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Big 5: The most significant
diseases you currently need to monitor to protect your cattle herd
____________________________________________________
By: DR HENNIE KLOPPER
Over the past three years, the South African livestock
industry has faced significant challenges due to the
recurrent outbreaks of Foot-and-Mouth Disease. This disease
draws a lot of attention due to its devastating impacts on
the country’s economy and export status. However, several
other diseases are often overshadowed by Foot-and-Mouth
Disease and do not receive the necessary attention, even
though they can potentially cause equally significant harm.
The Southern
African climate is primarily characterised by summer
rainfall, which presents both advantages and challenges to
cattle farmers. While these conditions are ideal for
grazing, the warm, humid environment also fosters the growth
of bacteria, viruses, and parasites, making them challenging
to control.
For these
reasons, we emphasise the five diseases that currently
warrant attention for active prevention and treatment,
ensuring that your herd is well-prepared to navigate the
summer months – without the burden of illness – and achieve
a successful breeding season.
1.
LUMPY SKIN DISEASE
Lumpy skin disease is a progressive disease caused by a
virus from the Poxviridae family. It leads to permanent skin
damage, severe declines in fertility, and reduced
productivity in the herd overall.
Risk Period
●
Typically occurs during late summer and early autumn
(January-May).
●
Most prevalent in years with above average rainfall.
Carriers and Transmission
●
Blood-feeding insects, such as stable flies, can rapidly
spread the disease from a single infected animal across a
wide area.
●
Infected animals can transmit the disease within the herd: -
Through salivary contamination in shared feed and water
troughs. - Female animals can transmit the virus to calves
via milk.
●
Farmers and workers can contribute to transmission: - By
using contaminated needles during vaccination. - By using
semen from an infected bull for artificial insemination.
●
Wild animals do not play a significant role in spreading the
disease.
Who is at Risk?
●
Unvaccinated cattle herds are particularly vulnerable, with
transmission rates of up to 85% before intervention.
●
Calves born to unvaccinated cows are vulnerable.
●
Calves born to vaccinated cows benefit from passive
immunity, offering protection for up to six months.
Treatment
●
There is no cure for Lumpy skin disease.
●
Treatment is only symptomatic, making prevention the most
effective approach.
Prevention
●
Annual vaccination is recommended, ideally in spring, before
the start of the rainy season and the subsequent increase in
insect populations.
●
Control of blood-feeding insects can help limit disease
spread.
●
Calves born to unvaccinated cows should be vaccinated as
soon as possible.
●
Calves born to vaccinated cows should receive their
vaccination once they reach six months of age.
●
Pregnant cows can be vaccinated with certain vaccines, but
it is essential to consult your veterinarian to confirm
vaccine safety.
Important Notes
●
Lumpy Skin Disease outbreaks tend to align with rainfall
cycles, causing some farmers to stop vaccination during
drier years.
●
This
inconsistent vaccination schedule can result in the loss of
immunity in some animals, leaving a large portion of the
national herd unprotected and increasing the risk of
widespread outbreaks.
●
Vaccine
shortages can often occur during outbreaks, making it
crucial for farmers to plan in advance.
2.
BOVINE EPHEMERAL FEVER (BEF) ‘THREE-DAY STIFF
SICKNESS.’
This mosquito-borne disease, caused by a Rhabdovirus, leads
to severe declines in cattle health. Dairy cattle are
particularly susceptible, often exhibiting more severe
symptoms such as significant milk losses, pulmonary
emphysema, and increased mortality.
Risk Period
●
Most common during the summer breeding season
(January-April).
●
Occasional cases can occur between October and December.
●
Outbreaks typically coincide with periods of high insect
activity, particularly in late summer and autumn, and
decline sharply after the first frost.
Carriers and Transmission
●
Anopheles
and
Culex
mosquito species.
●
Culicoides
midges.
Who is at Risk?
●
Yearling and two-year-old replacement heifers.
●
Breeding bulls during the mating season.
Treatment
●
Treatment is only symptomatic, making prevention the most
effective approach.
●
Immunity typically lasts a lifetime after an initial
infection, though in rare cases, an animal may contract the
disease a second time, usually if the initial infection was
too mild to develop strong immunity.
Prevention
●
Inactivated vaccines are available, typically requiring two
doses one month apart.
●
Annual booster vaccinations, administered before the risk
period, are recommended for optimal protection.
●
Insect repellents can help reduce transmission by limiting
mosquito bites.
Important Notes
●
The vaccine has low immunogenicity (ability to trigger an
immune response), making the timing of vaccinations crucial.
●
Proper primary and booster vaccination administration is
essential to ensure high immunity levels before and during
peak transmission periods.
3.
