The most important aspects of bovine Brucellosis
Dr C N Sparks BVSc
Brucellosis in cattle (contagious abortion ) is caused by the bacterium Brucella abortus bovis. The disease was reasonably under control in the past, but has become a much bigger threat for cattle farmers in the past few years. Infected cattle also pose a huge risk for game farmers , especially those farming with Buffalo. A recent documentary on the disease was aired by Carte Blanche, if you haven’t seen it go to the following link to view the video clip: http://carteblanche.dstv.com/player/1108464/ Below are ten important aspects of the disease that all cattle farmers must be aware of:
- It is a zoonosis which means that humans are also affected with serious symptoms and consequences. Treatment in humans is difficult and not always effective. People are infected through contact with the placenta or uterine discharge of an infected cow/heifer i.e. when assisting with difficult calving or removal of a retained afterbirth. It may also be contracted by drinking of unpasteurized milk and milk products from infected cows. (Cows are infected by licking infected placentas and uterine discharge or eating feed contaminated by such material.) One infected cow can discharge 100 million bacteria in her placenta!!
- The disease has increased in frequency during the past few years and CANNOT be ignored.
- Infected cows and heifers are infected life long and act as a permanent source of infection for other animals and humans. There is no treatment in animals.
- The first symptom seen when a herd is infected for the first time is abortions (usually at 4 to 7 months gestation) or calves are born early or stillborn. Retained afterbirth is also common. Sometimes swollen, non-painful joints are seen in adult cattle, but infected animals usually appear perfectly normal.
- The economic losses suffered by farmers are due to loss of calves, longer inter calf periods, slaughter of infected animals and loss of milk production
- Brucellosis in cattle is easily diagnosed in a herd with blood tests.
- It is a state controlled disease and all positive or suspicious cases must be brought to the attention of the State veterinarian.
- The disease can be prevented by vaccinating all heifers between 4 and 8 months of age with the S19 or RB51 vaccines. This single vaccination is however not sufficient and must be followed up with at least two more RB51 vaccinations. Do not rely on vaccination only — all the management practices mentioned here must be followed. Remember that the S19 vaccination can interfere with testing and is thus not to be administered to animals older than 8 months. Be careful not to inject yourself with the vaccine since it can cause disease in humans being a live vaccine.
- Farmers should only buy or allow cattle on their premises that originate from regularly tested herds where the seller practices sound management to prevent the disease. Do not only rely on negative test results, especially when buying pregnant heifers, as they may only test positive in the latter third of pregnancy. All animals bought in must be put in quarantine and only released into the herd after the results are known. Better still — do not allow them onto the farm before then.
- The risk for infection is increased by: Not vaccinating against the disease, buying animals from non-tested herds, not keeping fences in good shape, sharing grazing, speculating with cattle and by not regularly having your herd tested.
Do not think that it won’t happen to you — especially if one or more of the above are not complied with. Make sure your neighbours are familiar with the disease and that they do the necessary to prevent it. If we all work together the disease can be kept at bay. Please contact your vet for more information.