Listeria infections (known as listeriosis) are rare. When they do happen, they usually affect pregnant women in their last trimester, newborns, and people whose immunity is weakened by diseases such as cancer or HIV. People who have had various types of transplants are also more at risk for listeria infection.
Listeria infections are caused by the bacterium Listeria monocytogenes, which can spread through soil and water. A person also can ingest these bacteria by eating certain foods, such as deli meats and cold cuts, soft-ripened cheese, milk, undercooked chicken, uncooked hot dogs, shellfish, and coleslaw made from contaminated cabbage. Many cases of infection, though, don't have an identifiable source.
Infections caused by Listeria include gastroenteritis (vomiting and diarrhea, also called the "stomach flu"), bacteremia (bacterial infection in the blood), meningitis, pneumonia, osteomyelitis (infection in the bone), and endocarditis.
Listeria infections may cause symptoms such as fever, vomiting, diarrhea, lethargy, difficulty breathing, and poor feeding. Pregnant women who develop listeriosis may only have mild flu-like symptoms, but they are at risk for premature delivery, miscarriage, and stillbirth.
People who have weakened immune systems are at particular risk for developing the more serious illnesses from listeriosis, including pneumonia, meningitis, and sepsis.
Fortunately, cases of listeriosis are relatively uncommon. The earlier listeriosis is detected and treated, the better, since it can cause serious and life-threatening infection. And particularly if you are pregnant or in one of the other high-risk groups, avoiding certain foods and drinks can reduce your risk of getting this infection.
Listeriosis is usually treated with antibiotics in the hospital through an intravenous catheter (IV) through a vein. Treatment lasts for about 10 days, but that can vary depending on the body's ability to fight off the infection.
Children whose immune systems are compromised by illness or infection, such as cancer or HIV, are more likely to develop severe listeriosis infections and may need further treatment.
In healthy people with gastroenteritis due to Listeria, symptoms often last only 2 days and they recover completely.
There are no vaccines against the bacteria that cause listeriosis. But you can help protect your family with these food safety precautions:
Always cook food (especially meat and eggs) thoroughly to the proper internal temperature.
Only drink pasteurized milk, and make sure that milk is refrigerated at the appropriate temperature, which is below 40°F (4°C).
Avoid foods made from unpasteurized milk.
If you're in a high-risk group, avoid soft cheeses such as feta, Brie, Camembert, blue-veined cheeses, and Mexican-style cheeses (like queso fresco).
Reheat precooked, prepackaged foods — such as deli meats or hot dogs — to steaming hot temperatures, especially if you're pregnant.
Carefully wash hands and utensils after handling raw foods.
When to Call the Doctor
Call your doctor immediately if your child develops rapid or labored breathing, a fever, poor feeding, vomiting, dehydration, a high-pitched cry, lethargy (excessive sleepiness), or irritability. If your child has listeriosis, the doctor can rule out any other illnesses and start treatment.