The USDA warns certain salads sold at Walmart, Kroger, and H-E-B contain onions linked to a salmonella outbreak that has sickened more than 500 people

• The USDA is warning against consuming certain products containing onions that are currently subject to a recall.
• A salmonella outbreak believed to be linked to Thomson International's red onions is currently under investigation. At least 516 people were reported ill as of Monday.
• The USDA released a list of prepackaged foods sold at Walmart, Kroger, and H-E-B that contain the recalled onions.

The US Department of Agriculture's Food Safety and Inspection Service issued a health alert on Wednesday about some prepackaged foods that contain onions believed to be the source of an ongoing salmonella outbreak.

The products include a Southwest-style salad with chicken sold at Walmart and a cheddar cheese and chicken salad tray sold at Kroger.

The Food and Drug Administration is currently investigating the cause of a salmonella outbreak that had sickened at least 516 people in the US as of Monday. In Canada, 120 people were sick as of Sunday.

Onions produced by Bakersfield, California-based Thomson International are being recalled in the US and Canada because of potential salmonella contamination.

The outbreak is believed to be linked to Thomson International's red onions, but the producer is also recalling yellow, sweet yellow, and white onions due to the potential of cross-contamination, the FDA said.

Thomson International's onions were shipped to grocery stores including Walmart and Kroger in all 50 states. They were sold under brand names including: Thomson Premium, TLC Thomson International, Tender Loving Care, El Competitor, Hartley's Best, Onions 52, Majestic, Imperial Fresh, Kroger, Utah Onions, and Food Lion.

"FDA recommends that anyone who received or suspects having received onions from Thomson International, Inc. use extra vigilance in cleaning and sanitizing any surfaces and containers that may have come in contact with these products to reduce the risk of cross-contamination," the agency said in a statement. "This includes cutting boards, slicers, countertops, refrigerators, and storage bins."

The USDA's health alert advises people not to consume products that could contain the contaminated onions. The products included in the alert were shipped to stores in Arkansas, Louisiana, Mississippi, Oklahoma, and Texas.

Here's the full list of products that the USDA is warning include the recalled onions:

• Sold at Walmart: Plastic-sealed, 7.25 ounce, container labeled "Sausage Breakfast Scramble Bowl" with lot code TFD212AU8 or TFD213AU8 and best if used by 08/06/2020 or 08/07/2020.
• Sold at Kroger: Plastic-sealed, 6.2 ounce, container labeled as "Taylor Farms Cheddar Cheese & Chicken Salad Snack Tray" with use by date 08/06/20 or 08/07/20 and lot code TFD212AU7 and TFD213AU7.
• Sold at Kroger: Plastic bags containing a 41.35-ounce "Chicken Salad" with use by date 08/04/20 or 08/05/20 and lot codes TFD212AU8 and TFD213AU8.
• Sold at Walmart: Plastic-sealed, 10 ounce, container labeled as "Chicken Salad Deli Snack" with lot codes TFD212AU3 and TFD213AU3 with best by dates 08/06/2020 or 08/07/2020.
• Sold at H-E-B: Plastic-sealed, 7.75 ounce, container labeled as "H.E.B. Shake Rattle Bowl SOUTHWEST SALAD with CHICKEN" and a best if used by date of Aug 10/2020 and lot code TFD213AU20.
• Sold at Walmart: Plastic-sealed, 17.25 ounce, container labeled as "Marketside SOUTHWEST STYLE SALAD WITH CHICKEN" with a best if used by date of 08/11/20 or 08/12/2020 and lot codes TFD212AU26 or TFD213AU26.