations and one death. The outbreak was linked to Hispanic-style cheese within 19 days of cluster detection. Rapid food testing by regulatory agencies in response to the investigation identified the implicated cheese.

What are the implications for public health practice?

To prevent severe health outcomes among persons at increased risk for listeriosis, public health agencies should improve communications, including implementing new methods of dissemination to emphasize the risk from eating fresh, soft Hispanic-style cheeses, even those made with pasteurized milk. 

Listeriosis is a serious infection usually caused by eating food contaminated with the bacterium Listeria monocytogenes. An estimated 1,600 persons become ill with listeriosis each year, among whom approximately 260 die. Persons at higher risk for listeriosis include pregnant persons and their newborns, adults aged ≥65 years, and persons with weakened immune systems. Persons with invasive listeriosis usually report symptoms starting 1–4 weeks after eating food contaminated with L. monocytogenes; however, some persons who become infected have reported symptoms starting as late as 70 days after exposure or as early as the same day of exposure (1). On January 29, 2021, PulseNet, the national molecular subtyping surveillance network coordinated by CDC, identified a multistate cluster of three L. monocytogenes infections: two from Maryland and one from Connecticut (2). CDC, the Food and Drug Administration (FDA), and state and local partners began an investigation on February 1, 2021. A total of 13 outbreak-related cases were eventually identified from four states. All patients reported Hispanic ethnicity; 12 patients were hospitalized, and one died. Rapid food testing and record collection by regulatory agencies enabled investigators to identify a brand of queso fresco made with pasteurized milk as the likely source of the outbreak, leading to an initial product recall on February 19, 2021. Fresh, soft Hispanic-style cheeses made with pasteurized milk are a well-documented source of listeriosis outbreaks. These cheeses can be contaminated with L. monocytogenes unless stringent hygienic controls are implemented, and the processing environment is monitored for contamination (3). U.S. public health agencies should establish or improve communications, including new methods of disseminating information that also effectively reach Hispanic populations, to emphasize the risk from eating fresh, soft Hispanic-style cheeses, even those made with pasteurized milk.

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