Listeriosis is a bacterial infection caused by Listeria monocytogenes. While many bacteria generally infect specific locations within the human body, listeria may infect many different sites, such as the brain or spinal cord membranes, or the bloodstream. Anyone can get the disease, but those at highest risk are newborns, the elderly, people with weakened immune systems and pregnant women. About 30 percent of cases occur in newborns within the first three weeks of life.
Infections occur throughout the year.
Although most cases occur sporadically, foodborne outbreaks do occur. Listeria bacteria are widely distributed in nature and can be found in water and soil. Infected animals may also serve as sources. Unlike other organisms, listeria can be spread by several different methods. In newborn infections, the organism may be transmitted from mother to fetus in utero, or directly to the fetus at the time of birth.