What to Know About the Listeria Outbreak: Food Poisoning Risk and Recalls

This week, the Centers for Disease Control and Prevention announced an expanded recall of dairy products and other foods that may have been contaminated with the bacteria Listeria monocytogenes.

The recalled products — all with ingredients manufactured by the California-based Rizo López Foods — include cheese, yogurt, sour cream, salad dressings and kits and other foods that use Rizo López’s products. They have been sold under many brand names and by many supermarkets, including Trader Joe’s, Whole Foods Market and Marketside.

Most people who ingest listeria don’t get very sick, if they develop symptoms at all. But certain high-risk individuals can fall seriously ill. Approximately 1,600 people in the United States develop serious listeria infections, known as listeriosis, every year — and about 260 of those infections are fatal, said Laura Gieraltowski, an epidemiologist with the C.D.C.’s outbreak response and prevention branch.

In the current outbreak, there have been 26 confirmed cases across 11 states, including 23 hospitalizations and two deaths.

Here’s what you need to know about listeria to stay safe.

How does listeria end up in food?

Listeria bacteria are naturally found in the soil, which means they also end up on or inside things that come into contact with the soil, such as plants and animals.

“We find it pretty much everywhere in nature when we look for it,” said Catherine Donnelly, an emeritus professor at the University of Vermont who has studied listeria for decades.

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