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What is
Listeria?

The bacterium Listeria monocytogenes causes foodborne illness, and can cause high fever, severe headache, neck stiffness and nausea. It is an important public health problem in the United States.

Healthy people rarely contract listeriosis. Listeriosis can cause miscarriages and stillbirths, as well as serious and sometimes fatal infections in those with weaker or compromised immune systems, such as infants, older adults, and persons living with HIV or undergoing chemotherapy.

Listeriosis is an uncommon but potentially fatal infection usually caused by food contamination.

The bacterium Listeria monocytogenes is what causes foodborne illness, and can cause high fever, severe headache, neck stiffness and nausea. It is an important public health problem in the United States.

Healthy people rarely contract listeriosis. Listeriosis can cause miscarriages and stillbirths, as well as serious and sometimes fatal infections in those with weaker or compromised immune systems, such as infants, older adults, and persons living with HIV or undergoing chemotherapy.

What are the symptoms
of Listeriosis?

A person with listeriosis usually has fever and muscle aches, sometimes preceded by diarrhea or other gastrointestinal symptoms. Almost everyone who is diagnosed with listeriosis has “invasive” infection, in which the bacteria spread beyond the gastrointestinal tract.

Symptoms vary
with the infected person

  • Pregnant women typically experience fever and other non-specific symptoms, such as fatigue and aches.
  • Infections during pregnancy can lead to miscarriage, stillbirth, premature delivery, or life-threatening infection of the newborn.
  • Other persons (who aren’t pregnant), in addition to fever and muscle aches, symptoms can also include headache, stiff neck, confusion, loss of balance, and convulsions.


Manifestations of listeriosis are host-dependent. Listeriosis can present in different ways depending on the type of infection. In older adults and immune-compromised persons, septicemia and meningitis are the most common clinical presentations.

Pregnant women may experience a fever and other non-specific symptoms, such as fatigue and aches, followed by fetal loss or bacteremia and meningitis in their newborns. Immuno-competent persons may experience acute febrile gastroenteritis or no symptoms.

In the USA, an estimated 1,600 persons become seriously ill with listeriosis annually.
Of these, 260 die.

How does someone
get Listeriosis?

You get listeriosis by eating food contaminated with Listeria monocytogenes. Babies can be born with listeriosis if their mothers eat contaminated food during pregnancy. However, healthy persons may consume contaminated foods without becoming ill.

Persons at risk can prevent listeriosis by avoiding certain high-risk foods (see below) and by handling and storing food properly.

who gets Listeriosis?

  • Pregnant women: Pregnant women are about 13 times more likely than the general population to get listeriosis. About one in six (17%) cases of listeriosis occurs during pregnancy.
  • Newborn babies: Newborn babies suffer the most serious effects of infection in pregnancy.
  • Persons with weakened immune systems from transplants or certain diseases, therapies, or medications.
  • Persons with cancer, diabetes, alcoholism, liver or kidney disease.
  • Persons with HIV/AIDS: Persons with AIDS are almost 300 times more likely to get listeriosis than people with healthy immune systems.
  • Older adults


Healthy children and adults occasionally may get infected with Listeria, but they rarely become seriously ill.

Transmission of Listeriosis

Most human infections follow consumption of contaminated food. When Listeria bacteria get into a food processing factory, they can live there for years, sometimes contaminating food products.

The bacterium has been found in a variety of raw foods, such as uncooked meats and vegetables, as well as in foods that become contaminated after cooking or processing, such as soft cheeses, processed meats such as hot dogs and deli meat (both products in factory-sealed packages and products sold at deli counters), and smoked seafood. 

Unpasteurized (raw) milk and cheeses and other foods made from unpasteurized milk are particularly likely to contain the bacterium.

Listeria is killed by pasteurization and cooking; however, in some ready-to-eat foods, such as hot dogs and deli meats, contamination may occur after factory cooking but before packaging.

Unlike most bacteria, Listeria can grow and multiply in some foods in the refrigerator.

How do I know
if I have
Listeriosis?

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

How is Listeriosis treated?

  • Listeriosis is treated with antibiotics. A person in a high-risk category who experiences fever and other non-specific symptoms, such as fatigue and aches, within 2 months of eating contaminated food should seek medical care and tell the physician or health care provider about eating the contaminated food.
  • If a person has eaten food contaminated with Listeria and does not have any symptoms, most experts believe that no tests or treatment are needed, even for persons at high risk for listeriosis.
 Outcomes: Even with prompt treatment, some listeriosis cases result in death.
This is particularly likely in older adults and in persons with other serious medical problems.
check out more from the CDC

Recommendations
for persons with a
higher risk
for listeriosis

Older adults, women who are pregnant, and individuals who are immunocompromised, including transplant recipients, individuals with HIV/AIDS, and cancer survivors.

Meats

  • Do not eat hot dogs, luncheon meats, cold cuts, other deli meats (e.g., bologna), or fermented or dry sausages 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 lunch meat packages on other foods, utensils, and food preparation surfaces, and wash hands after handling hot dogs, luncheon meats, and deli meats.
  • Pay attention to labels. 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. Refrigerate after opening.

Cheeses

Do not eat soft cheese such as feta, queso blanco, queso fresco, brie, Camembert, blue-veined, or queso panela unless it is labeled as made with pasteurized milk.

Make sure the label says: MADE WITH PASTEURIZED MILK

Seafood

  • Do not eat refrigerated smoked seafood, unless it is contained in a cooked dish, such as a casserole, or unless it is a canned or shelf-stable product.
  • Refrigerated smoked seafood like salmon, trout, whitefish, cod, tuna, or mackerel, is most often labeled as “nova-style,” “lox,” “kippered,” “smoked,” or “jerky.”
  • These fish are typically found in the refrigerator section or sold at seafood and deli counters of grocery stores and delicatessens.
  • Canned and shelf stable tuna, salmon, and other fish products are safe to eat.

It's All About the Fridge

  • Keeping the refrigerator at 40°F or below is important because – unlike most foodborne bacteria – Listeria will grow in the refrigerator, and it will grow faster at refrigerator temperatures above 40°F.
  • And, the longer ready-to-eat, refrigerated foods are stored in the refrigerator, the more time Listeria has to grow. Finally, Listeria can spread from one food to another through spills in the refrigerator.

3 Easy Steps to Prevention

The FDA, CDC, and USDA recommend that consumers follow these three simple steps to help prevent listeriosis:

  1. Keep the refrigerator at 40°F (4°C) or below.
  2. Use ready-to-eat, refrigerated foods ASAP.
  3. Clean the refrigerator regularly.

If you’re at risk or if you’re preparing food for someone who is ...

read on for specific things you should know.

Three very specific things you can do to help prevent listeriosis. ←

Chill ...

at the Right Temperature
  • 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 fridge, and check the temperature periodically. Adjust the refrigerator temperature control, if necessary. Place a second thermometer in the freezer.

Use ...

Ready-to-Eat Foods ASAP!
  • Use refrigerated, ready-to-eat foods as soon as possible. The longer they’re stored in the refrigerator, the more chance Listeria has to grow.

clean ...

the Refrigerator
  • Clean your refrigerator regularly.
  • Wipe up spills immediately. This is particularly important, so Listeria doesn’t have a place to grow and then spread to other foods.
  • Clean the inside walls and shelves with hot water and a mild liquid dishwashing detergent; then rinse. Then dry with a clean cloth or paper towel.

“It turns out that what could have been a benign lunch in the park on an early fall day was the beginning of my education in foodborne illness and food safety as well as the start of the fight that began her young life.”

Listeria stories