A devastating disease that has been killing horses in Africa for hundreds of years could be held at bay in Sudan thanks to a vaccine made in Dubai.
The jab against African horse sickness (AHS), developed by Dubai’s Central Veterinary Research Laboratory (CVRL), is set to be used in Sudan from next week.
A longstanding problem in the North African country, AHS causes horses immense suffering and has a notable economic impact on poorer communities reliant on the animals.
The CVRL has sent 500 doses to Sudan, which will be used on racing and showjumping horses, according to Yousif Nageeb, from the Sudanese Horse Racing Federation.
Horse racing has a long tradition in Sudan and equines are especially important to some ethnic groups in the country’s western Darfur region.
But donations are needed to fund a wider vaccination programme of horses used in the country’s poorer communities, said Mr Nageeb.
“We’re looking for a sponsor to help us vaccinate all our equines, because there are poor people from Darfur and, even in the remote areas, horses are very essential for their life,” he said.
“We’ve had this pandemic for a long time and we’re losing lots of horses every year, from foals to fillies. Even the top ones we’re losing them because of African horse sickness.”
The CVRL's vaccine has been used in Kenya for several years and Dr Ulrich Wernery, the centre’s scientific director, said it has been credited with reducing the disease’s prevalence there.
“The amount of outbreaks has reduced dramatically in Kenya in many years because, we think, of the use of the vaccine,” said Dr Wernery.
How does the disease affect horses?
AHS is caused by an Orbivirus comprising nine serotypes (forms that produce a distinct response from the immune system) transmitted between animals by blood-sucking midges.
Described by Dr Wernery as “a dreadful disease”, it kills as many as 90 per cent of the horses it infects, about half of mules and around 10 per cent of donkeys. Zebras can also be infected but do not fall ill.
Clinical signs include difficulty breathing and a frothy discharge from the nose and mouth, oedema (watery fluid accumulation) of the head, congestion of the lungs and heart failure.
First identified almost 800 years ago, AHS remains endemic in sub-Saharan Africa and has also killed hundreds of thousands of horses during outbreaks in South Asia.
Worryingly, the disease was detected in south-east Asia for the first time last year, killing hundreds of horses, and the CVRL hopes its vaccine could be deployed there too.
AHS has never been detected in the Emirates, but the centre keeps frozen vaccine stocks in case of an emergency, which could happen as the midge is present.
“We get horses in the UAE and Dubai from all over the world, including from South Africa, where they regularly have outbreaks,” said Dr Wernery.
How is the vaccine made?
The CVRL vaccine contains an inactivated version of the AHS virus, mirroring some widely used Covid-19 vaccines, including those from Sinovac and Sinopharm, made using inactivated coronavirus particles.
With these vaccines, virus particles are grown under controlled conditions and inactivated by heat or chemicals so that they can no longer multiply or cause disease.
Production of the vaccine was supported, Dr Wernery said, by Sheikh Mohammed bin Rashid, Vice President and Ruler of Dubai, and Dr Ali Al Hashimi, the CVRL’s director general.
“We were very fortunate to isolate all nine AHS serotypes from Kenyan horse fatalities and it took 18 years to have them all,” said Dr Joseph.
“And since our vaccine contains all nine serotypes, the vaccine preparation is extensive.”
In another echo of coronavirus vaccines, CVRL’s shot is given as two injections at separate times to ensure maximum immunity, followed by an annual booster.
A different AHS vaccine developed in South Africa uses attenuated virus particles, which are weakened but can still replicate, but in rare cases attenuated viruses can become virulent again, which Dr Wernery said was a drawback of the South African vaccine.
However, he added that the South African vaccine had prevented many outbreaks and an ideal scenario was to use it alongside their shot to maximise protection.