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What is Listeria?

July 07, 2023 by FreshByte Software

Listeria outbreak fears are in the news again this summer with frozen fruit recalls at Walmart, Whole Foods, Trader Joe’s, Target, Aldi, and AWG.

“SunOpta Inc’s subsidiary, Sunrise Growers Inc., has issued a voluntary recall of specific frozen fruit products linked to pineapple provided by a third-party supplier due to the potential for these products to be contaminated with Listeria monocytogenes,” the FDA said on June 21, 2023.

Listeria monocytogenes is an organism that can cause serious and sometimes fatal infections in young children, frail or elderly people, and others with weakened immune systems.

Listeria Can Lead to Illness, Hospitalizations, and Death

Although healthy individuals may suffer only short-term symptoms such as high fever, severe headache, stiffness, nausea, abdominal pain, and diarrhea, listeria infection can cause miscarriages and stillbirths among pregnant women. Any consumers concerned about an illness should contact a physician.

“Listeria infection is a foodborne bacterial illness that can be very serious for pregnant women, people older than 65, and people with weakened immune systems,” says the Mayo Clinic. “Healthy people rarely become ill from listeria infection, but the disease can be fatal to unborn babies, newborns, and people with weakened immune systems. Prompt antibiotic treatment can help curb the effects of listeria infection.”

Listeria is commonly caused by eating improperly processed deli meats and unpasteurized milk products – such as the Cricket Creek Farm cheese recall this summer – but the bacteria can survive refrigeration and even freezing.

Multistate Listeria Outbreaks in the Last Six Months

The CDC has reported on four multistate Listeria outbreaks in the last six months that have sickened people, as well as resulted in pregnancy loss and death:

  • Listeria Outbreak Linked to Leafy Greens: 19 people became ill across 16 states with 18 requiring hospitalizations in an outbreak where sick people samples were collected from July 3, 2018, to March 31, 2023.

  • Listeria Outbreak Linked to Enoki Mushrooms: Many samples of enoki mushrooms that were tested in this outbreak (October 2022 to February 2023) were contaminated with Listeria, some of which had large amounts of Listeria. 5 people were hospitalized across 4 states.

  • Listeria Outbreak Linked to Deli Meat and Cheese: Deli meats (cold cuts, lunch meats, hot dogs, and pates) and deli-sliced cheeses are known sources of Listeria illnesses. This outbreak (April 2021 to October 2022) across six states resulted in 16 illnesses across 6 states with 13 hospitalizations. One person got sick during their pregnancy, resulting in pregnancy loss, and one death was reported in Maryland.

  • Listeria Outbreak Linked to Brie and Camembert Cheese: 6 people were sickened across 6 states with 5 hospitalizations.

Listeria (Listeriosis): A Serious Infection

The CDC says here is everything you need to know about listeriosis, a serious infection caused by the germ Listeria monocytogenes.

“People usually become ill with listeriosis after eating contaminated food. The disease primarily affects pregnant women, newborns, older adults, and people with weakened immune systems. It’s rare for people in other groups to get sick with Listeria infection,” explains the CDC.

For some, the infection can be quite serious, even deadly.

“Listeriosis is usually a mild illness for pregnant women, but it causes severe disease in the fetus or newborn baby,” said the CDC. “Some people with Listeria infections, most commonly adults 65 years and older and people with weakened immune systems develop severe infections of the bloodstream (causing sepsis) or brain (causing meningitis or encephalitis). Listeria infections can sometimes affect other parts of the body, including bones, joints, and sites in the chest and abdomen.”

Listeria: Questions and Answers

The CDC “Questions and Answers” on Listeria include:

  • What are the Symptoms of Listeriosis? Listeriosis can cause a variety of symptoms, depending on the person and the part of the body affected. Listeria can cause fever and diarrhea like other foodborne germs, but this type of Listeria infection is rarely diagnosed. Symptoms in people with invasive listeriosis, meaning the bacteria has spread beyond the gut, depend on whether the person is pregnant.

o   Pregnant women: Pregnant women typically experience only fever and other flu-like symptoms, such as fatigue and muscle aches. However, infections during pregnancy can lead to miscarriage, stillbirth, premature delivery, or life-threatening infection of the newborn.

o   People other than pregnant women: Symptoms can include headache, stiff neck, confusion, loss of balance, and convulsions in addition to fever and muscle aches.

