Rift Valley fever (RVF) has been confirmed in South Africa’s (SA) Free State Province.
SA’s Department of Agriculture, Forestry and Fisheries (DAFF) has confirmed an outbreak of RVF in sheep near Jacobsdal in the Free State Province. To date, the disease has been detected on 1 farm, with further investigations being carried out by local veterinary services.
“The latest official notification of an outbreak of RVF near Kimberley makes it necessary for farmers to decide what to do. It is risky to leave sheep, goats and cattle unvaccinated since large-scale losses and especially abortions may follow.
“Nobody can be sure of future weather or predict with confidence how next summer’s rains may cause large scale or severe outbreaks, but if everyone waits until such outbreaks occur before vaccinating, there may be large-scale losses since Onderstepoort Biological Products, which makes the vaccine, will be overwhelmed by an avalanche of orders and vaccines will therefore be very scarce.
“Remember that preparing and testing vaccines is a long and exacting process, and cannot be suddenly scaled up to millions of doses. To lower the risk, all non-pregnant ruminant livestock should be vaccinated in the coming winter. For longer term security, vaccinate all breeding replacement livestock before breeding each year as a minimum measure, since it is likely that in most cases effective immunity will be lifelong.
“Farmers are strongly advised to contact their local veterinarian to decide on the risks, the correct vaccines to use, and the best vaccination schedule for their farm. Do not use unregistered products that claim to be vaccines, they are illegal,” advises prof. Gareth Bath from the Small Stock Health Advisory Body.
The RVF virus is carried by mosquitoes and the appearance of the disease is ascribed to increased rainfall, which leads to an increase in mosquitoes. “As this outbreak occurred in the beginning of the winter season, it will probably be an isolated incident as the cold weather will result in a decrease in the number of mosquitoes and therefore decrease the risk the disease spreading. It must be noted that the risk will increase at the start of the summer season.
“This outbreak provides us with a useful warning that all cattle, sheep and goats have to be vaccinated to ensure that the level of immunity in the herds is high when the next summer season starts and the risk increases,” says DAFF in a media release.
RVF affects cattle, sheep and goats, and can be passed to humans. Farmers are advised to vaccinate their livestock. “Live vaccines can only be used in non-pregnant animals as the live vaccine can cause abortions. Only inactivated vaccines must be used in pregnant animals. Please take care when vaccines are administered after outbreaks have been detected. Use a clean needle for each animal as the virus can be spread between animals if the animals are in the incubation period. Animals in the incubation period will have a virus infection but will not show symptoms of the disease yet.”
If a person suspects that they might have been infected with RVF, they must consult a doctor.
RVF is a notifiable animal disease, but not a controlled animal disease, meaning that there are no prescribed control measures. The SA State Veterinary Services will give support and information to farmers in affected areas, but it is the responsibility of the animal owners to vaccinate their animals and prevent losses. Suspicion of disease must be immediately reported to the nearest State Veterinarian.