[Pathophysiology and epidemiology of listeriosis].

Listeriosis is a severe infectious disease occurring both in humans and in most other animal species. It is caused by a Gram-positive bacterium, Listeria monocytogenes. This facultative intracellular pathogen is widespread in nature and infects humans through contaminated food. After ingestion, bacteria can cross the gut mucosa and disseminate via the bloodstream. They may then invade the central nervous system and the placenta, causing severe meningoencephalitis and fetoplacental infections, respectively. The mortality rate is about 30%, despite antibiotic therapy. Listeriosis offers an excellent model for studying how bacterial pathogens can cross the blood-brain barrier and placenta. Our understanding of the molecular mechanisms of intracellular parasitism and dissemination to host tissues is better for L. monocytogenes than for any other bacterial pathogen.