With heavy summer rains increasing mosquito populations across parts of South Africa, Beefmaster Group is urging farmers to take proactive steps against Rift Valley Fever (RVF) – a preventable mosquito-borne viral disease that affects livestock and can also infect humans. If left unmanaged, RVF can severely disrupt an entire breeding season and cause significant financial losses.
What is Rift Valley Fever?
Rift Valley Fever is a viral disease primarily transmitted by infected mosquitoes, especially after periods of heavy rainfall. It mainly affects livestock such as cattle, sheep, and goats, with sheep typically the most severely impacted.
“RVF is a classic ‘after the rains’ disease,” says Thapelo Kgosi “King” Ramokala, Animal Health Specialist at Beefmaster Group. “Young animals and pregnant females are the most vulnerable. Farmers may notice sudden deaths in lambs and calves or a spike in abortions – both key warning signs that require immediate action.”
This warning is particularly relevant following a reported RVF outbreak in the Northern Cape among livestock in late 2025.
How Rift Valley Fever Spreads
RVF spreads primarily through mosquito bites after wet weather conditions. However, transmission can also occur through direct contact with infected animal blood, tissues, or organs.
Farm workers and farmers are at higher risk when:
- Assisting with animal births
- Handling aborted material
- Slaughtering infected animals
- Touching carcasses without protective gear
Importantly, RVF does not spread through casual contact with animals.
Symptoms of Rift Valley Fever in Animals
Recognising early symptoms is critical for preventing widespread outbreaks.
In adult animals:
- Fever and weakness
- Loss of appetite
- Nasal discharge
- Diarrhoea
In pregnant animals:
- Sudden and widespread abortions
In young animals:
- High mortality rates
- Sudden death with minimal warning signs
Symptoms of Rift Valley Fever in Humans
In humans, RVF symptoms are usually mild but can occasionally become severe.
Common symptoms:
- Fever
- Headache
- Muscle and joint pain
- Fatigue
Severe cases may include:
- Eye complications
- Bleeding disorders
- Liver damage
If RVF is suspected, farmers should immediately stop animal movement and contact a veterinarian or state veterinary services. Laboratory testing is required for confirmation.
Prevention: Act Before the Rainy Season
Prevention is the most effective strategy against RVF.
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Vaccination
Vaccinating livestock before the rainy season is the most reliable protection. Always consult a veterinarian, as some vaccines are not safe for animals in early pregnancy.
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Mosquito Control
Reducing mosquito populations can significantly lower infection risk:
- Eliminate standing water
- Use approved insecticides or repellents
- Avoid grazing livestock in wet, marshy areas during high-risk periods
Biosecurity Measures to Protect Livestock and People
Good farm hygiene and biosecurity practices are essential to contain outbreaks:
- Isolate sick animals immediately
- Limit animal movement during outbreaks
- Safely dispose of carcasses and aborted material
- Wear gloves and protective clothing when handling animals
- Clean and disinfect equipment, clothing, and hands
- Avoid slaughtering sick animals
- Cook meat thoroughly and avoid consuming raw milk during outbreaks
Economic Impact of Rift Valley Fever
RVF outbreaks can have devastating financial consequences:
- Loss of livestock due to deaths
- Reduced breeding success from abortions
- Lower milk and meat production
- Trade and movement restrictions
“One outbreak can wipe out a breeding season,” Ramokala cautions. “But RVF can be prevented and managed if farmers act early.”
Final Thoughts: Early Action Saves Herds
Rift Valley Fever is a serious but preventable disease. Early reporting, proper vaccination timing, mosquito control, and farmer education are key to protecting livestock and livelihoods across South Africa.
