Brucellosis in Sheep

​​​​Whilst most farmers know brucellosis means trouble, many are unsure of the exact nature of the disease. Brucellosis is the name given to the disease caused by the Brucella family of bacteria.

There are five Brucella bacteria each causing a different form of the disease.

  • Brucella abortus - affects cattle, causing bovine brucellosis (contagious abortion) - sometimes affects horses, causing fistulous withers.

  • Brucella ovis - affects sheep, causing ovine brucellosis.

  • Brucella melintensis - mainly affects female goats, causing caprine brucellosis - can also affect female sheep.

  • Brucella suis - affects pigs, causing swine brucellosis - it has also been isolated from horses.

  • Brucella canis - affects dogs, causing canine brucellosis.

The Brucella diseases occur throughout the world and, excepting ovine brucellosis, are zoonotic, that is they can be spread from animals to humans.

Brucellosis in humans caused by Brucella abortus was known as undulant fever in Australia, before this disease was eradicated. It is an occupational disease of people who work with animals, such as veterinarians, farmers and abattoir personnel.

In animals the Brucella bacteria localise and multiply in the reproductive organs. In males this often results in reduced fertility. Pregnant females can suffer abortion, stillbirth or early death of the offspring when the uterus becomes infected.

The disease can spread to other animals if they eat infected afterbirth, fluids or any contaminated feed.

Brucella bacteria can also localise in mammary glands (infecting milk) and in limb joints (causing arthritis).

Symptoms in sheep

Ovine brucellosis mainly affects rams, causing lesions in their reproductive organs.

Affected rams develop hard, abscess-like swellings in the epididymis, which is closely attached to the testicles, particularly at the lower end. These lesions are most noticeable because they are so much harder than the rest of the epididymis and also because the swellings are irregular in size making one epididymis feel quite different in shape from the other. Normally, there is no significant difference in shape between a pair of epididymii. Rams may become permanently infertile.

The disease is transmitted at joining when a clean ram serves a ewe that has recently been served by an infected ram in the same cycle. Rams can also transmit the disease between themselves through homosexual activities. Ewes although fairly resistant to the disease, can be carriers of the infection for extended periods, resulting in abortions and discharge of the organism in the placenta, vaginal discharges and the milk.

Ovine brucellosis is not known to cause disease in humans.

​​Tasmanian Ovine Brucellosis-Free Accreditation Scheme

The Department of Natural Resources and Environment Tasmania in conjunction with veterinary practitioners and industry, has developed a voluntary ovine brucellosis accreditation scheme to control the disease in Tasmanian flocks. Approved private veterinary practitioners carry out the accreditation assessments including testing and farm assessment, accredited flock owners manage the biosecurity risks to maintain their flock’s status, and the Department currently administers the scheme.

Before a flock can be accredited as being 'free of ovine brucellosis' applicants will need to have a good understanding of the risks of disease introduction. Their approved veterinarian can assist in the development of a property management plan that addresses these risks. Then all rams and teasers over four months of age must be blood tested according to the scheme conditions and their origin. If tested negative and an appropriate property management plan is in place, the flock may become accredited. Fees are charged by the administrator for initial accreditation and renewals. 

For a flock to maintain an 'ovine brucellosis free' status, all rams eligible for testing must be reassessed every two years following initial accreditation.

There are other scheme conditions addressing various scenarios that accredited-free flock managers may encounter. For instance, the introduction of rams and ewes from accredited or unaccredited flocks, re-accreditation after suspension due to the detection of Brucella ovis infection.

Approved Veterinarians for the Tasmanian Ovine Brucellosis-Free Accreditation Scheme:

 Public Register of Approved Veterinarians for the Ovine Brucellosis-Free Accreditation Scheme (PDF 102Kb)

Ovine Brucellosis-Free Accreditation Scheme Schedule:

 Ovine Brucellosis-Free Accreditation Scheme Schedule (PDF 609Kb)

​Application forms:​

 Application for Initial Accreditation Under Ovine Brucellosis-Free Accreditation Scheme (PDF 249Kb)

 Application for Renewal of Accreditation Under the Ovine Brucellosis- Free Accreditation Scheme (PDF 239Kb)

Owners of accredited flocks can request that their flock accreditation details be available on a public register, which can be accessed through the Animal Health Australia website.  It is important to note that some flock owners that have accredited their flocks have chosen not to include their details on this public register.​

More information about the Ovine Brucellosis-Free Accreditation Scheme is available from NRE Tas:

Phone: 1300 368 550

Or contact an approved veterinary practitioner as listed in the Schedule of Conditions of the Ovine Brucellosis-Free Accreditation Scheme.​

Other forms of brucellosis

None of the three forms below of the disease occur in Tasmania:

  • Swine brucellosis is a disease that affects reproduction in pigs. Although abortions are unusual, stillbirths are common and young piglets born with the infection have a high mortality. The disease appears to be confined to the north of Australia, occurring mainly in Queensland.

  • Canine brucellosis causes abortions and infertility in dogs. It does not occur in Australia but has been reported in all the other continents except Africa. Dogs from the UK must be tested for canine brucellosis and found negative before they can be imported into Australia.

  • Caprine brucellosis causes abortion and udder infection in goats and sheep. The disease does not occur in Australia but it is common in the Mediterranean region, Asia and Latin America. The bacterium responsible can also infect humans, causing Malta Fever. Human infection usually occurs from consuming contaminated milk, milk products or uncooked meat.

Note: horses occasionally become infected with Brucella abortus and Brucella suis, with the problem then called 'fistulous withers'. 

Chronic draining abscesses occur, usually in the withers region (above the shoulder), and surgery may be necessary to completely clean up the infection. Because Brucella abortus is involved there is an added risk that the infection can be transferred to humans or other animals, especially cattle. In Australia, however, horses are free of Brucella abortus bacterium because of the eradication program for bovine brucellosis.​


Animal Disease Enquiries

13 St Johns Avenue,
New Town, TAS, 7008.