Listeria: Frequently Asked Questions
"What is Listeria monocytogenes?"
It's a harmful bacterium that can be found in refrigerated, ready-to-eat foods (meat, poultry, seafood, and dairy - unpasteurized milk and milk products or foods made with unpasteurized milk), and produce harvested from soil contaminated with L. monocytogenes. Many animals can carry this bacterium without appearing ill, and thus, it can be found in foods made from animals. L. monocytogenes is unusual because it can grow at refrigerator temperatures where most other foodborne bacteria do not. When eaten, it may cause listeriosis, an illness to which pregnant women and their unborn children are very susceptible.
"How could I get listeriosis?"
By eating ready-to-eat meats, poultry, seafood, and dairy products that are contaminated with L. monocytogenes. You can also get listeriosis by eating contaminated foods processed or packaged in unsanitary conditions or by eating fruits and vegetables that are contaminated from the soil or from manure used as fertilizer.
"How could listeriosis affect me?"
The symptoms can take a few days or even weeks to appear and may include fever, chills, muscle aches, diarrhea or upset stomach, headache, stiff neck, confusion, and loss of balance. In more serious cases, listeriosis could also lead to the mother's death.
Most of the time, pregnant women who are infected with listeriosis don't feel sick. However, they can pass the infection to their unborn babies without even knowing it. That's why prevention of listeriosis is very important. In any case, if you experience any of the above symptoms, see your doctor or healthcare provider immediately.
- Pregnant women are about 10 times more likely to get listeriosis than other healthy adults.
- An estimated 1/6 of all Listeria cases occur in pregnant women.
(Centers for Disease Control and Prevention)
"How could listeriosis affect my baby?"
During the first trimester of pregnancy, listeriosis may cause miscarriage. As the pregnancy progresses to third trimester, the mother is more at risk. Listeriosis can also lead to premature labor, the delivery of a low-birth-weight infant, or infant death. Fetuses who have a late 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.
Listeriosis & Pregnant Hispanic Women
Studies show that pregnant Hispanic women may have a higher incidence of listeriosis than pregnant non-Hispanic women. This is most likely because they might make and eat homemade soft cheese and other traditional foods made from unpasteurized milk. "Queso fresco"- a traditional homemade cheese, prepared from unpasteurized milk and widely consumed by Hispanics - has led to miscarriages, death of newborns, and premature delivery caused by L. monocytogenes.
To prevent the risk of listeriosis, Hispanic pregnant women should not eat homemade soft cheeses and other traditional foods made from unpasteurized milk. Like all other pregnant women, they should follow the food safety precautions outlined below.
"How can I prevent listeriosis?"
The good news is that listeriosis can be prevented! Here's how...
Time to Chill
- Your refrigerator should register at 40° F (4° C) or below and the freezer at 0° F (-18° C). Place a refrigerator thermometer in the refrigerator, and check the temperature periodically. During the automatic defrost cycle, the temperature may temporarily register slightly higher than 40° F. This is okay.
- Refrigerate or freeze perishables, prepared food, and leftovers within two hours of eating or preparation. Follow the 2-Hour Rule: Discard food that's left out at room temperature for longer than 2 hours. When temperatures are above 90° F (32° C), discard food after 1 hour.
- Use ready-to-eat, perishable foods, such as dairy, meat, poultry, seafood, and produce, as soon as possible.
- 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 expiration and "use by" dates, and throw out foods if the date has passed. Follow the recommended storage times for foods.
To Eat or Not to Eat?
- Hot dogs, deli meats, and luncheon meats - unless they're reheated until steaming hot.
- Soft cheeses like Feta, Brie, and Camembert, "blue-veined cheeses," or "queso blanco," "queso fresco," or Panela - unless they're made with pasteurized milk. Make sure the label says, "made with pasteurized milk."
- 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.)
- Raw (unpasteurized) milk or foods that contain unpasteurized milk.
It's okay to eat:
- Canned or shelf-stable (able to be stored unrefrigerated on the shelf) pâtés and meat spreads.
- Canned or shelf-stable smoked seafood.
- Pasteurized milk or foods that contain pasteurized milk.
Note: See your doctor or healthcare provider if you have questions about listeriosis.