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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. Symptoms can occur from 3 to 70 days after eating foods contaminated with Listeria.
Many people may be carriers of Listeria, but few will actually develop Listeriosis. 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?
A blood or spinal fluid test will determine if you have Listeriosis. Contact your health care provider if you have symptoms, especially severe symptoms.
Who is at risk?
How can I reduce the risk of Listeriosis infection?
The following is a guide to reduce the risk of Listeria bacteria for persons at high risk such as pregnant women, the elderly or those who have a weakened immune system.
Foods to Avoid
|Hot dogs, especially straight from the package without further heating.
The fluid within hot dog packages may contain more Listeria than the hot
Avoid spreading fluid from packages onto other foods, cutting boards, utensils, dishes and food preparation surfaces. Wash your hands after handling hot dogs.
|Reheat hot dogs until steaming hot.|
|Deli-meats||Reheat deli-meats until steaming hot. Or try dried and salted deli-meats such as salami and pepperoni, as they generally do not support the growth of Listeria.|
|Soft and semi-soft cheeses such as feta, brie, camembert and blue-veined cheese if they are made from unpasteurized milk||Choose pasteurized milk and milk products including cheeses made from pasteurized milk.|
|Refrigerated pâté and meat spreads||Eat canned or shelf-stable pâté and meat spreads.|
|Refrigerated smoked seafood and fish||Cook refrigerated smoked seafood and fish or eat canned or shelf-stable varieties.|
|Raw or undercooked meat, poultry and fish||Thoroughly cook meat, poultry and fish.|
How is Listeriosis treated?
Listeriosis is treated with antibiotics. Depending on the form of the disease, treatment may take up to six weeks or more. Antibiotics given to pregnant women with Listeriosis can often reduce the risk of infection in the newborn or the unborn child. There is no vaccine to prevent Listeriosis.
What should I do if I have food recalled because of Listeria contamination?
Throw out food that has been recalled because of Listeria contamination. If
you have eaten a contaminated product and do not have any symptoms, no tests
are required. However, if you become ill with fever or serious illness, contact
your health care provider and mention your possible exposure.
Click Here to view the Canadian Food Inspection Agency's (CFIA) most current list of food recalls
For more information contact:
Health Protection Department
(519) 631-9900, ext 225