The Central Veterinary Institute of Wageningen UR (CVI) and the Faculty of Veterinary Medicine of Utrecht University are jointly developing modern vaccines against Rift Valley fever. This viral disease, which is prevalent especially in Africa but is moving to the north, can cause serious symptoms in both animals and people, and can even be fatal. New vaccines, which are used for mass vaccinations of animals, can bring this threat for people and animals to a halt. This was the conclusion of the inaugural address given by Rob Moormann on 9 June at the Faculty of Veterinary Medicine of Utrecht University. Rob Moormann is also a virologist at the Central Veterinary Institute of Wageningen UR. He has many years of experience in developing modern veterinary vaccines.
In recent years, there has been an increasing threat from exotic animal diseases that are transmitted by insects to people. Due to climate change, increasing tourism – especially to exotic destinations – and increasing worldwide trade (for example the trade in wild animals), there is an increased risk that pathogens will spread more quickly around the world. These exotic infectious diseases are a real threat to the health of our Western society, because effective prevention and control measures, such as vaccines, are often lacking.
A current example of such a virus disease that is transmitted by insects is the blue tongue virus, which was first introduced into the Netherlands in 2006. This disease is not hazardous for people. But there are still more animal diseases lurking in the world that are hazardous for people. These diseases include Dengue, Chikungunya, West-Nile, Rift Valley and Krim-Congo fever. To control and eliminate these diseases, vaccines are the only adequate answer, said Rob Moormann in his inaugural address. Therefore a special chair group in the vaccinology of viral zoonoses was established in Utrecht, where there is a great deal of expertise about viral processes. Moormann holds this chair. Together with the Central Veterinary Institute, where a great deal of expertise is available about the development of modern vaccines, this chair group will develop new vaccines. This specifically concerns DIVA vaccines with which infected animals can be distinguished from vaccinated animals by using a corresponding diagnostic test. The group will begin by developing vaccines against Rift Valley fever, especially because this disease can lead to illness and death of both animals and people.
Until recently, the Rift Valley virus was present only on the African continent. After 2000 the virus was also encountered in Saudi Arabia and Yemen. The Rift Valley virus can be transmitted between animals and to people by a broad range of mosquitoes, including the normal house mosquitoes Culex pipiens and Aedes Vexans. However, the most important transmission route of the Rift Valley virus to people is via direct contact with the blood, urine or organs of infected livestock. As a result, most cases of the disease occur among herdsmen, livestock farmers, slaughterhouse workers, veterinarians and hospital staff. The mortality percentage of people following infection with the Rift Valley virus is approximately 1%. Nevertheless, during epidemics in 2006 and 2007 in Kenya, Somalia and Sudan, hundreds of people died from the haemorrhagic fever that the virus causes.
No registered vaccines for human use are currently available for Rift Valley fever. In cattle, sheep, goats and camels, infection with the Rift Valley virus leads to abortion and death of young animals and causes serious economic damage in Africa, partly because the animals are the only source of income for many people. At the present time, a live vaccine is available for Rift Valley fever. However, this live vaccine is not safe and can cause abortion in pregnant animals. A deactivated vaccine is also available, but it is much less effective.