Etiology: the Genus Brucella

Abstract

Brucellosis is caused by bacteria of the Brucella species. Twelve species have been identified in the genus. In this chapter, we address the taxonomy and phylogenetic relationships of the presently recognised Brucella species and biovars, as well as as Brucella morphology and metabolism and epidemiological features of the Brucella species. Brucella melitensis and B. ovis are the aetiological agents of small ruminant brucellosis. B. melitensis may infect both, goats and sheep, producing a disease mainly characterised by abortion, retained placenta and birth of weakened offspring, while B. ovis is pathogenic to sheep, inducing epididymitis and decreased fertility in males as main symptoms. B. melitensis is the main agent of zoonotic brucellosis, while B. ovis has lower zoonotic significance. Other Brucella species have negative impact on public health. Given the recent knowledge about the genus Brucella, it is worth describing the most relevant characteristics of the different species. Therefore, a short description of each species is presented.