African horse sickness (AHS) is a highly fatal, non-contagious, infectious disease, of horses, mules and donkeys caused by the AHS virus. Wageningen Bioveterinary Research conducts research on this disease.
This orbivirus is transmitted between hosts by small biting insects known as "midges" (Culicoides species). The clinical signs are usually more severe in horses than other equids and may vary depending on what form of the disease is present.
Zebras may be infected with AHS virus but do not exhibit clinical signs. Carnivores such as dogs and big cats can also be infected with AHSV after eating infected meat. And AHSV antibodies have been found in elephants and rhinoceros. But the importance of these species for the transmission of the virus remains unclear.
The virus exists as nine serotypes, all of which are endemic in sub-Saharan Africa. Outbreaks of African horse sickness have occurred as far north as Spain and Portugal and as far east as India and Pakistan, but it has not persisted in these regions. Recent outbreaks of AHS in Spain and Portugal were probably related to imports of infected zebras from southern Africa.
Spread of African horse sickness
The disease may be spread via the movement of infected equids but transmission is also promoted by climatic conditions which favour high populations of carrier insects (vectors). These insects can also be spread over long distances by wind dispersal.
Comparing Culicoides biting rates in horses and cattle in The Netherlands : potential relevance to African horse sickness epidemiology
Diagnostic DIVA tests accompanying the Disabled Infectious Single Animal (DISA) vaccine platform for African horse sickness
African horse sickness virus (AHSV) with a deletion of 77 amino acids in NS3/NS3a protein is not virulent and a safe promising AHS Disabled Infectious Single Animal (DISA) vaccine platform
Diel activity and preferred landing sites in Culicoides biting midges attacking Fjord horses
Quantitative analysis of the probability of introducing equine encephalosis virus (EEV) into The Netherlands
Requirements and comparative analysis of reverse genetics for bluetongue virus (BTV) and African horse sickness virus (AHSV)
Landing sites and diel activity in Culicoides midges attacking Fjord horses in the Netherlands
Faverjon, C., Leblond, A., Hendrikx, P., Balenghien, T., de Vos, C. J., Fischer, E. A., de Koeijer, A. A. 2015. A spatiotemporal model to assess the introduction risk of African horse sickness by import of animals and vectors in France. BMC Vet. Res. 11: 127.
van de Water, S. G., van Gennip, R. G., Potgieter, C. A., Wright, I. M., van Rijn, P. A. 2015. VP2 exchange and NS3/NS3a deletion in African horsesickness virus (AHSV) towards AHS Disabled Infectious Single Animal (DISA) vaccine candidates. J. Virol. 89: 8764-8772.
Yuta Kanai; Piet A. van Rijn; Mieke Maris-Veldhuis; Yuki Kaname; T.N. Athmaram; Polly Roya. 2014. Immunogenicity of recombinant VP2 proteins of all nine serotypes of African horse sickness virus. Vaccine 32: 4932–4937