Rift Valley Fever (RVF) is an acute viral hemorrhagic fever that causes illness in animals (such as cattle, buffalo, sheep, goats, and camels). RVF is a zoonosis, meaning that people can also become infected, mainly by handling sick or dead animals.

Based on recent research from a group of international researchers it, however, seems as if RVF infections in humans are more likely to come from mosquitoes than cattle Rift Valley Fever occurs after a five to 10-year drought. Looking at the drought many areas in South Africa have suffered for the past five years it is anticipating that a fatal fever might hit livestock, also putting humans at risk.

Fortunately only a small percentage (around 10%) of people infected with this disease develop severe symptoms, including eye disease, excessive bleeding, and swelling of the brain. The recovery rate for humans are good with 1% deaths recorded. The last case was reported during 2018 in Jacobsdal, Free State Province. All this said, it is severe and consequently a Notifiable disease. Based on reports from Colombia University El Nino, LA Nina Southern Oscillation (ENSO) forecast where they predict a strong La Nina phenomenon through our rainy season and a neutral sea temperature during our coming winter.

We have already experienced the joys of good rains, almost countrywide, with the Free State particularly wet and lush. These conditions are ideal for flooding and the formation of pans of water in which the Aedes mosquitoes, responsible for the transmission of the RVF, virus breed and multiply.

The only ways to prevent the disease spreading and infecting livestock are to vaccinate our livestock and to prevent mosquito bites, using products that are registered for the control of mosquitoes (usually deltamethrin containing dips, sprays and pour-ons). Clearly, an annual vaccination against the disease is the most effective and easiest route.

Onderstepoort Biological products produce, currently two vaccines, viz. 1. OBP Live RVF vaccine containing the Smithburn stain. Although it is believed that this vaccine gives protection of longer duration, it is still recommended that all animals should be vaccinated annually. This vaccine should, however, not be used in pregnant animals. 2. OBP killed RVF vaccine, which needs annual vaccination and is safe to use in pregnant animals.

It, however, requires two initial doses 6 weeks apart making it more expensive and labour intensive to administer. Ideally, vaccination should have already been carried out in early spring, but it is not yet too late. Time is now, however of the essence as most outbreaks begin mid-to late Summer. Do yourself and the country a good turn for new year, vaccinate your stock against Rift Valley fever as soon as physically possible.

Source: Afrivet