Listeria (Food Safety for Moms-to-Be)
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What Is Foodborne Illness? | Listeria | Toxoplasma
Frequently Asked Questions
"What is Listeria monocytogenes?"
Listeria monocytogenes (L. monocytogenes) is a harmful type of bacteria that can be found in refrigerated, ready-to-eat foods such as meat, poultry, seafood, dairy, and produce. Like other harmful bacteria, it thrives in unsanitary food production conditions, leading to contamination of the food. However, unlike many other foodborne bacteria, L. monocytogenes can grow in cold temperatures, including inside refrigerators. Animals can also carry L. monocytogenes without showing symptoms, leading to the bacteria’s presence in animal-derived foods. When eaten, L. monocytogenes-contaminated food may result in a disease called listeriosis.
Listeriosis in pregnant people can lead to serious complications with their pregnancy, including miscarriage, stillbirth, premature delivery, and death.
"How could I get listeriosis?"
You can get listeriosis by eating raw, unpasteurized milk and unpasteurized milk products, certain types of cheeses, like pasteurized or unpasteurized queso fresco-type cheeses, raw or processed vegetables, raw or processed fruits, raw or undercooked poultry, sausages, hot dogs, deli meats, ice cream, raw or smoked fish and other seafood. L. monocytogenes has also been found in raw pet food.
Listeriosis is a life-threatening disease, especially for unborn or newborn children, adults over the age of 65, and those with weakened immune systems.
"How could listeriosis affect me?"
Listeriosis symptoms can appear after a few days or weeks, and may include fever, muscle aches, nausea, vomiting, diarrhea, headache, stiff neck, confusion, loss of balance, and convulsions.
While a pregnant person may have only a mild, flu-like illness, or may not feel sick at all, listeriosis can lead to miscarriage, death of the unborn baby, a low-birth-weight infant, health problems for the newborn, or even infant death. That’s why reducing risks from L. monocytogenes is so important. In any case, if you experience any of the above symptoms, see your doctor or healthcare provider immediately.
Facts
- Pregnant people are about 10 times more likely to get listeriosis than other healthy adults. Because immune systems are altered during pregnancy, it is harder for pregnant people to fight off infections.
- Pregnant Hispanic people are about 24 times more likely to get listeriosis than other healthy adults. This higher incidence may be related to the increased consumption of foods highly susceptible to L. monocytogenes contamination, like queso fresco-type cheeses.
- An estimated 1 in 6 of all L. monocytogenes cases occur in pregnant people. (Centers for Disease Control and Prevention)
"How could listeriosis affect my baby?"
Listeriosis can lead to miscarriage, premature labor, the delivery of a low-birth-weight infant, or infant death. Late-term fetuses who have an infection may develop a wide range of health problems, including intellectual disability, paralysis, seizures, blindness, or impairments of the brain, heart, or kidney. In newborns, L. monocytogenes can cause blood infections and meningitis.
"How can I prevent listeriosis?"
The good news is that listeriosis can be prevented! Here's how...
Time to Chill
- Keep your refrigerator at 40° F (4° C) or colder and the freezer at 0° F (-18° C). Place a thermometer in the refrigerator and check the temperature periodically. It’s normal for the refrigerator to get slightly warmer while defrosting.
- Follow the two-hour rule: Never allow meat, poultry, seafood, produce, dairy, or other foods that require refrigeration to sit at room temperature for more than two hours—one hour if the air temperature is above 90° F (32° C). This also applies to leftovers and take-out foods.
- Use ready-to-eat foods, such as dairy, meat, poultry, seafood, and produce, as soon as possible. The longer they’re stored in the refrigerator, the higher the chance that L. monocytogenes can grow, especially if the refrigerator temperature is above 40° F (4° C).
Fridge TIPS
- Clean your refrigerator regularly.
- Wipe up spills immediately.
- Clean the inside walls and shelves with hot water and a mild liquid dishwashing detergent; then rinse.
- Once a week, check your refrigerator for foods that may be past their expiration date and show signs of spoilage. Spoiled foods will develop an off odor, flavor or texture due to naturally occurring spoilage bacteria. If a food has developed such spoilage characteristics, it should not be eaten.
Refrigerator & Freezer Storage Chart (PDF).
To Eat or Not to Eat?
Avoid:
- Hot dogs, deli meats, and luncheon meats - unless they're reheated until steaming hot.
- Unpasteurized (raw) milk or foods that contain unpasteurized milk.
- Cheeses made with unpasteurized (raw) milk.
- Queso fresco-type cheeses, like queso fresco, queso blanco, and requesón, made from either pasteurized or unpasteurized milk. For more information about queso fresco-type cheeses, visit the queso fresco-type cheeses consumer guidance web page.
- Refrigerated pâtés or meat spreads.
- Refrigerated smoked seafood - unless it's in a cooked dish, such as a casserole.
- Refrigerated smoked seafood, such as salmon, trout, whitefish, cod, tuna, or mackerel, is most often labeled as "nova-style," "lox," "kippered," "smoked," or "jerky." These types of fish are found in the refrigerator section or sold at deli counters of grocery stores and delicatessens.
It's okay to eat:
- Canned or shelf-stable pâtés and meat spreads.
- Canned or shelf-stable smoked seafood.
- Pasteurized milk and foods that contain pasteurized milk.
- Cheeses made with pasteurized milk – except for queso fresco-type cheeses made with pasteurized milk.
Note: See your doctor or healthcare provider if you have questions about listeriosis.