National Agricultural Biosecurity Center

Listeriosis

Listeriosis, also known as "circling disease" and "silage sickness," is a serious bacterial infection caused by the bacterium Listeria monocytogenes. L monocytogenes is ubiquitous in the environment and has been isolated from raw meat, dairy products, vegetables, and seafood. There are 13 serovars of L monocytogenes; and, although all are considered to be potentially virulent, serovars 4b, 1/2b, and 1/2a cause most animal and human disease. Wild and feral mammals, birds, fish, and crustaceans serve as reservoirs for this infection as well as soil. Infected animals can shed L monocytogenes in their feces, milk and uterine discharges. In the United States, listeriosis is recognized as one of the important public health problems. According to the CDC, there are an estimated 2,500 cases of serious listeriosis each year, approximately 500 of which are fatal. This disease affects primarily pregnant women, newborns, and adults with weakened immune systems.

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