Listeria monocytogenes is a pathogenic bacterium which is dangerous for certain groups of individuals including small children, immunodeficient people and pregnant women, owing to the fact that it causes listeriosis.

Listeria infections can cause spontaneous abortions (miscarriages) and stillbirths among pregnant women, as well as some other disorders. The bacterium, which can grow at low temperatures (refrigeration) is a potential hazard in products that are stored for a long time at low temperatures and/or not heated prior to consumption.

Pregnant women thus should avoid soft cheeses made from raw milk as well as raw or low-temperature smoked fish (sushi, smoked salmon).

Hard cheeses are made with heated milk and are too salty; these products are less likely to be contaminated with Listeria , thus do not pose a risk for listeriosis.

Listeria is heat sensitive and will die at temperatures above 75 degrees Celsius. If a meal with raw-milk soft cheeses is heated above 80 degrees Celsius, there will be no health risk from Listeria. Any meal which is thoroughly cooked (100 degrees) can be considered safe from Listeria infection.