Nearly 56,000 pounds of frozen blueberries are under recall after federal regulators flagged a potential Listeria monocytogenes contamination.

Oregon Potato Company LLC initiated the recall earlier this month. Days later, the U.S. Food and Drug Administration elevated the action to a Class I recall — the agency’s most serious classification — meaning there is a reasonable probability that exposure could cause severe illness or death, CBS News reports.

According to Prevention, the recall involves 55,689 pounds of individually quick-frozen blueberries packaged in 30-pound cases and 1,400-pound totes. The product was shipped to commercial buyers in Michigan, Oregon, Washington, Wisconsin, and parts of Canada.

The FDA recall involves 55,689 pounds of frozen blueberries.

Why Listeria Raises Alarm

Listeria is not an ordinary foodborne bacterium. It can survive freezing temperatures and continue to grow in refrigerated environments.

For healthy adults, symptoms may include fever, nausea, diarrhea, or muscle aches. For vulnerable groups — including older adults, pregnant people, newborns, and those with weakened immune systems — the infection can become invasive, leading to stiff neck, confusion, loss of balance, or convulsions, Good Housekeeping explains.

Pregnant individuals face heightened danger. Infection during pregnancy can result in miscarriage, stillbirth, or life-threatening illness in newborns, health experts told ClickOnDetroit.

Symptoms can surface within hours. In some cases, they take weeks to appear.

The affected states include Michigan and Oregon.

Where the Product Went

The recalled blueberries were distributed primarily at the wholesale level. Food service companies and manufacturers were among the recipients, Huron Daily Tribune reports.

Regulators have not confirmed any illnesses linked to the affected lots. Still, the Class I designation signals urgency. The FDA reserves that category for recalls involving products that pose a serious health hazard.

Businesses that received the blueberries have been urged to stop using the product and either discard it or return it to the supplier.

The blueberries were packaged in bulk containers.

What Consumers Should Know

Even though the recalled berries were not sold in grocery stores, health officials advise caution.

Anyone who believes they may have been exposed and develops symptoms consistent with listeriosis should seek medical attention. Early treatment with antibiotics can reduce complications, particularly for high-risk individuals.

Frozen fruit is often viewed as low risk. This recall serves as a reminder that pathogens do not disappear in cold storage.

Food safety officials continue monitoring the situation as the supply chain works to remove the product from circulation.