Listeria monocytogenes (Listeria) is a dangerous foodborne pathogen commonly associated with dairy product outbreaks. Listeria infection has remarkably high hospitalization and mortality rates, thus the FDA implements a zero-tolerance policy for Listeria in ready-to-eat products. Listeria is also a common pathogen of dairy animals, such as cattle, sheep and goats. Although most adult cattle have a high tolerance for Listeria infection, this pathogen can cause encephalitis (circling disease), death in young calves and abortion in pregnant animals. Additionally, fecal shedding of Listeria is very common in dairy cattle, who often show no symptoms. This may increase transmission within the herd, particularly compromising susceptible animals. Additionally, shedding increases the likelihood of dairy product contamination with Listeria. This project will evaluate Listeria samples obtained from Wisconsin dairy cows for antibiotic resistance, outbreak potential and environmental persistence, as well as investigate the mechanisms behind cows with Listeria having no symptoms. The findings will inform treatment and intervention strategies to enhance animal health and food safety. This research will be conducted with guidance from Tu-Anh Huynh, assistant professor of food science.