Brucella abortus mainly causes disease in cattle. However, there are also other species of Brucella bacteria that primarily cause disease in domestic animals other than cattle. Most of these diseases are zoonoses (able to cause disease in humans) and can infect multiple species.
Brucella melitensis is primarily a disease of goats, but can infect many other species, including sheep, cattle, dogs and humans. Infected goats show similar signs to cattle with brucellosis i.e. they have reproductive problems such as infertility and abortions while appearing otherwise healthy. Humans can catch brucellosis from goats when they come into contact with infected body fluids such as aborted foetuses and foetal membranes, afterbirths and blood.
Brucella canis is a disease of dogs, causing many of the same signs seen in humans infected with brucellosis. Infected dogs in South Africa usually show back pain from discospondylitis (inflammation of the intervertebral discs in the spine), which causes them to walk with a painful, hunched posture. Infected dogs can also suffer from reproductive problems and infertility. Humans can catch brucellosis from infected dogs through contact with their body fluids.
Brucella suis does not exist in South Africa, but causes disease in pigs and wild animals in many other parts of the world. It is a zoonosis. Signs of brucellosis that should be looked out for in domestic pigs are reproductive problems including abortions, stillbirths and small litter sizes.
Brucella ovis infects the testes of and causes infertility in rams. Brucella ovis can also infect red deer, but otherwise has not been seen to infect other species of animals. This species of Brucella is not a zoonosis, so people don’t have to worry about catching it if their sheep are infected.
Lesley Van Helden