A research team led by a Kenyan scientist has produced the first Rift Valley Fever (RVF) vaccine that can be used by both humans and animals.
In a study published this week in Scientific Reports, an online journal, the researchers demonstrated that a single injection with this vaccine is safe and offers complete protection against RVF in livestock and recommends that the vaccine be tried in humans.
RVF was discovered in Rift Valley in 1930, hence the name. It is caused by a virus that is transmitted by many different types of mosquitoes. However, the day-biting, black and white stripped, Aedes mosquito, is thought to be the main culprit. The virus kills young animals and causes pregnant livestock to abort.
Humans can get the virus directly through handling infected animal secretions (milk, blood) or through bites from mosquitos. In humans, the disease is clinically difficult to differentiate from malaria and can leave patients with impaired vision and causes deaths.
The Kenyan scientist leading this research is Dr George Warimwe (right), who is now currently based at The Jenner Institute, University of Oxford.
Dr Warimwe designed the vaccine using the same technology that is being used to develop several other human vaccines against diseases such as malaria, HIV and more recently Ebola. This technology, that uses the chimpanzee adenovirus vaccine vector, has been known to be safe in humans.
Currently, there is no human vaccine for RVF. However, there is a licensed RVF vaccine known as Smithburn® which is produced at the Kenya Veterinary Vaccines Production Institute (KEVEVAPI) and is widely used in Africa. However, Smithburn® carries the risk of inducing abortions in animals and some animals that are vaccinated still succumb to the disease when exposed to the virus.
This new vaccine developed will be safer on animals and also has the potential to work in humans.
Dr Warimwe got funding from the Wellcome Trust, Gates Foundation and University of Oxford to conduct his research.
For this vaccine to be registered for use in animals, it will need to undergo larger trials in different populations of animals in different parts of the East African region where the disease is common. Once the vaccine proves to be safe and effective in these larger trials, it will then be licensed for use in the region.
Dr Warimwe says trials will in two years begin in people living within regions in East Africa where the disease wrecks havoc.
Dr Eric Osoro, head of the Zoonotic Disease Unit at the Ministry of Health in Kenya, welcomed the prospect of being able to control RVF in the near future.
“This is an exciting study conducted in Kenya towards vaccine development against RVF, a life threatening disease in both humans and animals. An effective vaccine will be the cheapest way of controlling this disease,’ said Dr Osoro.
To appreciate the impact that this vaccine will have, one will need to look at the outcome of the RVF outbreak in Kenya that started in November 2006 through to March 2007. This was precipitated by heavy rainfall and flooding in the then North-Eastern Province.
Researchers Karl Rich and Francis Wanyoike estimate that the RVF induced losses of over Sh2.1 billion (US$32 million) on the Kenyan economy between 2006 and 2007.