TICK-BORNE DISEASES
Tick-borne diseases are a significant cause of economic
losses in South Africa’s livestock industry. African
Redwater
(Babesia bigemina)
and Asian Redwater
(Babesia bovis)
are both caused by protozoan parasites and warrant
additional caution. These parasites target red blood cells,
leading to symptoms such as fever, anaemia, and, if left
untreated, death.
Order of Priority
1. African Redwater
2. Asian Redwater
3. Tick-borne gall sickness (Anaplasmosis)
4. Heartwater (Ehrlichiosis)
Risk Period
●
Tick-borne diseases can occur all year round, especially in
the summer after a period of high rainfall. Although their
prevalence is lower in winter, they can occur all year
round.
●
African Redwater
has been reported in most provinces except for arid areas
like the Northern Cape and Great Karoo.
●
Asian Redwater
is prevalent in Gauteng, Mpumalanga, KwaZulu-Natal, and the
coastal areas of the Eastern and Western Cape.
●
Anaplasmosis
has been reported in the Western Transvaal, North-Eastern
Cape, eastern parts of the Karoo and Central- and Western
Free State.
●
Heartwater
mainly occurs in the warm and humid Lowveld or Bushveld
areas, including Northwest, Gauteng, Limpopo, Mpumalanga,
KwaZulu-Natal, and the Eastern and Western Cape coastal
areas.
Carriers and Transmission
●
The African blue tick (Rhipicephalus
decoloratus)
and the red-legged tick (Rhipicephalus
evertsi evertsi)
can both transmit African Redwater and Anaplasmosis.
●
African Redwater, Asian Redwater, and Anaplasmosis can also
be transmitted by the pantropical blue tick (Rhipicephalus
microplus),
an invasive arachnoid species now widely spread in Southern
Africa.
●
Anaplasmosis is caused by an internal parasite called
Anaplasma marginale.
The prevalence of anaplasmosis depends on the distribution
of vectors, such as biting flies.
●
The bont tick (Amblyomma
hebraeum)
is the vector for the microorganism Ehrlichia ruminantium,
which causes heartwater. Transmission can only occur through
the tick’s nymph and adult stages.
Who is at Risk?
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Animals from non-endemic regions that have no prior exposure
to tick-borne diseases make them highly susceptible. Moving
these animals to the endemic areas increases the risk of
infection and potential disease outbreaks. To minimise this
risk, susceptible animals should be vaccinated before
entering endemic areas.
●
It can take up to six weeks for immunity to develop after
Redwater and Heartwater vaccinations and eight weeks for
Anaplasmosis vaccinations. Therefore, vaccination should be
done well in advance of moving animals from non-endemic to
endemic areas.
Treatment
●
Block treatment for susceptible herds can help prevent
further losses.
●
Antimicrobial agents are readily available for treating
tick-borne diseases: -
Diminazene
can be used to treat African Redwater (four weeks’
protection) and Asian Redwater (two weeks’ protection).
-
Imidocarb
can be used to treat African Redwater (eigth weeks’
protection) and Asian Redwater (four weeks’ protection).
-
Imidocarb and Oxytetracycline
can both be used to treat Anaplasmosis as well, often
yielding better results as a combination treatment.
-
Chlortetracycline
can be mixed into eed to control Anaplasmosis.
-
Oxytetracyclines
can be used to treat Heartwater.
●
Treatment options should be discussed with a local
veterinarian to ensure that the correct active ingredient
and dosages are used for the specific tickborne disease.
Prevention
●
Use contact dips for immediate tick control, but only dip
animals when tick numbers become problematic or harmful.
●
Vaccination is the only long-term solution for inducing
immunity against tick-borne disease. However, vaccine
availability can be inconsistent. A major concern is that
vaccines have been unavailable for extended periods,
particularly during the critical pre-rainy season when
cattle farmers need to vaccinate before blue tick
populations increase and disease transmission rates rise.
●
If transitioning from intensive tick control to a more
relaxed approach, ensure that appropriate vaccination is
administered. Intensive tick control should be maintained
for up to eight weeks after vaccination to allow sufficient
immunity to develop.
●
In endemic areas, where infected ticks are widespread,
animals should be naturally exposed to tick-borne pathogens
at a young age to develop immunity. This natural
immunisation helps prevent disease outbreaks, creating what
is known as a stable disease situation, where tick-borne
diseases do not occur despite the presence of vectors.
●
An unstable disease situation can develop within an endemic
area if tick populations decline significantly due to
excessive tick control or natural factors such as droughts.
Non-endemic areas are those where the tick vectors are
absent.
●
Vaccinate susceptible animals well in advance before moving
them to high-risk tick-borne disease areas:
-
Redwater – at least six weeks before relocation
-
Anaplasmosis – at least eight weeks before relocation
-
Heartwater – at least six weeks before relocation.
