The FDA has upgraded a walnut recall to Class I, its most severe category, Newsweek reports. The new classification warns that consumption of the product could potentially cause "serious adverse health consequences or death."

Indio, California-based Stutz Packing Company last month issued a voluntary recall of 1-pound packages of shelled walnuts, after routine sampling found Listeria monocytogenes, a bacteria that can cause food poisoning. Stutz said just over 2,500 cases were distributed to food bank warehouses in Arizona and Texas.

The company said it has stopped production and distribution of the products and will continue to work with the FDA to investigate the contamination. Stutz added that no other walnut products are affected and no illnesses have been reported.

The FDA's move comes less than a week after the CDC announced a third death in connection with a nationwide listeria outbreak in Boar's Head deli meats. The deaths occurred in Illinois, New Jersey, and Virginia. Forty-three other people in 13 states have been hospitalized due to the outbreak.

Boar's Head last month recalled some 7 million pounds of deli meat, covering 71 products made between May 10 and July 29 under the Boar's Head and Old Country brand names. They include liverwurst, ham, beef salami, bologna, and other products made at the company's Jarratt, Virginia, plant.

Listeria can cause listeriosis, a bacterial infection that can lead to severe illness and death. It can also spread to the nervous system and cause meningitis and sepsis.

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