MONDAY, Sept. 29, 2025 (HealthDay News) — Federal health officials have expanded their probe into a listeria outbreak that has claimed four lives, and affected at least 20 people.

The investigation, which first focused on premade chicken pasta meals sold at Walmart and Kroger, is now looking at a similar product sold at Trader Joe’s.

The outbreak, which has spread across 15 states, was initially tied to Marketside and Home Chef brand chicken fettuccine Alfredo meals sold at Walmart and Kroger. The products were previously recalled in June.

Recent genomic testing by one of the producing companies traced the source of contamination to pasta from Nate's Fine Foods, according to a status report posted online Sept. 25 by the U.S. Centers for Disease Control and Prevention (CDC).

This week, Albertsons-owned stores also recalled some deli-made items that contained a recalled bow-tie pasta from Nate's.

Now, a newer alert from the U.S. Food Safety and Inspection Service (FSIS) has added two new products to the list of potentially contaminated frozen meals:

• Marketside Linguine with Beef Meatballs & Marinara Sauce (12-ounce trays) sold at Walmart, with  “Best By” date of Sept. 22, 24, 25, 29 or 30 and Oct. 1, 2025. The product has establishment number "EST.50784" or "EST.47718" inside the USDA inspection mark.

• Trader Joe’s Cajun-Style Blackened Chicken Breast Fettuccine Alfredo (16-ounce trays) with a “Best By” date of Sept. 20, 24 or 27, 2025 on the front label. It has establishment number "P-45288" inside the USDA inspection mark.

The alert identifies California Ranch Food Company, which makes products for Trader Joe's, as part of the recall.

A Walmart spokesperson confirmed that the company has removed the product from its shelves and is cooperating with the supplier’s investigation.

FreshRealm detected the listeria strain in the Walmart linguine product during testing.

In a statement, the company said it has been "relentless in our approach to get to the bottom of this and now we have an answer."

The findings confirmed what FreshRealm suspected all along, the statement said: "The Listeria outbreak strain traced back to an ingredient supplied by a third party."

Results of its testing have been shared with federal regulatory agencies, including the U.S. Department of Agriculture (USDA), U.S. Food and Drug Administration and CDC.

FreshRealm, which said "this is clearly an evolving situation," said customers who bought the products should throw them out or return them.

The outbreak’s toll has grown significantly since June, when 17 cases and three deaths were reported.

The CDC has since confirmed three more cases, including another death, bringing the total number of confirmed cases to 20 and deaths to four.

All but one of the sick individuals were hospitalized.

Listeria infection, or listeriosis, can be particularly dangerous for vulnerable populations, including pregnant women, newborns, older adults and those with weakened immune systems. Symptoms can include fever, muscle aches, headache and confusion. They typically appear within two weeks of consuming tainted food, according to FSIS.

Health officials are continuing their investigation into the outbreak and the source of the contamination.

More information 

The U.S. Centers for Disease Control and Prevention provides additional information on listeriosis outbreaks and prevention.

SOURCES: The New York Times, Sept. 27, 2025; U.S. Food Safety and Inspection Service, public health alert, Sept. 25, 2025; FreshRealm, statement, Sept. 30, 2025