Important Notes
Effective parasite control requires a sensible approach to
minimise resistance risks. Recent feedback from
veterinarians suggests that block treatment is becoming less
effective, indicating an increase in medication resistance
among tick-borne disease pathogens. Careful management and
alternative treatment strategies may be necessary to
maintain control.
4.
BRUCELLOSIS “CONTAGIOUS ABORTION.”
A Disease That is Currently Out of Control!
Bovine Brucellosis has earned its reputation as a formidable
disease and is now subject to government control. This
zoonotic bacterial infection can be transmitted to humans,
posing a significant risk to cattle and individuals such as
farmers, herders, and veterinarians who work closely with
them. While abortion is the primary symptom observed in
dairy herds, it is important to understand that Brucellosis
is not a sexually transmitted disease, despite any
misconceptions.
This disease
can be misleading! Cows and heifers infected with
Brucellosis often appear healthy, with abortion often being
the only noticeable symptom. If these animals remain in the
herd, they silently spread the infection, leading to severe
production and economic losses. Infected cows and heifers
often become lifelong carriers of the bacteria and can
contaminate the environment with large quantities of the
organism during calving or abortion.
In susceptible
herds – that are unvaccinated or have no previous exposure –
acute Brucellosis infections can cause 30% to 40% of
pregnant animals to abort in a short period, a phenomenon
known as an “abortion storm”. Abortions typically occur
between five and nine months of pregnancy. In chronic
infections – where Brucellosis has become established in the
herd – the abortion rate decreases, usually only affecting
replacement animals. While a female typically only aborts
once, she remains a permanent source of infection, spreading
the bacteria during estrus or calving. In rare cases,
infected animals may develop Hygromas, which are fluid
accumulations in the joints.
In beef cattle herds where the disease is deemed ‘out of
control’ based on recent reports and statistics, it is
mandatory for all cattle sent to auctions or abattoirs to
test negative for Brucellosis before they can be sold.
Brucellosis is highly contagious and is found in all nine
provinces of South Africa.
Risk Period
●
The risk period can be at any time of the year since
bacteria spread when cows calve or abort.
Carriers and Transmission
●
Most cows become infected by ingesting bacteria through
licking, eating or smelling aborted material, afterbirth, or
vaginal secretions from an infected animal.
●
Infected cows can pass the bacteria to their unborn calves.
●
Calves drinking from infected cows can also become infected.
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Flies can spread the bacteria after feeding on contaminated
material and then coming into contact with cattle’s eyes or
mouths.
●
Using semen from an infected animal can transmit the disease
during artificial insemination.
●
Sexual transmission by infected bulls is extremely rare.
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The disease can easily spread between herds when infected
animals are moved from one farm to another.
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Predators and scavengers can spread infected materials
(aborted fetuses or afterbirth) between farms.
●
Brucella bacteria can spread via runoff water from
neighbouring farms that have infected animals.
Who is at Risk?
●
Unvaccinated cows and replacement heifers.
●
Young suckler calves.
●
Humans can contract the disease by consuming unpasteurised
milk, slaughtering an infected cow, or handling infected
calving materials or aborted fetuses.
Treatment
●
There is no effective treatment for Brucellosis.
●
All cases must be reported to a government-appointed
veterinarian.
●
The disease can be eliminated by testing and culling all
positive cases, including calves born from infected cows
(the bacteria can remain dormant in calves until they reach
breeding age).
●
The herd can only be declared brucellosis-free after two
negative whole-herd tests are conducted at least three
months apart
●
Brucella bacteria can survive in the environment for up to
12 months under ideal conditions. A farm cannot be declared
Brucellosis-free until no positive cases have been detected
for 12 months.
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Eradication requires a combination of test-and-cull
measures, effective prevention strategies, and strict
control of animal movements.
Prevention
●
It is recommended that all new animals be isolated for
testing, vaccination, and treatment of internal and external
parasites.
●
Prevent cattle from grazing in areas contaminated with birth
fluids or aborted materials.
●
All contaminated materials should be properly disposed of by
burning or burial – never left exposed.
●
By law, all heifers must be vaccinated once between four and
eight months of age, using either the S19 or RB51 vaccine.
●
S19 Vaccine – should only be used in heifer calves between
four and eight months. If administered later, the animal may
deliver a false positive test for life, making it difficult
to determine its true disease status.
●
RB51 Vaccine – can be administered to non-pregnant cows of
any age without causing false-positive test results.
●
Bulls should not be vaccinated with either S19 or RB51, as
it may lead to sterility.
Important Notes
●
Heifers born to infected cows often test negative before
their first calving but may test positive afterwards. Newly
purchased heifers pose a high risk and should be kept
separate from the herd until they have calved and tested
negative for Brucellosis.
●
Animals with dormant infections may take up to three years
to test positive, yet they remain a risk to both cattle and
humans during this time.
