Listeria monocytogenes is a kind of bacteria often found in soil and water, which can cause serious illness.
Bacteria are too small to be seen without a microscope.
Illness from eating foods with Listeria monocytogenes is called listeriosis. Most people do not get listeriosis. However, pregnant women and newborns, older adults, and people with weakened immune systems caused by cancer treatments, AIDS, diabetes, kidney disease, etc., are at risk for becoming seriously ill from eating foods that contain Listeria monocytogenes. Listeriosis has flu-like symptoms, such as fever and chills. Sometimes people have an upset stomach, but not always.