Kroger Co. said on Wednesday that it is voluntarily recalling all ground beef products with sell-by dates between May 21 and June 8, owing to fears of E. coli contamination. The bacteria have stricken at least 35 people.

The recall includes all varieties and weights of products sold at the Kroger stores throughout Michigan and in central and northern Ohio (Columbus and Toledo areas).

The recall follows a notification by the state and federal health authorities that E. coli illnesses reported in Michigan and in Central and Northern Ohio have been linked to ground beef products sold in some Kroger stores in those regions.

The Cincinnati-based supermarket chain continues to work with local, state and federal health authorities to discover the provider of the specific type of ground beef that may have caused the illnesses. The specific meat source could not be yet identified as the grocer uses several large suppliers.

It has asked the customers to return ground beef products bought between May 21 and June 8 regardless of packaging, to the stores for a full refund or replacement. "If you have ground beef in the freezer that you are the least concerned about, please bring it back and we will refund your money," said Dale Hollandsworth, a spokesman for Kroger.

The USDA Food Safety and Inspection Service said none of the infected product remains in stores. "The health department has done several testings and samplings to make sure that the ground beef is safe," Hollandsworth said of current product in the stores. "We're very confident that the ground beef is safe."

For any queries regarding the recall, consumers may contact Kroger toll-free at (800) 632-6900.

Health officials reminded the consumers that proper handling, storage and cooking of ground beef offers the best protection against food-borne illness. Consumers are recommended to cook all ground beef to an internal temperature of at least 160 degrees Fahrenheit to kill any potential bacteria.

Eating rare and undercooked meat can lead to E. coli infection, which can cause stomach cramps, vomiting, and diarrhea. In extreme cases, it can lead to kidney failure and death.