●
Brucellosis is a ‘herd disease – if a single animal tests
positive, the entire herd is classified as infected and
placed under quarantine due to its chronic nature and slow
onset of symptoms.
●
Animals that initially test negative may later test positive
as the infection progresses.
●
Cattle owners are legally responsible for the health of
their animals and can
face
prosecution under the following acts if they contribute to
the spread of Brucellosis:
- The Animal
Diseases Act, 1984 (Act No. 35 of 1984)
- The Consumer
Protection Act, 2008 (Act No. 68 of 2008)
●
An owner may
not know knowingly purchase and introduce infected animals
into their herd.
●
If an owner
becomes aware of a government-controlled disease in their
herd, they must immediately inform:
- All
neighbouring farmers
- All
prospective buyers
- Any buyer who
purchased animals from them within the past 30 days
●
The above
obligation applies even if the disease is suspected and not
yet confirmed.
5.
RABIES
The Latest Emerging Disease!
Rabies, caused by Lyssavirus, is another
government-controlled disease in South Africa, regulated
under the Animal Diseases Act. Despite medical advancements,
it is one of the oldest known diseases yet remains
challenging to control. As a zoonotic disease, rabies can be
transmitted from animals to humans and is 100% fatal in both
cattle and humans once symptoms appear. The virus causes
severe, acute inflammation of the brain (encephalitis) in
all affected species, often leading to dramatic behavioural
changes in animals.
Warning Signs
●
Rabies should be suspected when domestic animals suddenly
become aggressive or if wild animals suddenly appear tame.
Carriers and Transmission
●
Cattle are typically infected when bitten by a rabid animal,
most commonly a dog or jackal, which are primary carriers of
the virus.
●
In such cases, the carrier will exhibit classic rabies
symptoms and die within 3 to 5 days.
Clinical Signs in Cattle
●
Cattle that bellow unusually loudly, have a hollowed-out
hunger groove due to the inability to eat, and appear to
strain persistently without passing faeces should be
considered highly suspicious for rabies and treated as a
potential danger until the disease is ruled out.
●
Abnormal drooling is another warning sign, particularly when
accompanied by unsteadiness in the hindquarters.
●
Excessive salivation and nasal discharge are early symptoms
that can be mistaken for other diseases, such as
foot-and-mouth disease.
●
In some cases, rabies symptoms in cattle can resemble those
of a foreign object lodged in the throat or oesophagus.
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Initially, infected animals may exhibit increased aggression
or wild behaviour.
Who is at Risk?
●
Any mammal can be infected with rabies.
Treatment
●
There is no treatment for rabies.
●
Once symptoms appear, the disease has already reached its
fatal stage, and death is inevitable.
Prevention
●
Modern vaccines are highly effective when administered
correctly, ensuring strong protection for pets.
●
In the event of a rabies outbreak in livestock,
veterinarians must report cases immediately. Since rabies
occurs in specific regions at certain times, early detection
allows authorities to warn farmers in affected areas.
●
Livestock are not typically included in routine rabies
vaccination programs. However, during an outbreak,
vaccinating animals on neighbouring farms within a five- to
ten-kilometre radius is a crucial precaution to prevent
further spread.
●
The rabies vaccine takes approximately two weeks to become
effective, making early intervention and reliable early
warning systems critical for disease control.
Important Notes
●
The rabies virus can become dormant. After exposure,
symptoms may take up to two years to appear.
●
If rabies is suspected, contact a government- or private
veterinarian immediately so the animal can be euthanised,
and its brain can be submitted for diagnostic confirmation.
●
Anyone who has had direct contact with the saliva of a rabid
animal should receive a series of four follow-up
vaccinations as a precaution.
Acknowledgements
A
sincere thank you to Dr. Danie Odendaal of the Veterinary
Network, RMIS, and
RuVASA for providing the Disease Overview - October 2024.
The Veterinary Network manages the disease reporting system
in collaboration with the Ruminant Veterinary Association of
South Africa (RuVASA). Reporting is primarily conducted by
private veterinarians working in the livestock industry, who
submit monthly disease observations from farm-level cases.
About the Author
Dr Hennie Klopper earned his veterinary degree in 2014 from
the University of Pretoria’s Onderstepoort Faculty of
Veterinary Science. He practised in the Free State for six
years before relocating to Pretoria. For two years, he
served as Director and Veterinarian at Red Farms Agripark,
overseeing the management of approximately 1500 dairy cattle
until the passing of the late Mr. Johan Bosch. Afterwards,
Dr. Klopper joined a veterinary practice in Bapsfontein
before establishing his practice in Bashewa, East Pretoria.
His primary areas of interest include reproductive health
and herd management, focusing on production animals,
wildlife, horses, and exotic birds. He frequently travels
across South Africa for avian veterinary work, allowing him
to explore diverse regions and their unique biodiversity.
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