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South African horse owners are once again entering African horse sickness (AHS) season with a shortage of vaccines according to role players in the industry. Waiting lists at animal hospitals and equestrians unable to compete due to the lack of vaccines are slowly becoming the new norm as Onderstepoort Biological Products (OBP) struggles to meet the demand.
OBP representatives say that they have been distributing the AHS vaccine for the past few weeks and are continuing to do so. They claim that the vaccines will be sufficient for this season and anticipate more availability in September 2024. However, Dr Evert Olivier, a veterinarian at Bapsfontein Animal Hospital, shares his concerns about the lack of vaccines provided by OBP: “Availability of the AHS and other vaccines from OBP is a big problem”. Olivier explains that their vaccine supply is low, and clients must be placed on a waiting list if they want vaccines for their horses.
Read more about the confirmed Eastern Cape AHS outbreak here.
Glynn Catton, an industrial veterinary consultant and owner of Stride Distributors says there is a “major dilemma” concerning the lack of AHS vaccines in South Africa. According to Catton, Namibia did not receive vaccines last season and subsequently cannot compete in equestrian sport in South Africa. Dr Sheelagh Higgerty, from the South African Equestrian Federation and national head veterinarian for the International Federation for Equestrian Sports, confirms that unvaccinated horses cannot compete. She says that despite the vaccine scarcity, equestrian events in South Africa are proceeding normally this season as there is no “epidemic of deaths”. Event cancellations depend on localised outbreaks.
Design Biologix is in the process of developing a new AHS vaccine but will not be able to assist horse owners this season. “We are developing one, but are still far from finished,” said Angela Buys, CEO of Design Biologix. The company actively monitors virus strains. Dr Otto Koekemoer, R&D manager at Design Biologix, explains that although the AHS virus genome undergoes continuous changes, there is no formation of new serotypes. Therefore, the effectiveness of new vaccines is still being tested for their ability to neutralise viruses of the known serotypes.
What is AHS?
AHS is a life-threatening haemorrhagic disease that affects horses, zebras and donkeys. It is transmitted by midges (Culicoides spp.) and occurs from November to May, with the highest incidence from February to April. There are three forms of the virus: pulmonary, cardiac and acute.
According to Dr Camilla Weyer, senior research officer and AHS control manager at South African Equine Health and Protocols (SAEHP), the pulmonary form, also known as ‘Dunkop’, has the highest fatality rate of 95%. Infected horses exhibit symptoms such as a high fever of 39 to 40°C, trouble breathing and large amounts of frothy, serofibrinous fluid coming out of their nostrils. Horses can die from respiratory failure within 24 hours after being infected.
The cardiac form, known as ‘Dikkop’, gives the appearance of a swollen head with fever and mucous membrane congestion as initial symptoms. The acute form combines features of both pulmonary and cardiac forms, which means the horse may suffer from lung issues and swelling.
Direct export of horses reinstated
Despite the lack of vaccines, the direct export of registered horses from South Africa to Europe was recently reinstated. Adrian Todd, managing director at SAEHP, says: “The principles of the control measures for AHS that are required in South Africa are laid out in the European Union (EU) legislation, governing export conditions. Any lack of vaccination does not put these protocols at risk in the immediate future”. Todd says that if an outbreak does occur within the AHS-controlled area in the Western Cape, it can result in the suspension of the export status by the EU as was the case in 2011.
Therefore, South Africa is obliged to report all cases of AHS within the controlled area to trading partners and the World Organisation for Animal Health. Todd states that the last cases in the AHS-controlled area occurred in 2021 in the Cederberg area. Generally, between 300 to 600 cases of AHS are reported annually in South Africa. The last time that more than 600 cases were registered was in 2013. Since 1993 the general trend for AHS cases revealed an annual decline. – Olga-Louise Lemmer, Plaas Media.
