Federal officials are investigating a deadly outbreak of Listeria infections traced to certain cheese products made by Modesto, CA-based Rizo-López.

The outbreak began in 2014 with the most recent patient having become sick in December 2023. At least two people have died. On Monday, Feb. 5, Rizo-López recalled 61 products in connection with the outbreak, according to the Centers for Disease Control and Prevention.

As of Feb. 6, there have been 26 people confirmed as outbreak patients, with 23 having been hospitalized. The patients are stretched across 11 states.

Most recently recalled products were sold nationwide under these brands and at deli counters:

  • Campesino
  • Casa Cardenas
  • Don Francisco
  • Dos Ranchitos
  • El Huache
  • Food City
  • La Ordena
  • Rio Grande
  • Rizo Bros
  • San Carlos
  • Santa Maria
  • Tio Francisco
  • 365 Whole Foods Market

“CDC investigated this outbreak in 2017 and 2021. Epidemiologic evidence in previous investigations identified queso fresco and other similar cheeses as a potential source of the outbreak, but there was not enough information to identify a specific brand. CDC reopened the investigation in January 2024 after new illnesses were reported in December 2023 and the outbreak strain was found in a cheese sample from Rizo-López Foods,” according to the outbreak announcement posted today.

“The true number of sick people in this outbreak is likely higher than the number reported, and the outbreak may not be limited to the 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 be reported as it usually takes 3 to 4 weeks to determine if a sick person is part of an outbreak.”

Investigators from the CDC and the Food and Drug Administration are interviewing patients about what foods they ate before they became sick. This can be difficult because it can take up to 70 days for symptoms of Listeria infection to appear after ingestion of the pathogen.

Of the 22 people interviewed, 16 reported eating queso fresco, cotija, or other similar cheeses. Among people who remembered specific brands, three people who got sick between 2014 and 2022 reported Don Francisco brand queso fresco or cotija. Don Francisco is one of the brands of recalled cheeses.

The sick people range in age from less than 1 year old to 88 years old, with 58 percent being female. The sick people live from coast to coast.

Public health officials are using a nationwide database to help locate patients.

Whole genome sequencing showed that bacteria from sick people’s samples from 2014 to present are closely related genetically. This suggests that people in this outbreak got sick from the same food.

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 U.S. FDA conducted inspections at the Rizo-López Foods facility and collected food and environmental samples for testing. The FDA found the outbreak strain of Listeria on a container where cheeses are kept before they are packaged.

On Jan. 11 this year Rizo-López Foods, Inc. recalled the aged cotija cheese product after Hawaii state officials found Listeria in it. On Feb. 6, 2024, Rizo-López Foods, Inc. recalled all cheese and other dairy products made in their facility. They have also temporarily stopped producing and distributing these products while their investigation is ongoing.

About Listeria infections
Food contaminated with Listeria monocytogenes may not look or smell spoiled but can still cause serious and sometimes life-threatening infections. Anyone who has eaten any recalled products and developed symptoms of Listeria infection should seek medical treatment and tell their doctors about the possible Listeria exposure.

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

Symptoms of Listeria infection can include vomiting, nausea, persistent fever, muscle aches, severe headache, and neck stiffness. Specific laboratory tests are required to diagnose Listeria infections, which can mimic other illnesses. 

Pregnant women, the elderly, young children, and people such as cancer patients who have weakened immune systems are particularly at risk of serious illnesses, life-threatening infections, and other complications. Although infected pregnant women may experience only mild, flu-like symptoms, their infections can lead to premature delivery, infection of the newborn, or even stillbirth.

(To sign up for a free subscription to Food Safety News,click here)