What is Listeria? What to know about the bacteria that can cause listeriosis

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Tuesday, January 29, 2019
What to know about listeria
Here's what you should know about Listeria.

What is Listeria? What is listeriosis?

Listeria is a rare but dangerous bacteria according to the Centers for Disease Control.

Listeriosis is a potentially life-threatening infection you can get if you consume food contaminated with the bacteria.

How common is listeriosis?

About 1,600 people get listeriosis in the United States every year. Some groups are more susceptible than others.

How dangerous is Listeria?

About 1 in 5 people who develop an invasive Listeria infection die, according to the CDC. An invasive infection means the bacteria has spread beyond the gut.

Adults 65 and older and people with weakened immune systems: Listeria infections can be serious for these groups and can lead to sepsis or meningitis.

Newborns: Listeria infection can be serious in newborns, causing death in about 3% of cases.

Pregnant women: Though the illness is usually mild in the mother, Listeria infection is a serious concern for the unborn baby. Listeriosis can cause miscarriage, stillbirth, or newborn death, leading to loss of fetus in about 20% of cases.

All others: People who are not in the vulnerable groups listed above do not typically get sick from Listeria infections.

Which foods can get contaminated?

These foods are the most likely to cause infection, according to the CDC.

Queso fresco and other soft cheeses

Raw sprouts


Hot dogs, pates, lunch meats, and cold cuts

Smoked seafood

Raw (unpasteurized) milk

Listeria infection symptoms

The symptoms of invasive Listeria infections differ depending on whether the patient is pregnant.

Pregnant women: Pregnant women may experience fever, fatigue and muscle aches. Though the infection is relatively mild, you should seek medical attention due to the risk for the baby.

People other than pregnant women: In addition to the flu-like symptoms experienced by pregnant women, other patients may experience a headache, stiff neck, confusion, loss of balance and convulsions.

How to prevent Listeria infection

Everyone should follow these tips to lower the risk of infection:

  • Do not consume raw (unpasteurized) milk. Check the labels of milk products, such as cheese, to make sure it has been pasteurized.
  • Make sure your refrigerator is cold enough. Cut melon should be stored at 41 degrees Fahrenheit or colder, and milk products should be stored at 40 degrees Fahrenheit or colder.
  • Do not eat cut melon that has been sitting at room temperature for more than four hours. Even if it's properly stored in the refrigerator, throw it in the trash or compost after one week.
  • Be careful with the juices from hot dogs, pates, lunch meats, and cold cuts. Make sure they don't get onto foods and utensils, and be sure to thoroughly clean food preparation surfaces.
  • Throw out hot dogs after one week if opened, two weeks if unopened. Throw out lunch and deli meat after 3-5 days if opened, two weeks if unopened.

Vulnerable groups (pregnant women, people 65 and older and people with weakened immune systems) should follow these extra tips:

  • Be extra careful with soft cheeses, such as brie and queso. Make absolutely sure it was made with pasteurized milk.
  • Do not eat anything pre-packaged or from a restaurant that contains sprouts. When preparing your own sprouts, make sure they are thoroughly cooked.
  • Be extra careful with seafood. It is OK to eat if it can be safely stored at room temperature (such as regular canned tuna). If it must be refrigerated, only eat it as part of a cooked dish.
  • Do not eat pate or other refrigerated meat spreads. If eating hot dogs or deli meats, make sure the internal temperature has reached 165 degrees Fahrenheit during cooking.

What should I do if I ate contaminated food?

If you ate food that has been recalled (or has otherwise caused Listeria concerns) within the past two months and you feel sick, seek medical care. This is especially important if you are in the vulnerable groups listed above.

If you do not feel sick, most experts believe you don't need to do anything except throw the contaminated food out.


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