At least four deaths and 19 hospitalizations have been linked to frozen ready meals contaminated with listeria, according to health officials. The Centers for Disease Control and Prevention (CDC) issued a warning after pasta meals sold at Kroger, Walmart, and Trader Joe’s were found to be tainted.

The contamination stems from chicken fettuccine Alfredo meals produced by New Jersey-based FreshRealm, which were distributed nationwide under the brands Marketside and Home Chef. The affected products include beef meatball marinara linguine and chicken fettuccine alfredo meals. While all compromised items have been recalled, health authorities caution that some may still be stored in home freezers or refrigerators.

The CDC emphasized that the true scale of the outbreak is likely higher than reported, as many cases go undiagnosed. Some individuals recover without medical attention and are not tested for listeria, while recent illnesses may take three to four weeks to confirm as part of the outbreak. Deaths have been confirmed in Illinois, Michigan, Texas, and Utah, with officials noting the outbreak could extend beyond these states.

The U.S. Department of Agriculture’s Food Safety and Inspection Service issued a public health alert, urging consumers with the affected products to discard them or return them to retailers. Walmart stated it removed the items from stores and is investigating the contamination, while FreshRealm confirmed listeria was detected in its linguine product supplied by a third party. Trader Joe’s did not immediately respond to requests for comment.

FreshRealm previously urged customers to destroy recalled products and reiterated its commitment to food safety as investigations continue.