By Lisa L. Gill, Consumer Reports Investigative Reporter
Listeriosis is a relatively uncommon infection caused by the bacteria listeria. However, it poses special concerns during pregnancy because pregnant women are 10 times more likely to get a listeriosis infection than other adults.
Pregnant Hispanics face an even larger threat: They are 24 times more likely to develop listeriosis. That’s because certain soft cheeses often made from unpasteurized milk, such as queso fresco and cotija, are prone to listeria contamination and are common in many Latino households.
The consequences of a listeriosis infection are serious: About 20 percent of pregnant people infected with it will lose their baby, according to the American College of Obstetricians and Gynecologists.
The list of foods prone to listeria contamination is long because listeria is a hardy bacteria that spreads easily. It thrives in the cold, damp environment of food processing plants, and can live almost indefinitely on many surfaces. Once it contaminates machinery in a food processing plant or the equipment at a grocery store, it is very difficult to eliminate.
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Though avoiding such a wide variety of foods may sound daunting, Consumer Reports recommends focusing on the foods known to pose the highest risk:
- Deli Meat, Prepared Deli Salads, and Hot Dogs: The preparation and packaging equipment—such as slicers, knives, and cutting boards—can harbor listeria. You should skip these altogether during pregnancy. If you do consume them, heat them to 165° F.
- Raw Spinach and Leafy Greens: Listeria can get into irrigation water on a farm where the greens are grown, or farm or wild animals can contaminate the plants as well. But because leafy greens are packed with vitamins and nutrients, you don’t want to avoid them altogether. Instead, consider consuming greens like spinach, kale, and collard greens that can be cooked.
- Soft Cheeses: The riskiest soft cheeses are made with unpasteurized, raw milk, so you should always check the label. The problem is that soft cheeses have a high water content and low acidity, which allows listeria to thrive. Some examples are Brie, queso fresco, queso blanco, queso blanco, queso ranchero, and cuajada en terrón.
- Refrigerated Meat Spreads and Pâté: Either skip these or find meat spreads and pâté that do not need refrigeration before opening, such as products in cans, jars, or sealed pouches. These sealed products are heat-treated to kill germs and then sealed in airtight containers. However, once you open these foods, store them in the refrigerator.
- Raw and Smoked Seafood: Raw and smoked seafood aren’t heated enough to kill listeria. This includes ceviche, sushi, sashimi, raw shellfish, and fish marked as nova-style, lox, kippered, smoked, or jerky.
- Alfalfa Sprouts and Bean Sprouts: These sprouts are susceptible to listeria because the cultivation conditions, a moist, warm environment, can also foster bacteria growth, including listeria. If you decide to eat these, heat the sprouts to the point they’re steaming to kill any potential listeria.
*This is a condensed version of a Consumer Reports story from May 2024. Visit ConsumerReports.org for the full story.