The Food and Drug Administration has upgraded the recall of organic eggs sold at Costco to the highest risk level, indicating a significant risk of serious health consequences related to possible salmonella contamination.

The Class I classification by the federal agency suggests a “reasonable probability” that consumption of the affected eggs could lead to “adverse health consequences or death.”

Last month, Handsome Brook Farms conducted a voluntary recall of over 10,000 units of Kirkland Signature Organic Pasture-Raised 24-Count Eggs. Although no illnesses have been reported, customers who purchased the affected eggs are advised to return them to Costco for a full refund.

The eggs, with UPC number 9661910680 and an expiration date of January 5, were sold in Kirkland Signature-branded plastic cartons. They were primarily sold at Costco warehouses in the southern states, although the recall extends nationwide.

“Additional controls and retraining in the supply chain will be implemented to prevent a recurrence,” Handsome Brook Farms said.

It was not specified where the eggs were supposed to go.

Handsome Brook Farms, the supplier behind the Kirkland Signature brand, issued the recall on November 27, claiming: “The company determined that eggs that were not intended for retail distribution were instead packaged and distributed in retail packaging.”

The error resulted in the potential contamination of over 250,000 eggs.

Salmonella infections can cause symptoms such as diarrhea, abdominal cramps, fever and nausea. While serious complications are rare, young children, older adults and people with weakened immune systems are more susceptible. In some cases, salmonella can cause serious illness or death.

Customers who purchased the affected eggs should check the UPC number and expiration date. If your eggs are part of the recall, you should either throw them away or return them to Costco for a refund.

For more information about the recall and affected products, Costco shoppers are encouraged to consult the retailer’s website or contact their local store.