Brucellosis Brucellosis Brucellosis is a highly contagious zoonosis caused by ingestion of unpasteurized milk or undercooked meat from infected animals, or close contact with their secretions. It is also known as undulant fever, Malta fever and Mediterranean fever. "Brucella" species are small, gram-negative, nonmotile, nonspore-forming, rod-shaped (coccobacilli) bacteria. They function as facultative intracellular parasites, causing chronic disease, which usually persists for life. Four species infect humans: "B. abortus", "B. canis", "B. melitensis", and "B. suis". "B. abortus" is less virulent than "B. melitensis" and is primarily a disease of cattle. "B. canis" affects dogs. "B. melitensis" is the most virulent and
Swine brucellosis nickel transport, "nikA", is activated by metal ion deficiency and is expressed once in the phagosome. Nickel is essential for many enzymatic reactions, including ureolysis to produce ammonia which in turn may neutralize acidic pH. Since "B. suis" is unable to grow in a strongly acidic medium, it could be protected from acidification by the ammonia. Summary: The most frequent clinical sign following "B. suis" infection is abortion in pregnant females, reduced milk production, and infertility. Cattle can also be transiently infected when they share pasture or facilities with infected pigs, and "B. suis" can be transmitted by cow’s milk.