At least 20 people have been infected, and four have died,in a Listeria outbreaktied to ready-to-eat pasta meals sold nationwide. The health alert is warning consumers about contaminated products sold at Walmart and Trader Joe’s. Affected items include Marketside Linguine with Beef Meatballs & Marinara, Cajun Style Blackened Chicken Fettuccine Alfredo, and other select pasta meals with specific best-used-by dates. Officials advised checking kitchens and freezers and discarding or returning any recalled products.