One person is dead and seven others have been hospitalized after eating soft ricotta and requesón cheese produced by Clover Hill Dairy in Mechanicsville, Maryland. Federal investigators have confirmed eight Listeria monocytogenes cases across Maryland, New York, and Virginia, with the earliest patient specimen collected in March 2023 and the most recent in May 2026. The Maryland Department of Health has suspended the facility’s operating license, and the company has issued a voluntary recall covering products distributed in six states.
Three years of Listeria specimens point to Clover Hill Dairy’s plant
The gap between the earliest and most recent patient specimens, spanning from March 6, 2023, to May 9, 2026, is the single most telling detail in this outbreak. A contamination event tied to one bad batch of milk would typically produce a tight cluster of illnesses over days or weeks. A three-year window, by contrast, suggests a persistent source of Listeria inside the production facility itself, whether in equipment, drains, or environmental niches where the bacterium can survive cleaning cycles and re-enter the food supply.
Maryland health officials appear to have reached a similar conclusion. Rather than simply ordering a product pull, the state suspended Clover Hill Dairy’s license and launched a follow-up evaluation of the facility. License suspensions go beyond recalls; they halt all production until regulators are satisfied the root cause has been identified and corrected. That enforcement step signals the state believes the risk extends beyond any single product lot still on shelves.
How whole-genome sequencing linked patients to recalled cheese
Federal investigators used whole-genome sequencing to match bacterial isolates from patients with isolates recovered from Clover Hill Dairy cheese. The technique compares the full genetic code of Listeria strains, making it possible to connect illnesses that occur years apart if the same strain persists in a facility. According to the federal case summary, eight confirmed infections have been reported so far, all serious enough to require hospitalization.
Of the eight patients, seven were interviewed by public health officials. Five of those seven reported eating soft cheese, and two specifically named Clover Hill Dairy requesón as the product they consumed. While not every patient remembered or reported brand details, the genetic match between clinical isolates and cheese samples provided the critical link tying the illnesses to the Mechanicsville plant.
The U.S. Food and Drug Administration has opened an environmental and traceback investigation, describing the situation as an ongoing Listeria outbreak associated with soft cheeses. FDA officials are working with state partners to review production records, sanitation logs, and distribution data to determine how widely contaminated product may have spread and whether other items produced at the facility could be affected.
Scope of the recall and where products were sold
The voluntary recall covers soft ricotta and requesón cheese distributed between May 4 and May 30, 2026, in Maryland, Washington, D.C., Virginia, New York, New Jersey, and North Carolina. The products were sold in both retail clamshell containers and bulk bucket formats to stores and food service accounts. Lot codes, packaging sizes, and photos are listed in the company’s recall notice, which regulators are urging retailers and consumers to review carefully.
Anyone who purchased soft cheese from Clover Hill Dairy during that window is advised to discard it immediately or return it to the point of purchase. Listeria can grow even under refrigeration, and symptoms may not appear for up to 70 days after exposure, meaning additional cases could still surface. Retailers have been instructed to remove affected products from shelves and to sanitize any surfaces that may have come into contact with the recalled cheese.
Gaps in the investigation and what consumers should watch
Several questions remain open. The FDA has not yet publicly detailed where inside the plant investigators have found Listeria or whether the same outbreak strain has been recovered from drains, equipment, or finished product beyond the recalled lots. It is also unclear whether contamination was limited to soft ricotta and requesón or if other cheeses made on shared lines will require additional testing or recalls.
Regulators have not announced any enforcement actions beyond Maryland’s license suspension, such as warning letters or consent decrees, which are sometimes used to formalize corrective action plans at food facilities with persistent contamination. Those steps may depend on what environmental sampling uncovers and whether Clover Hill Dairy can demonstrate sustained control of Listeria in follow-up inspections.
For consumers, the most important step is to identify and remove any potentially contaminated cheese. People who are pregnant, adults 65 and older, and those with weakened immune systems face the highest risk of severe illness from Listeria. Symptoms can include fever, muscle aches, headache, stiff neck, confusion, loss of balance, and, in some cases, gastrointestinal issues like nausea or diarrhea. Anyone in a high-risk group who ate the recalled cheese and develops flu-like symptoms should contact a healthcare provider and mention possible Listeria exposure.
Even households that did not purchase Clover Hill products may want to review general food safety practices for soft cheeses. Public health officials routinely advise vulnerable consumers to avoid unpasteurized dairy products and to pay close attention to expiration dates and storage temperatures. As the Clover Hill investigation continues, more information about the plant’s sanitation controls and any additional recalls is likely to emerge, but the long span of illnesses already linked to this facility underscores how tenacious Listeria can be once it gains a foothold in a dairy environment.
