WASHINGTON, D.C.: Federal health officials are urging consumers not to eat certain ready-to-heat pasta meals sold at Walmart and Trader Joe's because they may be contaminated with listeria, the same bacteria linked to a deadly outbreak earlier this year.

On September 26, the U.S. Department of Agriculture (USDA) expanded a public health alert to include Trader Joe's Cajun Style Blackened Chicken Breast Fettuccine Alfredo, sold in 16-ounce plastic trays with best-by dates of September 20, 24, and 27. The meals carry the establishment number P-45288 inside the USDA inspection mark and may still be in customers' refrigerators.

The day before, the USDA issued a warning for Marketside Linguine with Beef Meatballs & Marinara Sauce, sold at Walmart in refrigerated 12-ounce clear plastic trays. Those meals, marked with EST. 50784 and EST. 47718, have best-by dates ranging from September 22 through October 1, and were shipped nationwide.

No recall has been announced, but the distributor, FreshRealm, said it advised Walmart to pull the products from shelves. Walmart confirmed it stopped sales and removed the meals from stores. Additional products may also be identified, according to USDA's Food Safety and Inspection Service.

The alert stems from testing that detected listeria in linguine used in the Walmart meatball dish. FreshRealm said the strain matched the bacteria responsible for a summer outbreak linked to chicken fettuccine Alfredo sold at Walmart and Kroger, which killed four people and sickened at least 20. "We have long maintained that the source of the listeria was likely an ingredient supplied by a third party," the company said. The pasta came from Nate's Fine Foods of Roseville, California, which has not commented on it.

Listeria infections can be severe, particularly for older adults, pregnant women, newborns, and people with weakened immune systems. Symptoms include fever, muscle aches, stiff neck, confusion, and loss of balance. The CDC estimates listeria causes 1,600 illnesses and about 260 deaths annually in the U.S. Federal officials say they are tightening food-safety protocols following multiple high-profile outbreaks, including one tied to Boar's Head deli meats last year that killed 10 people and sickened more than 60.