Human Listeriosis Outbreaks Linked to Dairy Products in Europe

Abstract

Abstract Dairy products have been associated with approximately half of the reported listeriosis outbreaks in Europe. The listeriosis outbreaks have mostly been linked to consumption of raw milk or products made of unpasteurized milk. Outbreaks, such as in Switzerland in 1983 to 1987 caused by unpasteurized soft cheese, in Austria in 1986 by unpasteurized milk, and in France in 1995 by a Brie-type cheese made of unpasteurized milk demonstrate the risks involved in the consumption of raw milk or soft cheeses made of unpasteurized milk. The pasteurization of raw milk, which destroys Listeria monocytogenes , does not eliminate later risk of L. monocytogenes contamination in dairy products. The outbreak in Finland from 1998 to 1999, with butter as the source, shows that dairy products made of pasteurized milk may become contaminated in subsequent stages of production with L. monocytogenes . Extensive work has been ongoing in several European countries during the last decade to prevent outbreaks and decrease the incidence of listeriosis. This work has included preventive measures in food processing plants, consumer education, and early detection of outbreaks. A marked reduction has occurred in the incidence of listeriosis in some of these countries during the 1990s, suggesting a relationship between preventive measures and reduction in listeriosis.