An outbreak of Listeria infections traced to soft cheese continues, with an additional patient confirmed.
As of June 9, there were nine patients in the outbreak traced to Clover Hill Dairy LLC of Mechanicsville, MD. Eight of the patients have required hospitalization and one has died, according to the Food and Drug Administration.
Sick people’s samples were collected on dates ranging from March 6, 2023, to May 9, 2026. Of the 7 people interviewed, 5 reported eating cheese before becoming ill. Two people reported eating requeson made by Clover Hill Dairy.
The dairy recalled some of its requeson cheese. The dairy has since recalled all of its requeson. Also, Nelson & Isa Lacteos LLC of Bayshore, NY, recalled its of requeson cheese, which was produced by Clover Hill Dairy. Nelson & Isa Lacteos LLC repackaged the cheese and it does not have any labeling.
Clover Hill Dairy products are sold directly from their retail market in Maryland, at farmers markets, and through third party distributors, including in New York and Virginia. The sick people live in Maryland, New York and Virginia.
On May 13, the Suffolk County Health Department notified the New York State Department of Agriculture & Markets of two related Listeria monocytogenes illnesses from the same family, who had purchased food from a local retailer in Brentwood, NY. The following day, the New York State Department of Health confirmed that both cases had consumed requeson cheese purchased at that retailer.
Investigators tested five cheese samples collected from the retailer. One sample of requeson that had been repacked by the retailer tested positive for Listeria monocytogenes, and whole genome sequencing (WGS) confirmed the strain of Listeria found in the requeson cheese matches the strain of Listeria causing illnesses in the two New York cases who reported purchasing cheese from this retailer.
On May 27, the New York agriculture department conducted an inspection at the retailer’s cheese distributor, which identified Clover Hill Dairy LLC of Mechanicsville, MD, as the requeson cheese manufacturer. A sample collected from an unopened 18-pound sealed bucket of requeson manufactured by Clover Hill also tested positive for Listeria monocytogenes. Whole genome sequencing analysis is pending.
The Maryland Department of Health has suspended the Clover Hill Dairy LLC’s operating license, issued a Consumer Advisory, and is conducting a follow up evaluation in cooperation with the facility.
About Listeria infections
Food contaminated with Listeria monocytogenes may not look, smell or taste spoiled but can still cause serious and sometimes life-threatening infections. Anyone who has eaten any of the implicated cheese and developed symptoms of Listeria infection should seek medical treatment and tell their doctors about the possible Listeria exposure.
Also, anyone who has eaten any of the implicated cheese should monitor themselves for symptoms during the coming weeks because it can take up to 70 days after exposure to Listeria for symptoms of listeriosis to develop.
Symptoms of Listeria infection can include vomiting, nausea, persistent fever, muscle aches, severe headache, and neck stiffness. Specific laboratory tests are required to diagnose Listeria infections, which can mimic other illnesses.
Pregnant women, the elderly, young children, and people such as cancer patients who have weakened immune systems are particularly at risk of serious illnesses, life-threatening infections, other complications and death. Although infected pregnant women may experience only mild, flu-like symptoms, their infections can lead to premature delivery, infection of the newborn, or even stillbirth.
