The listeria bacteria can be found in, for example, unpasteurized milk products, raw meat, raw fish and in the soil. It is also found in the intestines of many animals and can be transmitted to humans through close contact.
Outbreaks of listeria can occur every few years. The cause of the outbreaks can usually be traced to food from a certain producer.
For the vast majority, a listeria infection is mild, but for some people the disease can become serious.
Those who become ill may have a fever and flu-like symptoms. In severe cases, an infection can lead to meningitis or blood poisoning.
Source: 1177