What is Listeria infection (listeriosis)?
While anyone can get it, people who are most at risk of becoming very ill or even dying from listeriosis are pregnant women, their unborn babies, older adults, and people who have a weakened immune system. A weakened immune system may be the result of another condition (like AIDS or cancer) or a medication they are taking.
About 1,600 people get listeriosis in the United States each year.
Symptoms and Causes
What are the causes and symptoms of Listeria/listeriosis?
Listeriosis is caused by Listeria monocytogenes, bacteria that is found in soil and water. It can be found in a variety of raw foods as well as in processed foods and foods made from unpasteurized milk. While these are high risk foods, Listeriosis has been associated with virtually every food category when the food is not properly handled and prepared. One thing that makes Listeria different from other foodborne illnesses is that it can grow even in a refrigerator.
- Symptoms of Listeria infection in pregnant women typically are fever and other flu-like symptoms, such as fatigue and muscle aches. However, this can progress quickly to miscarriage, stillbirth, premature delivery or even death of the baby if not treated.
- In people who are not pregnant, symptoms can include vomiting, diarrhea, headache, stiff neck, confusion, loss of balance and convulsions, as well as fever and muscle aches.
- Symptoms typically appear 24 hours to 4 weeks after eating food contaminated with Listeria, but that can range from the same day to up to 70 days later.
Call your healthcare provider if you or your child experiences these symptoms.
Diagnosis and Tests
When should a doctor be called and how is Listeria/listeriosis diagnosed?
Sometimes listeriosis is misdiagnosed, as it can have many of the same symptoms as other conditions. A definite diagnosis requires sending a sample of blood or spinal fluid to a lab for testing.
If you learn that a food you have recently eaten has been recalled due to Listeria infection, especially if you are having any of the symptoms of listeriosis, you should tell your healthcare provider about it right away, so he or she can decide whether to order lab testing.
Management and Treatment
How is Listeria/listeriosis treated?
Some people with mild symptoms of listeriosis might not need to be treated at all. For those who do need to be treated (especially pregnant women), antibiotics are used. Patients may also be given medication to manage symptoms such as nausea and vomiting if needed.
How is Listeria/listeriosis prevented?
Taking care with what you eat and how you store and prepare food, especially during pregnancy, can help reduce your risk of contracting listeriosis. (Pregnant women are 20 times more likely to contract listeriosis than other people.) Here are tips on how you can decrease your chance of contracting listeriosis:
- Avoid hot dogs, luncheon meats and fermented or dry sausages (deli meats) unless they are heated to an internal temperature of 165°F or until steaming hot just before serving.
- Avoid getting fluid from hot dog and lunchmeat packages on other foods, utensils and food preparation surfaces. Wash your hands after handling these types of items.
- Do not eat soft cheese such as feta, queso blanco, queso fresco, brie, Camembert, blue-veined, or panela (queso panela) unless it is clearly labeled as having been made with pasteurized milk.
- Do not eat refrigerated pâté or meat spreads from a deli or meat counter or from the refrigerated section of a store. Foods that do not need refrigeration, like canned or shelf-stable pâté and meat spreads, are safe to eat but they should be refrigerated after opening.
- Avoid sushi, undercooked meats, raw eggs, Caesar dressing, mayonnaise, raw milk and items made with raw milk.
- Wash fresh fruits and vegetables well under running water just before eating, cutting or cooking, even if you plan to peel the produce first. Scrub firm produce such as melons and cucumbers with a clean produce brush.
- Heat up leftovers until they are steaming hot. Don’t eat them at all after several days.
- Keep your refrigerator at 40°F or lower and the freezer at 0° F or lower. While Listeria can still live at these temperatures, it is more difficult.
- Wrap food in plastic wrap or foil, or place it in plastic bags or clean covered containers, before you place them in the refrigerator. Make sure that certain foods such as raw meat do not leak juices onto other foods.
- Clean up all spills in your refrigerator right away — especially juices from hot dog and lunchmeat packages or raw meat or poultry.
- Thoroughly wash food preparation surfaces with warm, soapy water, especially cutting boards.
- Wash dish cloths, towels and cloth grocery bags often, using hot water.
- Wash your hands with warm water and soap for at least 20 seconds before and after handling food.