Bovine brucellosis, or Brucella abortus, is a bacterial disease that affects a cow’s reproductive system, causing it to abort. It will also affect the entire herd.

Dr Dzunisani Ngobeni, CSS veterinarian with the Gauteng Department of Agriculture and Rural Development (GDARD), explains that the disease is introduced onto a farm when an infected cow calves or aborts in the farm environment, shedding the bacteria.

Predators can also bring infected material onto the farm, making biosecurity an important feature of disease control.

“Cattle that are not infected contract the disease when they are exposed to infected birth material, such as the placenta, infected foetus, and vaginal or birth fluids, via the mucous membranes or via ingestion of the material.” Heifers born from infected cows, are infected during gestation.

Clinical signs that point to brucellosis in the herd include stillbirths and abortions. Cows may also develop metritis and suffer from a retained placenta. Bulls can suffer from orchitis and epididymitis, leading to decreased fertility in the herd. Bulls do not routinely spread the disease through natural mating. Artificial insemination with infected semen can transmit the disease to the cow.

Only buy tested animals

Prevention is best achieved by vaccination and buying animals that tested negative from a herd that has been declared Brucella free. “If a farmer suspects that his/her herd is infected with brucellosis, it is crucial to immediately contact his/her private and state veterinarian. This way, the animals can be tested, and the disease managed and controlled. During this time, it is important that no cattle are allowed to enter or leave the herd or farm,” says Dr Ngobeni.

Farmers, farm workers, veterinarians, abattoir workers and the public are warned to take note of the zoonotic potential of brucellosis. “This means that it can be spread to humans. The disease can be contracted by coming into contact with contaminated birth matter. It is therefore necessary to wear protective clothing when assisting an infected animal and to follow proper hygiene practices.”

Dr Ngobeni further warns that the general public can also contract the disease via ingestion of unpasteurised milk from infected cattle. Clinical signs in humans include flu-like symptoms, night sweats, back pain, chronic fatigue and muscle aches. It is imperative to immediately visit your medical practioner if you suspect that you might have contracted brucellosis. Early detection is very important for successful treatment.

Dr Gillian Declercq, community state veterinarian with GDARD, warns that the impact of brucellosis occurs at two levels. “The first is financial due to the loss of calves, animals that have to be culled, and decreased milk production. This, however, also has an impact at a social level due to smaller herds, loss of herd growth, the impact on the subsistence value of livestock for families, as well as human infection.”

An abortion storm

“The impact of this disease on our livestock industry is significant,” says Dr Declercq. “When brucellosis enters a herd – usually through a newly purchased animal that has not been tested or had contact with a neighbour’s animals due to shared grazing – it usually results in an abortion storm, if the cows have not been vaccinated before.

Most, if not all, pregnant animals in a herd will spontaneously abort, usually within a few days of each other. When a cow aborts, her milk production is severely hampered, which is a massive problem for dairies or those relying on the cow’s milk for subsistence.

Dr Declercq further explains the protocol in place to control the disease. “As a controlled disease in South Africa, we implement a test and slaughter system. In short, veterinarians test susceptible cattle. If these cattle test positive a request for culling will be made. We also vaccinate against the disease to limit its spread. We have a problem though – the brucellosis control scheme is voluntary in South Africa and no farmer is forced to test, slaughter or vaccinate.” – Marike Brits, Stockfarm

This article is part of a series of informative animal health articles. The series goes hand in hand with the #VideoVet video series that can be viewed on Watch the video below.

For more information, contact your MSD Animal Health representative or phone 011 923 9300. (ZA/ORUM/0218/0003e)


Reg. No. G3056 (Act 36/1947).
Namibia Reg. No. V03/24.4/756 NS0
Composition: Lyophilised vaccine containing
the RB-51 strain of Brucella abortus.
Indications: For use in healthy female cattle
as an aid in the prevention of infection and
abortion caused by Brucella abortus.
Dosage: 2 ml subcutaneously.
Pack size: 5 dose (rehydrate to 10 ml);
25 dose (rehydrate to 50 ml).

For full details please read product insert or visit

Thank you for the support of several role-players in creating this series: the Gauteng Department of Agriculture and Rural Development, Dr Gillian Declercq and the CCS veterinarians (Dr Dzunisani Ngobeni, Dr Lindsay Parvess and Dr Heidi Kuhn), MSD Animal Health, as well as Kenneth Ndlovu and the Amogelang team for their assistance and animals for demonstration.