Occurrence: almost all raw food, has been found in milk and milk products, meat and meat products, vegetables, fish, shellfish and polluted water.

Incubation period: one day up to several weeks.

Symptoms:  Healthy people usually do not get sick but there are risk groups such as pregnant women, children and people with weak immune systems. Some suffer from flu-like symptoms and fetuses can become infected, which can cause a miscarriage. Others suffer from meningitis or brain inflammation. Approximately 60-90 people are infected per year in Sweden and this is increasing. The mortality is approx. 30 percent, but an infection leads to lifelong immunity.

Reason for outbreaks: can grow at refrigerator temperature, if stored longer the bacteria can multiply to dangerous levels. It is resistant to changes in its environment and can even grow in a vacuum.

Prevention: choose fresh foods, raw foods should be eaten as soon as possible and be prepared to an internal temperature of at least 70°C.