Butterball LLC issued a voluntarily recall of more than 78,000 pounds (35,400 kilograms) of raw ground turkey products nationwide Thursday as Wisconsin health officials investigate four salmonella cases in the state.

The U.S. Department of Agriculture's Food Safety and Inspection Service said the prepackaged ground turkey was produced on July 7, 2018, and the agency is worried some consumers may still have them in their freezers.

"Consumers who have purchased these products are urged not to consume them," the agency said in a statement. "These products should be thrown away or returned to the place of purchase."

The products had a sell- or freeze-by date of July 26, 2018.

The Wisconsin Department of Health Services said the four patients have the same strain of salmonella and are linked to the Butterball ground turkey products being recalled. A Minnesota resident who reported eating ground turkey has the same strain of salmonella as the Wisconsin cases, but the brand of the product consumed is unknown, health officials said.

Butterball is based in Mount Olive, North Carolina.

The Department of Agriculture, Trade, and Consumer Protection and local health departments are aiding in the investigation by state health officials. The Centers for Disease Control and Prevention is also investigating.

The products being recalled have establishment number "EST. P-7345" in the USDA mark of inspection. The products were shipped to retail locations nationally.

Salmonella can cause salmonellosis, a bacterial foodborne illness with symptoms including fever, diarrhea and abdominal cramps.