Brucellosis is a bacterial infection caused by Brucella species that primarily affects animals but can be transmitted to humans, making it a zoonotic disease. People typically become infected through direct contact with infected livestock, consumption of unpasteurized dairy products, or inhalation of contaminated aerosols. Symptoms often include fever, sweats, fatigue, joint and muscle pain, headaches, and weakness, and the illness may become chronic if not properly treated. Because brucellosis can affect multiple organ systems, it may lead to complications involving the liver, heart, or nervous system. Diagnosis is confirmed through blood tests, and treatment generally requires a prolonged course of combination antibiotics to prevent relapse. Preventive measures include pasteurization of dairy products, protective handling of animals, and control of infection in livestock populations.