Ask the vet: Brucellosis – what you should know

By Dr Sello Maboe

In the battle against Covid-19, vaccination against disease has received a further boost globally as a cornerstone of preventative healthcare. Its importance in managing feared brucellosis cannot be overemphasised. Prevention is and always will be better than cure. Here’s what you should know about your role and responsibilities as a livestock producer.

WHAT IS BRUCELLOSIS?

This disease is also known as contagious abortion (CA) and occurs mostly in cattle. Brucellosis is one of the most common zoonotic (meaning it can be transmitted to humans) bacterial diseases worldwide.

In South Africa it is a state-controlled disease, in terms of the Animal Diseases Act, 1984 (Act no 35 of 1984), making the vaccination of eligible animals compulsory. Disease transmission to other susceptible animals is mainly oral (through the mouth), either through contaminated pastures or through direct contact with infective material.

Latrogenic (through contaminated instruments) and aerosol transmission are common, but transmission through other vectors has also been reported. Wild carnivores and dogs are among these vectors, as they drag infected afterbirths across pastures contaminating them in the process. The bacteria can also be washed from infected farms onto neighbouring farms, especially during heavy rains.

THE DISEASE AND FARMERS

Brucellosis causes huge economic losses in the animal industry and poses a serious threat to human health. Some of the observed losses include reduced fertility, abortions, poor weight gain, lost draught power and a substantial decline in milk production. Severe illness and death in animals have also been reported.

Affected animals include cattle, swine, goats, sheep and dogs, whereas humans contract the disease through direct contact with infected animals by eating and drinking contaminated animal products or by inhaling airborne bacteria. Some of the costs include the cost of disease eradication and prevention. Every player in the animal industry can make a meaningful contribution in preventing the spread of the disease and in its eradication.

The farmer’s priority is to honour the legal obligation of ensuring that all heifers are vaccinated with a registered vaccine between the ages of four months and eight months. Although CA is a state-controlled disease, the state may not always be able to provide vaccines. Farmers are well advised to embrace the responsibility as owners and investors to protect their own assets when it comes to disease prevention. Once animals are infected, there is no cure. Vaccination has been by far one of the most effective ways to prevent CA.

The global eradication of rinderpest from cattle herds shows how effective vaccination can be in disease control. Buy breeding animals from herds known to have negative brucellosis status, preferably certified negative by the state veterinarian in the area. When buying animals from a farm with no known disease history, quarantine the animals and test for brucellosis during quarantine.

Other key facts to take into account:

■ Brucellosis is a herd disease. One cannot rely on the test result of a single animal as an indication of the source herd’s disease status. The entire herd’s disease history becomes important, as some of the animals may be incubating the disease at the time of testing.

■ It affects your income negatively. There will be fewer weaners to sell if the herd is infected, owing to pregnancy losses and even deaths.

■ Buying infected animals is a disaster. This is probably even more devastating if you know you went out and purchased your own problems and had them delivered to the farm. Animal movement by humans is among the most common ways diseases are spread over long distances, often even across provincial and national borders.

■ Humans can get sick from brucellosis. The impact of infections in a human population already dealing with other multiple health challenges can potentially worsen the situation in the animal industry.

■ Vaccination in South Africa is compulsory. It remains every farmer’s responsibility to make sure that eligible animals are vaccinated with a registered vaccine to prevent this disease.

ADVANTAGES OF HAVING A VACCINATED HERD

■ Healthy animals. Healthy or at least brucellosis-free animals will not have their fertility negatively impacted by the disease. This is especially important considering that heifer calves of infected cows will highly likely be infected, further propagating the disease within a herd.

■ Improved human health. Farmers and animal health professionals who work closely with animals are at high risk of exposure. Having a vaccinated herd means you reduce the transmission risk to humans. Vaccination also protects consumers of animal products (especially unpasteurised dairy) from exposure to brucellosis.

■ Agricultural sustainability. A disease-free herd means productive farming and the ability to sell excess heifers, which contributes to profitability.

■ Reducing reliance on antimicrobial agents. Animals infected with brucellosis cannot be treated. Infected humans may need prolonged antibiotic therapy to manage the disease.

Speak to your local veterinarian or animal health technician about brucellosis and basic vaccination programmes.

Dr Sello Maboe is the technical and marketing manager at Onderstepoort Biological Products. Email him at sello.maboe@obpvaccines.co.za