Listeria can grow in cold environments, even the refrigerator, experts say.
CNN  — 

A deadly outbreak of listeria in 11 states has been linked to dozens of dairy products, including popular Super Bowl snacks queso fresco and Cotija cheese, the US Centers for Disease Control and Prevention has announced. But what can you do reduce your risk of becoming infected?

What to know

Listeria is a hardy germ, so determined to stick around that it can continue to grow while refrigerated, which even fellow bacterial villains salmonella and E. coli cannot do.

In the United States, listeria is the third leading cause of death from foodborne illness, killing about 260 a year, according to the CDC.

“Even with adequate antibiotic treatment, the disease has a high mortality rate” of 20% to 30%, the US Food and Drug Administration said.

Adults and children with healthy immune systems may simply develop a mild or unpleasant illness that will not require hospitalization or antibiotics. However, anyone immunocompromised, such as older adults, organ transplant patents, those with cancer or kidney disease, diabetes or people with HIV/AIDS, can become seriously ill and die.

Pregnant people are about 10 times more likely to become sick from listeria, and the illness can be fatal to the fetus. Pregnant Hispanics are at highest risk, likely due to eating traditional soft cheeses such as queso fresco and other foods made with milk that is unpasteurized, the FDA said. Foods made with raw milk are 50 to 160 times more likely to contain listeria, the agency said.

The CDC said it is aware of 26 people from 11 states who have been infected with the current outbreak strain of listeria between June 2014 and December 2023. The two deaths associated with the infections were reported in California and Texas.

Recent interviews with sick people and facility screenings led the CDC to identify queso fresco and Cotija cheese made by Rizo-López Foods as the source of the illnesses.

Deli meat and hot dogs were a common source of listeria outbreaks in the 1990s, according to the CDC, likely because of the difficulty in cleaning the resistant bacteria from every nook and cranny in deli food preparation devices.

However, listeria outbreaks have been linked to cantaloupe, celery, ice cream, leafy greens such as spinach, soft cheeses and sprouts, the agency said.

How to protect yourself

Keep the kitchen clean: Clean your refrigerator regularly with hot water and liquid soap. Prepare meats and vegetables separately and be sure to sanitize food preparation areas, the CDC said.

Keep the fridge cool: Because listeria can easily grow in cool temperatures, keep your refrigerator at 41 degrees Fahrenheit (5 degrees Celsius) or lower. The freezer should be at zero Fahrenheit (minus 18 degrees Celsius) or lower.

Raw milk: Eating foods made from raw milk is “one of the riskiest” ways to become infected with listeria and other harmful germs, the CDC said.

Soft cheese: If you are pregnant or at high risk, don’t eat soft cheeses, “such as queso fresco, queso blanco, panela (queso panela), brie, Camembert, blue-veined, or feta, unless it is labeled as made with pasteurized milk,” the CDC said.

However, know that some soft cheeses have been contaminated during cheese making, the agency said.