Brucellosis is an infectious disease caused by bacterial pathogen Brucella. Brucellosis in humans most often arises from the ingestion of unpasteurized milk products or raw meat from animals infected with brucellae, which are gram-negative facultative intracellular bacteria. Brucella also poses as an occupational hazard for meat processors, livestock handlers, and veterinarians, as a result of exposure to contaminated meat and blood. Pulmonary disease has been reported in which infection possibly resulted from exposure to contaminated aerosol. Brucella has been weaponized by several countries as a possible biological warfare agent. While not life-threatening in humans, brucellosis can cause disease with relapses of undulating fever and lifelong complications, including arthritis, endocarditis, and possible neurological symptoms, despite antibiotic treatment. In addition, Brucella causes disease and abortion in many of the agricultural animals in the world resulting in wide-spread economic losses.