Livestock in South Africa such as sheep, goats and cattle are currently at high risk of contracting Rift Valley fever, veterinarians and national producer organisations have warned.
By Vida Booysen, senior journalist at African Farming and Landbouweekblad
Heavy rainfall across large parts of the country and pans of standing water where mosquitoes hatch and multiply are creating favourable conditions for transmission of the virus that causes Rift Valley fever (RVF).
Large-scale outbreaks occur roughly every 10 to 15 years in South Africa. Severe outbreaks were recorded in 1974/75 and 2010/11, with smaller sporadic outbreaks in between.
The most recent case was recorded in November 2025 in a sheep flock in the Northern Cape. Since then, experts have been closely monitoring the situation, concerned that it may be an “early warning sign” of further outbreaks following the good summer rains.
Also read: One outbreak can wipe out your breeding season: Rift Valley fever warning for SA farmers after heavy rains
Vaccination the Most Effective Protection
Annual vaccination against this notifiable disease remains the most effective protection. But because major outbreaks occur at long intervals, many farmers do not vaccinate their livestock every year.
“This means we currently have a large number of naïve animals [animals that have never been vaccinated and have no protection against the virus], and that creates significant risk,” says Dan Kriek, general manager of the National Wool Growers’ Association (NWGA).
The virus affects various species, but sheep are the most severely impacted. Goats, cattle and even buffalo can contract the disease. Rift Valley fever can also be transmitted to humans, particularly when handling sick or dead animals.
“When we look at the patterns of previous major outbreaks, we are very concerned,” Kriek says. “We want to urge farmers to make regular, timely vaccination against Rift Valley fever a standard practice on their farms – even during the long periods between major outbreaks.”
He says the NWGA is engaging with the relevant authorities to ensure the country is better prepared to prevent a catastrophic outbreak such as the one in 2010/11.
Also read: Rift Valley fever is deadly for humans and animals; vaccinate now
The Right Vaccine for Pregnant Animals
Onderstepoort Biological Products (OBP) manufactures two types of vaccine, one of which may not be administered to pregnant animals. This is the so-called live attenuated vaccine containing the Smithburn strain, which can cause abortions in pregnant animals.
Pregnant animals may, however, be vaccinated with the second type, the so-called inactivated or “killed” vaccine. All animals vaccinated with this product must receive a booster dose a few weeks later.
If a major outbreak similar to that of 2010 were to occur now, South Africa would require vast quantities of the inactivated vaccine, Kriek warns. “In our communal areas, rams and bulls run with the ewes and cows throughout the year, which means animals are pregnant year-round, so the live attenuated vaccine is not an option for them.”
He adds that the available supply of inactivated vaccine in the country must effectively be halved, because each animal requires two doses.
“The NWGA is already in discussions with other industry bodies, such as the Red Meat Producers’ Organisation (RPO) and Mohair South Africa, as well as the relevant authorities, to ensure that if a major outbreak strikes, we will be in a position to administer large quantities of the correct vaccine quickly. However, we strongly encourage farmers to vaccinate their animals against the virus.”
Also read: Rift Valley Fever: Outbreak prevention lies in cattle farmers’ hands