People with invasive listeriosis usually report symptoms starting 1 to 4 weeks after eating food contaminated with Listeria; some people have reported symptoms starting as late as 70 days after exposure or as early as the same day of exposure.

  • How is Listeriosis Diagnosed and Treated? Listeriosis is usually diagnosed when a bacterial culture (a type of laboratory test) grows Listeria monocytogenes from body tissue or fluid, such as blood, spinal fluid, or the placenta. Listeriosis is treated with antibiotics.

  • How Do People Get Infected with Listeria? Listeriosis is usually caused by eating food contaminated with Listeria monocytogenes. If infection occurs during pregnancy, Listeria bacteria can spread through the placenta.

  • What Should I Do If I Ate Food that May Have Been Contaminated with Listeria? You should seek medical care and tell the doctor about eating possibly contaminated food if you have a fever and other symptoms of possible listeriosis, such as fatigue and muscle aches, within two months of eating possibly contaminated food. This is especially important if you are pregnant, aged 65 or older, or have a weakened immune system. If you eat food possibly contaminated with Listeria and do not feel sick, most experts believe you do not need tests or treatment. Talk with your medical provider if you have questions about what to do after eating possibly contaminated food.

  • Is Listeriosis a Serious Disease? Most people with invasive listeriosis require hospital care, and about one in five people with the infection die. When listeriosis occurs during pregnancy, it can cause miscarriage, stillbirth, or newborn death. Listeriosis during pregnancy results in fetal loss in about 20 percent and newborn death in about 3 percent of cases.

  • How Many People Get Listeriosis Each Year? Every year, about 1,600 people get listeriosis in the United States.

  • Are Outbreaks of Listeriosis Common? A few outbreaks of listeriosis are identified most years. Even though most cases of listeriosis are not part of recognized outbreaks, outbreak investigations help show which foods are sources of listeriosis.

  • What are Public Health Agencies Doing to Prevent or Control Listeriosis? Federal, state, and local governments are doing the following:

o   Providing guidance to industry and developing and enforcing regulations, like the Food Safety Modernization Act, to focus food safety efforts on safer production and handling of foods.


o   Tracking Listeria infections to identify opportunities to improve policies and practices, particularly to protect groups of people who are more likely to get sick with listeriosis.


o   Investigating and stopping outbreaks by recalling contaminated foods and warning the public.


o   Applying CDC’s enhanced approach to investigating Listeria infections in all states so disease detectives can rapidly solve outbreaks by:

    1.  DNA fingerprinting the germ to identify outbreaks and contaminated foods, and interviewing people who are sick – quickly and with the same questions – about what they ate.

    2. Helping health departments get the technology and training for whole genome sequencing and analysis, which will make it possible to find Listeria infections and outbreaks more quickly and track them to their sources.
  • How Can I Help Protect Myself and My Family from Infection? People who are more likely to get a Listeria infection (pregnant women, people 65 years or older, and people with a weakened immune system) and those who prepare food for them can:

o   Know which foods are risky and avoid these foods.

o   Avoid drinking raw (unpasteurized) milk or eating soft cheeses made from it.

o   Be aware that Mexican-style cheeses made from pasteurized milk, such as queso fresco, have caused Listeria infections, likely because they were contaminated during cheese-making.

o   Heat deli meats and hot dogs until steaming hot before eating.

o   Refrigerate leftovers within 2 hours in shallow, covered containers and use within 3-4 days.

o   Avoid cross-contamination in the refrigerator or other places in the kitchen.

o   Use a thermometer to make sure your refrigerator is 40°F or lower and your freezer is 0°F or lower.



Tags: Safety, Food Recalls

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