The USDA has warned consumers not to eat prepared meals sold at retailers including Walmart and Kroger that may contain recalled onions tied to a multistate salmonella outbreak that's sickened more than 600 people.

The U.S. Centers for Disease Control and Prevention (CDC) is investigating an outbreak of salmonella infections linked to the recalled onions that as of Friday has sickened a total of 640 ill people have now been reported from 43 states. 85 people have been hospitalized. 

The Public Health Agency of Canada reported 239 cases with 29 hospitalizations as of Friday. No deaths have been reported in Canada or the United States.

The public health alert from the USDA's Food Safety and Inspection Service involves meat and poultry products made on July 30 and July 31 by California-based Taylor Farms.

The USDA warning follows an August 1 recall by Thomson International of all red, yellow, white and sweet yellow onions shipped nationwide starting May 1 to the present.

Onions were distributed to wholesalers, restaurants, and retail stores in all 50 states and the District of Columbia, under these brand names: Thomson Premium, TLC Thomson International, Tender Loving Care, El Competitor, Hartley’s Best, Onions 52, Majestic, Imperial Fresh, Kroger, Utah Onions, and Food Lion.

Several companies have recalled onions and foods made with recalled onions, such as chicken salad, macaroni salad, fajita stir-fry, pizza, sub sandwiches, diced raw onions and peppers, and other salads. 

Potential onion shortage in Canada amid salmonella outbreak

Meanwhile, Keith Warriner, a food science professor at Canada's University of Guelph, reportedly onions and related products may be hard to come by in the grocery aisle out of an abundance of caution about potential cross-contamination.