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Listeriosis is an infection caused by the bacteria Listeria monocytogenes. Persons at increased risk for severe infections include immunocompromised persons, the elderly, pregnant women, and newborn infants. The bacterium is unusual among foodborne pathogens in that it multiplies at low temperatures, including in refrigerated foods. Transmission occurs primarily through ingestion of contaminated drinks and foods, including raw (unpasteurized) or contaminated milk, soft cheeses such as queso fresco, vegetables, and ready-to-eat meats. During pregnancy, infection can lead to spontaneous abortion, stillbirth, or premature birth. Transmission during delivery can cause severe, often fatal, infections in the newborn, even if the mother is asymptomatic.


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