CDC declares deadly Listeria outbreak over; cheese from Rizo-López was the cause

Federal officials say the decade-long Listeria outbreak is over. Two people died as a result of their infections.

The Food and Drug Administration and the Centers for Disease Control and Prevention investigated the outbreak. It began in June 2014 and lasted through December 2023. A total of 26 people in 11 states were confirmed as outbreak patients; 23 of them had to be hospitalized. Also, two people became ill during their pregnancies and one person had a pregnancy loss. There were also two newborns with Listeria infections.

Of the 22 patients interviewed, 73 percent reported eating queso fresco, cotija or other similar cheeses.

Epidemiological and laboratory data showed that queso fresco and cotija cheese made by Rizo-López Foods made people sick during this outbreak. Many foods, including cheese, crema and yogurt, were recalled. Recalled foods are past their expiration dates. See the FDA page for this retrieve messages. All recalled products have exceeded their expiration dates.

“The actual number of sick people in this outbreak was likely higher than the reported number, and the outbreak may not have been limited to states with known illnesses. This is because some people recover without medical care and are not tested for Listeria. In addition, recent illnesses may not yet have been reported, as is usually the case 3 to 4 weeks to determine if a sick person is part of an outbreak,” according to the CDC outbreak update.

Public health researchers took advantage of the PulseNet system to identify diseases that may have been part of this outbreak. CDC PulseNet maintains a national database of DNA fingerprints of bacteria that cause foodborne illness. DNA fingerprinting is performed on bacteria using a method called whole genome sequencing.

Whole genome sequencing has shown that bacteria from samples taken from sick people from 2014 to the present are genetically closely related. This suggested that people in this outbreak were getting sick from the same foods.

In January 2024, the Hawaii State Department of Health’s Food and Drug Branch collected a sample of aged cotija cheese product made by Rizo-López Foods during routine sampling. Testing identified the outbreak strain of Listeria in the product.

The FDA conducted inspections at the Rizo-López Foods plant and collected food and environmental samples for testing. The FDA found the outbreak strain from two environmental samples collected at the facility.

About Listeria infections
Food contaminated with Listeria monocytogenes may not look or smell putrid, but it can still cause serious and sometimes life-threatening infections. Anyone who has eaten a recalled product and developed symptoms of a Listeria infection should seek medical attention and tell their doctor about the possible exposure to Listeria.

Also, anyone who has eaten any of the recalled products should monitor themselves for symptoms in the coming weeks, as it can take up to 70 days after exposure to Listeria for symptoms of listeriosis to develop.

Symptoms of a Listeria infection may include vomiting, nausea, persistent fever, muscle aches, severe headaches, and neck stiffness. Specific laboratory tests are needed to diagnose Listeria infections, which can mimic other diseases.

Pregnant women, the elderly, young children and people such as cancer patients with weakened immune systems are at particular risk of serious illness, life-threatening infections, other complications and death. Although infected pregnant women may experience only mild, flu-like symptoms, their infections can lead to preterm labor, infection of the newborn, or even stillbirth.

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