The Namibia Agricultural Union in their on Friday 9 May Newsletter urged farmers to be vigilant in protecting their animals against Brucellosis that can infect animals and humans.
Brucella is a group of bacteria that primarily affect the reproductive systems of animals and causes longstanding flu-like symptoms in people.
Different Brucella bacteria target different animals: B. abortus targets cattle, B. melitensis affect goats and sheep, B. suis occurs in pigs, and B. canis targets dogs.
The article in the NAU newsletter focuses on Brucella abortus, which leads to significant economic losses in cattle herds and poses a health risk to humans.
Brucellosis in cattle causes abortions, stillbirths, retained placentas, and reduced milk production. The infected animals excrete the bacteria through aborted foetuses, placenta, and milk, thereby increasing the risk of contamination and the spread of the disease.
Identification of the disease is complicated because the cattle may appear healthy, but since it is a herd disease, if one animal is infected, one can assume that the herd is potentially at risk.
Female animals
Infected pregnant heifers and cows typically abort only once and may appear healthy, which is misleading. These animals may abort and become temporarily infertile, leading to extended calving intervals and decreased production.
Also, these female animals continue to spread the infection through the placenta and milk, causing significant financial and production losses.
Transmission mostly occurs when an infected animal gives birth or aborts, releasing the bacteria into the environment, thereby infecting other animals and humans.
Heifers born to infected cows often test negative until their first calving. They should be kept separate from the herd until they have calved and tested negative for the disease.
Aborted foetuses and placentas can be further spread by stray dogs, jackals, and crows that scavenge on them. Flies feeding on infected materials can also mechanically transmit the bacteria when they land on the nasal mucous membranes of animals.
Humans
As a zoonotic disease, brucellosis can be transmitted from animals to humans through direct contact with infected material, including aborted foetuses or placentas, or by consuming unpasteurized milk and dairy products from infected animals. In humans, the disease can cause serious complications, including fever, joint pain, and sometimes chronic health issues.
Government’s responsibility
Under the Animal Diseases Act, Act 1 of 2011, Brucellosis is a notifiable animal disease, which means any positive cases must be reported specifically to the Chief Veterinary Officer (CVO) of the Directorate of Veterinary Services (DVS).
The DVS’s role in managing a notifiable animal disease includes monitoring, prevention, and control. They are responsible for monitoring outbreaks and developing and implementing public health policies. Veterinarians have a role to play when blood samples test positive in a laboratory.
Vaccination
Vaccination helps protect your herd against the disease and prevents its spread and the number of abortions.
The law requires that heifer calves between the ages of three to eight months must be vaccinated once with a registered vaccine (S19). The age is important, because if the S19 vaccine is administered at an older age, the animal may continuously test positive in blood tests, causing confusion about its disease status.
Non-pregnant heifers can be vaccinated with the RB51 vaccine, and cows can be vaccinated at any time, as it does not result in positive blood test results.
Non-pregnant heifers or cows should be vaccinated twice with RB51, with the first dose administered between four to ten months of age, followed by a booster at twelve to sixteen months.
Do not vaccinate bulls with either the S19 or RB51 vaccines, as it can render them sterile.
Owner’s responsibility
Owners are responsible for the health of their animals and can be prosecuted under the Animal Diseases Act if they contribute to the spread of Brucellosis.
Measures to prevent the spread includes insisting on information about the origin and vaccination records when buying animals. If available, proof of negative herd test results should be provided.
For biosecurity purposes, it is important to keep newly acquired cattle in isolation, test them for diseases, vaccinate them and treat them for internal and external parasites before adding them to an existing herd.
Source references
Brucellosis: A threat to livestock and humans Brucesllosis_NAUnews_09May2025.pdf
Brucellosis and the risk for humans (2021) ProAgri Media https://proagri.co.za/brucellosis-and-the-risk-for-humans/
Madzingira, O., Aikukutu, G., Kandongo, F., Kolo, F.B., Haiseb, S., Tjipura-Zaire, G., Kabajani, J., Musilika-Shilongo, A., Van Heerden, H. (2023) Seroprevalence, and molecular detection of Brucella abortus in cattle tissues from an abattoir in Namibia. PMCID: PMC10308871 PMID: 37398877
https://pmc.ncbi.nlm.nih.gov/articles/PMC10308871/
