What Is Listeriosis and Who Has a Higher Risk?

Listeriosis is a rare but serious illness caused by eating food contaminated with the bacteria called Listeria monocytogenes. About 1,600 people in the United States get sick from listeria each year. It is the third leading cause of death from food poisoning.

Babies can be born with listeriosis if their mothers eat contaminated food during pregnancy. The disease primarily affects older adults, pregnant women, newborns and adults with weakened immune systems. Although rare, people without such risk factors also can be affected.

How Does Listeria Get in Our Food and What Foods Are Risky?

Listeria monocytogenes is found in dirt, water and plants. It can be tracked into a manufacturing facility, carried by animals or spread by employees who don’t use proper sanitation practices.

When Listeria bacteria get into a food processing factory, they can live there for years. Unlike most bacteria, Listeria monocytogenes can grow at refrigerator temperatures, as low as 40 degrees Fahrenheit.

Listeria monocytogenes has been found in a variety of foods including sprouts, raw milk, unpasteurized dairy products and ready-to-eat foods such as deli meats, hot dogs and soft cheeses.

Why Listeria Is Challenging?

• When someone eats food contaminated with listeria, sickness or miscarriage may not occur until weeks later when it is difficult to identify which food was the source.
• Listeria can contaminate many foods that we don't usually cook, such as deli meats, cheeses and sprouts.
• Some foods we might not suspect can be contaminated with listeria and cause sickness and outbreaks, such as cantaloupes and celery.
• Listeria are a hardy germs that even can grow on foods that are refrigerated.
• Listeria can hide unnoticed in the equipment or appliances where food is prepared, including in factories and grocery stores.
• Listeria can be killed by cooking and pasteurization. But in some ready-to-eat meats, such as hot dogs and deli meats, contamination may occur after factory cooking but before packaging or even at the deli counter.

How Do I Know if I Have Listeriosis?

If you become very sick with fever and muscle aches or stiff neck, or if you develop fever and chills while pregnant, consult your doctor immediately. A blood or spinal fluid test (to look for the bacteria) will show if you have listeriosis.

What Should I Do To Keep Listeria Out of My Kitchen?

• Consumers are advised by the U.S. Food and Drug Administration to wash fruits and vegetables under running water just before eating, cutting or cooking.
• Scrub firm produce such as melons and cucumbers with a clean produce brush.
• Avoid unpasteurized milk and soft cheeses that are not made with pasteurized milk.
• Keep your refrigerator at 40 degrees F or lower and freezer at 0 degrees F or lower. Keep foods in your refrigerator as cold as possible without causing them to freeze.
• Wrap or cover foods with a sheet of plastic wrap or foil or put foods in plastic bags or clean covered containers before you place them in the refrigerator. Make certain foods do not leak juices onto other foods.
• Clean your refrigerator regularly, especially when there is a spill from hot dog and lunch meat packages, raw meat or raw poultry.
• Wash your hands and clean kitchen surfaces often. This also helps prevent illnesses caused by other foodborne pathogens.

What Should I Do When There Is a Recall Due to Potential Listeria Contamination?

• Do not eat any of the recalled products.
• Check the refrigerator or freezer for any recalled products. Place the products in a closed plastic bag in a sealed trash can to prevent other people or animals from eating them.
• When in doubt, throw it out. Throw recalled products away or return them to the place of purchase, even if some of the product has been eaten and no one has become ill.
• Clean and sanitize the inside walls and shelves of your refrigerator, freezer or any surfaces that had contact with recalled products.
• Wash hands with warm water and soap for at least 20 seconds before and after handling recalled products.

What Should I Do if I Ate Recalled Products?

• If you have eaten a recalled product and do not have any symptoms, most experts believe tests or treatment are not needed, even for people at higher risk for listeriosis.
• Consumers who develop symptoms of listeriosis after eating recalled products should seek medical care and tell a health care provider about eating a product that was recalled because of possible listeria contamination. Although people sometimes can develop listeriosis up to two months after eating contaminated food, symptoms usually start within several days.

References

Centers for Disease Control and Prevention. 2013. Listeria (Listeriosis) Sources. Available from: http://www.cdc.gov/listeria/sources.html.

Centers for Disease Control and Prevention. 2013. Vital Signs. Recipe for Food Safety – Protecting People From Deadly Listeria Food Poisoning. Available from: http://www.cdc.gov/vitalsigns/listeria/.

Centers for Disease Control and Prevention. 2015. Multistate Outbreak of Listeriosis Linked to Blue Bell Creameries Products. Available from: http://www.cdc.gov/listeria/outbreaks/ice-cream-03-15/advice-consumers.html.

Tompkin, R.B. 2002. Control of Listeria monocytogenes in the Food-processing Environment. Journal of Food Protection 65(4):709-725.

U.S. Food and Drug Administration. 2015. FDA Investigates Listeria monocytogenes in Ice Cream Products from Blue Bell Creameries. Available from: http://www.fda.gov/Food/RecallsOutbreaksEmergencies/Outbreaks/ucm438104.htm.

U.S. Food and Drug Administration. 2015. Keep Listeria Out of Your Kitchen. Available from: http://www.fda.gov/ForConsumers/ConsumerUpdates/ucm274114.htm.