Listeriosis is a serious bacterial infection caused by Listeria monocytogenes. It can occur in anyone but mainly affects newborns, pregnant women, the elderly and those with weakened immunity. People become infected by eating contaminated foods such as soft cheeses, raw vegetables and processed meats. Symptoms range from flu-like illness to meningitis. Diagnosis involves culturing the bacteria from clinical samples. Treatment requires intravenous antibiotics. Prevention involves following good hygiene practices and avoiding high-risk foods for vulnerable groups.