Updated: May 21, 2026
What is Listeriosis?
Listeriosis is a serious infection caused by eating food contaminated with the bacterium Listeria monocytogenes. It has recently been recognized as an important public health concern in the United States. The disease affects primarily pregnant women, newborns, adults aged 65 or older, and people with weakened immune systems. Healthy adults and children may occasionally get infected with Listeria, but they rarely become seriously ill.
Listeriosis is the third leading cause of death from foodborne illness in the United States. In the US, it is estimated that 1,600 persons become ill with listeriosis each year, and about 260 people die. South Carolina reports an average of 14 cases annually. The risk of an individual person developing Listeria infection after consumption of a contaminated product is very small. If you have eaten a potentially contaminated product (food that has been recalled or linked to an outbreak) and have a fever and other symptoms of listeriosis, please contact a health care provider and inform them of your exposure. However, if you have eaten a potentially contaminated product and do not feel sick, most experts agree that you do not need tests or treatment. It is recommended that you consult with a health care provider if you have questions about what to do.
What are the symptoms?
There are two kinds of illness Listeria can cause: intestinal illness and invasive illness.
- Intestinal illness is rarely diagnosed because laboratories do not regularly test patient samples for Listeria. Symptoms of intestinal illness usually start within 24 hours after eating food contaminated with Listeria and usually last 1 to 3 days. Symptoms include both diarrhea and vomiting. Symptoms are usually mild; however, some people with intestinal illness may develop invasive illness.
- Invasive illness means that the bacteria have spread beyond the intestines (gut). Symptoms of invasive illness usually start within 2 weeks after eating food contaminated with Listeria.
Symptoms of invasive illness
- For women who are pregnant, symptoms typically include: fever and flu-like symptoms (such as muscle aches and fatigue). Infection during pregnancy can lead to miscarriage, stillbirth, premature delivery, or life-threatening infection of the newborn.
- For other people, symptoms typically include: fever, flu-like symptoms (such as muscle aches and fatigue), headache, stiff neck, confusion, loss of balance, and seizures. In cases of invasive listeriosis not associated with pregnancy, almost 1 in 6 people die.
How is listeriosis treated?
Most people infected with the bacteria do not require any treatment other than supportive care (rest and lots of fluids). Most people recover from an intestinal illness without antibiotic treatment, but antibiotics may be used for patients who are very ill or at risk of becoming very ill. In contrast, individuals with an invasive illness need to be treated with antibiotics.
How do people catch this disease?
You can get listeriosis by eating food contaminated with Listeria. The bacteria is found in soil and water. Vegetables can become contaminated from the soil or from manure used as fertilizer. Animals can carry the bacterium without appearing ill and can contaminate foods of animal origin such as meats and dairy products. The bacteria has been found in a variety of raw foods, such as uncooked meats and vegetables, as well as in processed foods that become contaminated after processing, such as soft cheeses and cold cuts at the deli counter. Unpasteurized (raw) milk or foods made from unpasteurized milk including cheese, ice cream, and yogurt, may contain the bacteria. Some cheeses (such as queso fresco-type cheeses) are more prone to causing Listeria infections than others. This is because certain cheeses are made in a way that allows Listeria germs to contaminate and grow. These fresh, soft cheeses don’t undergo a lengthy aging process (which helps kill Listeria in other cheeses). They are high-moisture, low-acidity cheeses, which provide an environment where Listeria can thrive.
Listeria is killed by pasteurization, and heating procedures used to prepare ready-to-eat processed meats should be sufficient to kill the bacterium; however, unless good manufacturing practices are followed, contamination can occur after processing.
Babies can be born with listeriosis if their mothers eat contaminated food during pregnancy. Although healthy persons may consume contaminated foods without becoming ill, those at increased risk for infection can probably get listeriosis after eating food contaminated with even just a few bacteria.
What can be done to stop the spread of this disease?
Early detection and reporting of outbreaks of listeriosis to local and state health departments can help identify sources of infection and prevent more cases of the disease. Additionally, if you fall into one of the high-risk groups mentioned above, it is recommended that you opt for safer food choices to safeguard your health or pregnancy. Please refer to the table below for potential dietary recommendations.
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