Potato salad sold under the Coborn’s, Cash Wise and Midwest Pride brands in Minnesota and six other states may be contaminated with Listeria monocytogenes bacteria, the Minnesota Department of Agriculture warned Friday.

The potato salad was sold in two forms:

# Prepackaged one-pound containers with lot number 7057018A sold under the Midwest Pride, Coborn’s and Cash Wise labels. The Midwest Pride product had an expiration date of April 2. The other two brands had expiration dates of March 9.

# Deli-packed containers sold under lot codes 7057018A and 7057026B from Feb. 27 to March 16 in 89 stores in Minnesota, North Dakota, South Dakota, Wisconsin, Iowa, Michigan and Nebraska.

While there have been no reports of illnesses associated with the products, DBC Foods of St. Cloud manufactured the potato salad and has issued a voluntary recall. The company and the state agency advise customers to return the product for a full refund.

Kevin Elfering, director of the dairy and food division of the Agriculture Department, said the contamination was first detected in a product sample during a routine store inspection.

"When we came across it, we wanted to do the right thing by our customers," said Steve Gottwalt, spokesman for DBC Foods.

Elfering said state investigators were trying to determine the source of the contamination.

Eating food contaminated with the Listeria bacteria can cause an uncommon but potentially serious disease marked by nausea, fever, severe headache and neck stiffness. Infants, the elderly and those with weakened immune systems are most susceptible.