A new vaccine in the pipeline for African Horse Sickness is expected to make an important step forward, potentially opening up greater movement of horses from areas where the disease is endemic.
The new vaccine under development is said to have one crucial feature: It allows scientists to distinguish the immune response between a vaccinated horse and one that has been infected.
The virus that causes African Horse Sickness is carried by biting insects. It causes severe respiratory problems and about 90% of horses that catch it die within a week.
It is endemic to sub-Saharan Africa although there have also been known outbreaks in Spain and Portugal.
The biting midges that transmit the disease are found all across Europe and there is concern regarding the influence of climate change on midge populations.
Many affected countries in Africa currently use a “live” vaccine against the disease. These vaccines render pathogens harmless, vastly reducing their ability to infect a host. However, testing cannot distinguish between a horse mounting an immune response against the vaccine and a response against the naturally occurring virus.
They have also shown limitations in terms of safety and suitability for endemic situations. There are concerns that the attenuated vaccine virus may become infectious again due to mutations, causing African Horse Sickness in the host animal.
These shortcomings have severely curtailed horse movements from African countries to nations worried about the accidental importation of the disease.
The International Horse Sports Confederation (IHSC) describes the new candidate vaccine as a significant step.
Over the past three years, the IHSC has supported several research projects in collaboration with the World Organisation for Animal Health (OIE).
These projects have aimed to address critical equine health and disease issues, providing support for various scientific studies to develop or improve diagnosis tests or vaccines for diseases regarded as priority diseases that impede safe international horse movements.
An intensive project was supported to evaluate alternative vaccines for African Horse Sickness.
An expert IHSC working group says the candidate vaccine meets DIVA standards — Differentiation of Infected Animals from Vaccinated Animals.
The candidate is an inactivated multivalent vaccine against the disease.
The preliminary view of the IHSC Working Group is that it has the potential to be safe and efficacious, and may be used in endemic situations, as well as in outbreak situations in all ages and physiological groups.
The IHSC Working Group has assessed the potential market for the new vaccine and prepared a plan for its development. It proposes steps for the progression of the vaccine candidate’s development through to commercial production and effective future use.
This plan includes provisions for a challenge study, which is considered as a necessary next step in order to show the ability of the candidate vaccine’s effectiveness against all nine African Horse Sickness serotypes, and which will support regulatory registration of the vaccine.
The IHSC is talking with key stakeholders in South Africa in order to share the research work and expertise, and to assist the industry through the next phases of the candidate vaccine’s development.
Whilst emphasising the importance of industry support for the future success of any vaccine development, the IHSC will continue to provide technical guidance to the industry as required.
“The IHSC believes that the development and production of a new African Horse Sickness vaccine will be a major achievement, and will deliver a far-reaching positive impact on horse sports around the world,” its chairman, Louis Romanet, says.
He says he is proud of the research achievements through the collaboration between the IHSC and the OIE.
“Indeed, the identification of a potential AHS vaccine candidate through this collaboration highlights the real power of the public-private partnership between the peak international horse sports bodies and the OIE.”
The International Equestrian Federation (FEI) and the International Federation of Horseracing Authorities (IFHA) have assisted with time and resources in the development of an African Horse Sickness vaccine to this point.
“We now look forward to working with industry, particularly in South Africa, in order to seek to prove up the vaccine candidate, and hopefully work through to development, production, and widespread use,” Romanet says.
“That will require more investment and time. However, we are confident that a new vaccine would be transformative for horse movements in and out of South Africa, which have been impacted by African Horse Sickness for too long.”
The FEI’s veterinary director, Göran Akerström, says a new vaccine will also help to protect the world’s most valuable horse populations.
“It’s less than 30 years since African Horse Sickness was present in Spain, even threatening the Olympic Games in Barcelona.
“The midge vector of the virus is present in Europe, and if the virus were to enter Europe there would be a major risk of a rapid spread. A traceable safe vaccine already available in vaccine banks would be a very effective first line of defence.”