Brucella are the gram-negative, facultative intracellular pathogens that may cause severe disease in both humans and animals. Brucellosis, a disease caused by Brucella, is believed to be an ancient disease that was described more than 2000 years ago by the Romans. Brucellosis remains endemic in many developing countries, causing important economic losses. Brucella abortus infects cattle provoking abortion and infertility, but can also infect humans producing undulant fever, endocarditis, arthritis and osteomyelitis. The interest in brucellosis has been increasing because of the growing...