Vaccinate now to guard animals against Rift Valley fever

Officially, the next Rift Valley fever outbreak is only expected in 2030, but a leading Afrivet veterinarian believes the latest weather predictions is cause for great concern. When livestock are infected, the virus can cause significant economic losses due to high mortality rates in young animals and waves of abortions in pregnant females

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A leading veterinarian has warned farmers that current weather patterns might be indicative of a possible looming Rift Valley fever (RVF) outbreak. Those who do not vaccinate their animals against the deadly virus, could see alarming abortion rates in cattle, sheep and goats.

Dr Didi Claasen, Afrivet’s executive: technical and marketing support, Photo: Supplied/Food For Mzansi
Dr Didi Claassen, Afrivet’s executive: technical and marketing support. Photo: Supplied/Food For Mzansi

According to Dr Didi Claassen, Afrivet’s executive: technical and marketing support, it is always better to be safe than sorry.

In its seasonal climate watch for August to December 2021, the South African Weather Service predicts above-normal minimum and maximum temperatures across the country.

“These conditions are perfect for some unwelcome guests – notably a boom in mosquito populations,” says Claassen. “Along with biting flies, mosquitoes are carriers of Rift Valley fever, a virus that can be deadly to animals and humans alike.”

South Africa has suffered three major RVF outbreaks since 1951.

Claassen says that, based on historic patterns, the next major outbreak should only occur between 2030 and 2040, but smaller sporadic outbreaks remain a real possibility.

“We should therefore be prepared and act proactively to control this zoonotic disease. The big question looming is: With the current weather predictions, are we possibly facing a RVF outbreak in 2021?” asks Claassen.

She notes that RVF affects mainly sheep, cattle and buffalo. Symptoms in sheep, cattle and goats include so-called abortion storms in which up to 100% of pregnant animals can abort, as well as sudden death in young animals.

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The mortality rate in adult animals is between 10% and 20%, but many will endure symptoms such as a runny nose, fatigue, diarrhoea and fever.

Rift Valley fever is transmitted by mosquitoes and blood feeding flies. Photo: Supplied/University of Surrey
Rift Valley fever is transmitted by mosquitoes and blood-feeding flies. Photo: Supplied/University of Surrey

What about humans?

Humans can also contract RVF when they handle blood or organs from infected animals, or when they drink unpasteurised milk or eat undercooked meat, adds Claassen. Symptoms can range from mild cold or flu symptoms to serious bleeding disorders and even death.

As a precaution, people should only consume meat and milk from reputable sources and vendors and seek immediate medical attention should they suspect that they have contracted RVF.

Claassen says whilst Afrivet supplies several products that could assist in decreasing the mosquito and fly burden around animals (including Deltapor 5 and Icon CS), the most effective prevention strategy is vaccination combined with vector control.

“The only way to prevent or control RVF is to vaccinate herds proactively and to ensure that their immune systems are healthy for the vaccine to work. The time to vaccinate your herd is therefore now. The ideal vaccination timeframe is early spring and, if we consider the weather forecasts, early spring is already at our doorstep.”

Afrivet’s top farmer tips

Did you know that two registered vaccines against RVF are available in Mzansi, both being produced by Onderstepoort Biological Products?

  • The live vaccine is highly effective, provides long-lasting immunity and should be applied annually to ensure continued protection. Do not administer to pregnant animals.
  • The inactivated vaccine is specifically formulated for pregnant animals, given that the live vaccine can induce abortions and foetal deformities. This vaccine is not as effective as the live version, hence a booster, four weeks after the first application, is recommended and thereafter it is boosted annually.
  • During the previous outbreaks there were insufficient quantities of vaccine available at the peak of the outbreak due to a sudden increase in demand. Many farmers could not obtain vaccine for their herd when they needed it the most. It is therefore crucial to order your vaccine now, vaccinate before the rainy season and rest assured that your herd will be protected against large and/or sporadic outbreaks in the coming rainy season.

What every farmer should consider

  • Vaccinate! Non-vaccinated animals are always more susceptible to RVF, warns Claassen.
  • Practice vector control by putting a mosquito and fly management system in place with products such as Afrivet’s Deltapor 5 and/or Icon CS.
  • Report any suspected RVF cases in animals and humans to your local state veterinarian.

ALSO READ: E. Cape MEC applauds Afrivet’s Ngcobo dip tank project

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