Listeria: What You Need to Know
Listeria monocytogenes is one of the most dangerous foodborne pathogens, causing severe illness and death in vulnerable populations.
What is Listeria?
Listeria monocytogenes is a bacteria that causes listeriosis, a serious infection. Unlike most bacteria, Listeria can grow and multiply at refrigerator temperatures (40°F or below), making it particularly dangerous in ready-to-eat foods.
Listeriosis is the third leading cause of death from foodborne illness in the United States. The CDC estimates that approximately 1,600 people get listeriosis each year, and about 260 die from the infection.
Common Sources of Listeria
Listeria is most commonly found in:
- Deli meats and hot dogs - especially if not reheated to steaming
- Unpasteurized dairy products - soft cheeses, raw milk
- Soft cheeses - brie, camembert, feta, queso fresco
- Smoked seafood - refrigerated smoked fish, lox
- Raw sprouts - alfalfa, clover, radish sprouts
- Cut melons - cantaloupe, honeydew, watermelon
- Refrigerated pâtés or meat spreads
- Pre-packaged salads - especially those containing leafy greens
Who is at Highest Risk?
While anyone can get listeriosis, certain groups are at much higher risk for severe illness:
Pregnant Women
10 times more likely to get listeriosis. Can cause miscarriage, stillbirth, premature delivery, or life-threatening infection in newborns.
Newborns
Can acquire infection from mother during pregnancy or birth, leading to serious health complications.
Adults 65+
Weakened immune systems make older adults 4 times more likely to get infected and have severe outcomes.
Immunocompromised
People with cancer, diabetes, HIV/AIDS, kidney disease, or those taking immunosuppressive medications.
Symptoms of Listeriosis
Symptoms can appear anywhere from 1 to 4 weeks after eating contaminated food, though some cases have reported symptoms within 24 hours or up to 70 days later.
Mild (Invasive)
- Fever and flu-like symptoms
- Muscle aches
- Fatigue
- Nausea and diarrhea
Severe (Invasive)
- Severe headache
- Stiff neck
- Confusion or changes in alertness
- Loss of balance
- Convulsions
In pregnant women: Symptoms are often mild flu-like illness, but the infection can lead to serious complications for the baby, including miscarriage, stillbirth, or severe infection in newborns.
How to Protect Yourself
Keep Your Refrigerator at 40°F or Below
While Listeria can grow at cold temperatures, colder temps slow its growth. Use a refrigerator thermometer to monitor.
Heat Deli Meats and Hot Dogs
Heat these foods to 165°F (steaming hot) before eating, especially if you're pregnant or in a high-risk group.
Avoid High-Risk Foods
If you're in a high-risk group, avoid soft cheeses, unpasteurized dairy, refrigerated smoked seafood, and raw sprouts.
Clean Your Refrigerator Regularly
Listeria can survive in the refrigerator and spread to other foods. Clean spills immediately and sanitize regularly.
Eat Perishable Foods Quickly
Don't store opened packages of hot dogs for more than a week. Eat deli meats within 3-5 days of opening.
What to Do If You've Been Exposed
- Don't panic. Not everyone who eats contaminated food will become sick.
- Watch for symptoms for up to 70 days after exposure.
- Contact your doctor if you develop fever, muscle aches, or other symptoms, especially if you're pregnant or in a high-risk group.
- Seek immediate medical attention if you experience severe headache, stiff neck, confusion, or loss of balance.
- Mention the exposure to your healthcare provider so they can test for listeriosis.