Brucellosis and it's Clinical Signs
The Brucella Bacteriums
Brucellosis of cattle, known as "contagious abortion" is caused by infection with the bacterium Brucella abortus, which can also cause a disease of humans known as "undulant fever". Brucellosis of cattle is a notifiable disease which has been eradicated from cattle in Great Britain. However, this disease is the one that poses a constant threat to Scotland from importing cattle.
Brucella melitensis is a bacterial disease which can affect most species of domestic animals, sheep and goats, particularly milking breeds, are the most susceptible. Cattle may occasionally be affected and the disease may appear in pigs.
Clinical Signs
Brucella Abortus: Brucellosis in cattle causes abortion or premature calving of recently infected animals; the foetus, placenta and uterine fluid contain large quantities of Brucella abortus bacteria which can infect other cattle coming into contact with an infected animal around the time of calving. The organism continues to be excreted in the milk; in the past humans were frequently infected through drinking unpasteurised milk. Breeding bulls which are infected, can transmit the disease to cows at the time of service by infected semen.
Brucella Melitensis: Infection is normally by inhalation and via abraded skin, and transmission between species occurs readily. Humans usually become infected by ingestion of affected milk. The post -partum discharges (after - birth) of infected females contain large numbers of bacteria whether or not the animal has aborted. After abortion, infection may persist in the uterus for many months, and in the udder for years.
The level of infection in milk and uterine discharges is probably lower in sheep than in goats. As with Brucella Abortus, viable offspring from infected females may also be infected but seronegative, and may discharge infection following their first parturition or abortion. These animals would thus be a significant risk when imported into an uninfected flock or herd, and it is essential that animals be added only from flocks/herds of known free status.
(This disease has not been reported in Scotland and was last reported in England in 1956.)