Listeria Outbreak in Soft Cheese: FDA Investigation and Industry Impact

Listeria Outbreak in Soft Cheese: FDA Investigation and Industry Impact

The FDA and CDC are investigating a multi-state, multi-year Listeria monocytogenes outbreak linked to requeson soft cheese, with eight cases and one death. This article outlines the development, regulatory actions, and implications for pharmaceutical and food safety teams.

Key Takeaways

• FDA and CDC are investigating a multi-state, multi-year Outbreak Investigation of Listeria monocytogenes: Soft Cheese linked to requeson, with eight cases and one death reported; samples collected from March 2023 to May 2026.
• Recalls issued by Sargento Foods (seven cheeses) and Clover Hill Dairy (requeson/soft ricotta).
• FDA advises against eating, selling, or serving recalled products; investigation ongoing.

The Development

On June 5, 2026, the FDA and CDC announced an investigation into a multi-state, multi-year outbreak of Listeria monocytogenes infections potentially linked to requeson, a soft cheese similar to ricotta. According to the FDA's outbreak page, samples from sick individuals were collected between March 6, 2023, and May 9, 2026. Of the seven people interviewed, five reported eating requeson or soft ricotta cheese. The outbreak has sickened eight people across three states and resulted in one death.

Recalls were issued by Sargento Foods Inc., which pulled seven cheeses due to potential Listeria monocytogenes contamination, and by Clover Hill Dairy (Mechanicsville, MD) on June 3, 2026, for requeson/soft ricotta cheese sold from its retail market. The FDA advises consumers not to eat, sell, or serve the recalled products. The investigation remains active, with the agency working alongside state and local partners as well as the CDC.

This is not the first time soft cheese has been tied to a listeriosis outbreak. A previous outbreak in the United States, documented by the FDA, identified five cases across Minnesota, Indiana, Illinois, and Ohio. That investigation also relied on the CDC Listeria Initiative questionnaire, a standardized tool for collecting exposure data from sick individuals. The recurrence of similar contamination patterns underscores the difficulty of eradicating Listeria monocytogenes from dairy production environments, particularly in facilities that handle soft cheeses like requeson.

Implications for Pharma Teams

This outbreak underscores the persistent risk of Listeria monocytogenes in dairy products, which can affect pharmaceutical supply chains that rely on dairy-derived excipients or raw materials. Pharma teams should review supplier contamination histories and consider enhanced testing protocols for raw materials. The investigation employed the CDC Listeria Initiative questionnaire, highlighting the importance of standardized epidemiological tools in outbreak detection. Companies with products targeting immunocompromised populations should monitor FDA updates closely, as listeriosis poses severe risks to these patients. A separate nationwide outbreak of human listeriosis in Switzerland was traced to persisting environmental contamination of a cheese dairy with Listeria monocytogenes, as detailed in a PMC study, serving as a reminder of the need for strong facility sanitation practices.

For pharmaceutical manufacturers that source lactose, milk proteins, or other dairy-derived ingredients, the current outbreak should prompt a closer look at supplier auditing programs. The multi-year duration of this outbreak — spanning from March 2023 to May 2026 — suggests that contamination can persist undetected for long periods, meaning a single negative test result may not guarantee ongoing safety. Companies should also consider whether their raw material testing protocols are sensitive enough to detect low-level Listeria contamination, which can still pose a risk to immunocompromised patients who may use their products.

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