Public Health Division This fact sheet provides basic information only. It must not take the place of medical advice, diagnosis or treatment. Always talk to a health care professional about any health concerns you have, and before you make any changes to your diet, lifestyle or treatment. Listeria August 2008 © Queen's Printer for Ontario What is Listeria?
Listeria monocytogenes (commonly known as listeria) is a bacterium that is widespread in the environment. It is found in soil, vegetation, water, sewage and the feces of animals and humans. Listeria can cause Listeriosis, a serious but rare illness that in certain cases can lead to brain infection and even death. The elderly, newborns, pregnant women and those who have a weakened immune system are most susceptible to developing Listeriosis.
What causes Listeriosis?
Listeriosis is caused by eating food contaminated with Listeria bacteria. Listeria can be found in unpasturized (raw) dairy products, raw vegetables and uncooked meats. Foods can also be contaminated after processing, such as hot dogs, cold cuts or deli meats. Unlike most other harmful bacteria, Listeria will grow on foods stored in a refrigerator. Foods that are contaminated with Listeria look, smell and taste normal. Listeria can be killed by proper cooking procedures. Listeria bacteria are not commonly passed from person to person.
What are the symptoms of Listeriosis?
Symptoms may start suddenly and include: vomiting, nausea, cramps, diarrhea, severe headache, constipation or fever. Some infections become severe and develop into an infection of the brain or the lining of the brain and blood poisoning. Some people experience only mild flu-like symptoms.
What are the symptoms of Listeriosis in newborn babies?
In newborn babies, symptoms may include loss of appetite, lethargy, jaundice, vomiting, skin rash and difficulty breathing.
When do symptoms begin to occur?
Symptoms can occur from three to 70 days after eating foods contaminated with Listeria, with an average incubation period of three weeks.
How likely is it that someone will develop Listeriosis?
Many people may be carriers of Listeria, but few will actually develop Listeriosis. How ill someone becomes depends upon their general state of health, their age and whether they are pregnant. Those who do develop Listeriosis will likely become ill from eating food contaminated with the bacteria, often with
symptoms of what people would call food poisoning. Listeriosis is a relatively rare disease in Canada. Animals and humans can carry the bacterium without knowing it.
How does one test for Listeriosis?
For a list of Recalls go to http://www.inspection.gc.ca/english/fssa/concen/2008listeriae.shtml
