Bovine Brucellosis Study Guide

Overview and Clinical Importance

Bovine brucellosis (also known as Bang's disease or contagious abortion) is a highly contagious bacterial zoonosis caused primarily by Brucella abortus. This disease represents one of the most significant reproductive disorders in cattle worldwide and is a major zoonotic concern, with infection in humans causing undulant fever (Malta fever). The NAVLE frequently tests knowledge of brucellosis due to its public health significance, regulatory importance, and the critical role veterinarians play in surveillance and control programs.

In the United States, brucellosis has been largely eradicated from domestic cattle through rigorous test-and-slaughter programs combined with calfhood vaccination. However, a wildlife reservoir persists in bison and elk in the Greater Yellowstone Area, creating ongoing spillover risks to domestic livestock. Understanding brucellosis is essential for any veterinarian working with cattle, particularly in regulatory veterinary medicine.

Etiology

Causative Agent

Brucella abortus is the primary causative agent of bovine brucellosis. It is a small (0.5-0.7 x 0.6-1.5 micrometers), Gram-negative, facultative intracellular coccobacillus that is non-motile, non-spore-forming, and aerobic (may require added CO2 for primary isolation). The organism belongs to the Alphaproteobacteria class and is closely related to plant pathogens such as Agrobacterium tumefaciens.