Using whole genome sequencing (WGS), the U.S. Centers for Disease Control and Prevention (CDC), the U.S. Food and Drug Administration (FDA), and public health and regulatory officials in several states recently solved a multistate foodborne illness outbreak investigation that has been ongoing since 2014, with the most recent illnesses being reported in December 2023.

CDC first investigated this outbreak of illnesses caused by Listeria monocytogenes in 2017, and again in 2021. Epidemiologic evidence in previous investigations identified queso fresco and other similar cheeses as a potential source of the outbreak, but there was not enough information to identify a specific brand. CDC reopened the investigation in January 2024 after new illnesses were reported in December 2023 and the outbreak strain was found in a cheese sample from Rizo-López Foods in Hawaii.

Using CDC’s PulseNet system, which houses a national database of foodborne pathogen DNA fingerprints identified through WGS, public health investigators found L. monocytogenes isolated from patients in 2014 to be closely related to isolates from more recent patients. The genetic similarity suggests that the people sickened in 2014–2023 were infected by the same food.

During routine sampling in January 2024, the Hawaii State Department of Health’s Food and Drug Branch collected a sample of aged cotija cheese product made by Rizo-López Foods, which tested positive for the strain of L. monocytogenes responsible for the outbreak. Subsequently, FDA conducted inspections at the Rizo-López Foods facility and collected food and environmental samples for testing. FDA found the outbreak strain of L. monocytogenes on a container where cheeses are kept before they are packaged.

As of February 6, 2024, a total of 26 people infected with the outbreak strain of L. monocytogenes have been reported from 11 states (Arizona, California, Colorado, Florida, Georgia, Nevada, North Carolina, Oregon, Tennessee, Texas, and Washington), resulting in 23 hospitalizations and two deaths. The onset of illnesses ranges from June 15, 2014–December 10, 2023.

State and local public health officials are interviewing case patients about the foods they ate in the month before they got sick. Of the 22 people interviewed, 16 (73 percent) reported eating queso fresco, cotija, or other similar cheeses. Among people who remembered specific brands, three people who got sick between 2014–2022 reported Don Francisco brand queso fresco or cotija. Don Francisco is one of the brands of cheeses produced by Rizo-López Foods, which has been recalled.

On January 11, 2024, Rizo-López Foods recalled the aged cotija cheese product that tested positive for L. monocytogenes, and on February 6, 2024, after FDA found the outbreak strain in the facility, the business recalled all cheese and other dairy products produced at that location.

Update, February 9, 2024: FDA has been notified of additional recalls for products made with or containing recalled dairy products from Rico Lopez Foods, issued by Simply Fresh, Trader Joe's, and Fresh Creative Foods.

Update, February 12, 2024:  FDA has been notified of additional recalls for products made with or containing recalled dairy products from Rico Lopez Foods, issued by BrightFarms Inc., Ready Pac Foods Inc., Dole Fresh Vegetables Inc., and Albertsons Companies. The U.S. Department of Agriculture's Food Safety and Inspection Service (USDA-FSIS) has also issued a public health alert for "Amazon Kitchen, chicken Chile Verde burrito with rice, black beans, and Monterey jack."

Update, February 15, 2024: More items that have been made with dairy products from Rico Lopez Foods have been added to the recall list, which can be viewed on FDA's continually updated table of recalled products. FDA’s onsite inspection of Rico Lopez Foods' production facility is still ongoing; however, an additional environmental sample collected during that inspection has tested positive for L. monocytogenes. WGS analysis of that sample showed that it is the same strain of L. monocytogenes that is causing illnesses in the outbreak.

Update, February 21, 2024: FDA released a list of Retail Establishments That Received Rizo-López Foods Dairy Products that includes over 100 retailers across seven states. FDA continues to update its table of recalled products