In February 2021, CDC, public health and regulatory officials in several states, and the U.S. Food and Drug Administration (FDA) began investigating a multistate outbreak of Listeria monocytogenes infections. Epidemiologic and laboratory data showed that queso fresco cheeses made by El Abuelito Cheese Inc. were contaminated with Listeria and made people sick.

A total of 13 people infected with the outbreak strain of Listeria monocytogenes were reported from 4 states. Illnesses started on dates ranging from October 20, 2020, to March 17, 2021, with 12 illnesses occurring in 2021. Twelve people were hospitalized, and one death was reported from Maryland. Four people got sick during their pregnancy, resulting in two pregnancy losses and one premature birth; the fourth person remained pregnant after recovering.

State and local public health officials interviewed people about the foods they ate in the month before they got sick. Of the 11 people interviewed, eight (73%) people reported eating Hispanic-style fresh and soft cheeses. Among the eight people, seven (88%) reported eating queso fresco – four specifically reported brands made by El Abuelito Cheese Inc, including El Abuelito brand and Rio Grande brand.

Connecticut officials collected samples of El Abuelito brand Hispanic-style fresh and soft cheeses for testing from a store where a sick person reported buying these types of cheeses. On February 19, WGS showed that the Listeria bacteria in El Abuelito brand queso fresco were closely related to the Listeria bacteria from sick people in this outbreak. This means that people likely got sick from eating this cheese.

On February 19, El Abuelito Cheese Inc. recalled all queso fresco products made at their facility. They also stopped producing and distributing all their products. On February 27, El Abuelito Cheese Inc. expanded their recall to include all quesillo and requeson products that were made or packed at the same facility as the contaminated queso fresco.

The outbreak was declared over on May 14, 2021.