ABSTRACT
Guides for Emergency Response: Biological Agent or Weapon: Brucellosis Brucellosis is a systemic zoonotic disease caused by one of four species of bacteria: Brucella melitensis, Brucella abortus, Brucella suis, and Brucella canis with virulence for human beings decreasing somewhat in the order used here. Th ese bacteria are small gram-negative, aerobic, non-motile (not exhibiting or capable of movement) coccobacilli that grow within monocytes (a large leukocyte with fi nely granulated chromatin dispersed throughout the nucleus that is formed in the bone marrow, enters the blood, and migrates into the connective tissue where it diff erentiates into a macrophage) and macrophages (a phagocytic tissue cell of the reticuloendothelial system that may be fi xed or freely motive, is derived from a monocyte, and functions in the protection of the body against infection and noxious substances). Th ey reside quiescently in tissue and bone-marrow, and are extremely diffi cult to eradicate even with antibiotic therapy. Th eir natural reservoir is domestic animals, such as sheep, goats, and camels for B. melitensis; cattle for B. abortus; and pigs for B. suis. Brucella canis is primarily a pathogen of dogs, and only occasionally causes disease in humans.
