Listeriosis and its transmission by food.

Investigations of recent outbreaks and sporadic cases of listeriosis in North America and other countries have shown that the infection can be foodborne. Pregnant women and their fetuses, the elderly, and immuno-compromised individuals are at increased risk of listeriosis. Listeria monocytogenes, the causative bacterium, is widespread in nature and is found in many foods. It can grow at refrigerator temperatures and is resistant to adverse conditions and to several antibiotics. The generally low levels of the organism found in foods require procedures to optimize their detection and recovery. Occurrence and characteristics of the bacterium, virulence and disease symptoms, transmission to humans, incidence and behavior in foods, and means of controlling growth in foods are reviewed.