Abstract
Brucellosis is a zoonotic disease caused by Brucella species, a small, Gram-negative coccobacilli group, with four species (B. melitensis, B. abortus, B. canis, and B. suis), causing illness in humans. These bacteria have a different type of outer membrane containing lipopolysaccharides (LPS) compared to similar bacteria like those in the Enterobacteriaceae family. Symptoms typically begin with a sudden fever, and as the illness progresses, it can enter into chronic stage characterized by recurring episodes of fever, along with symptoms such as weakness, sweating, and general discomfort. Human brucellosis is caused by various strains of Brucella bacteria, including B. abortus (from cattle), B. melitensis (from sheep and goats), and B. suis (from hogs). While infections from B. canis (from dogs) are infrequent, they have been reported. Among these, B. melitensis and B. suis tend to be more potent in terms of their pathogenicity. Farm animals, raw dairy products, and wild animals such as deer, bison, horses, moose, caribou, hares, chickens, and desert rats can carry brucellosis, which can also infect humans. In this chapter, we will discuss how brucellosis is contracted and the diseases it can cause. We will focus on Iraq, where brucellosis is a common disease.