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WBFSH Seminar - Alan Guthrie
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Alan Gutherie (Photo: Ridehesten.com).
AFRICAN HORSE SICKNESS
African horse sickness (AHS) is a non-contagious, insect-transmitted disease of equids. In
horses, the disease is usually peracute to acute and in naive animals more than 90% of those
affected die. Mules are less susceptible than horses and African donkeys and zebras rarely
show clinical signs of disease. The first known historical reference to a disease resembling
AHS was reported in Yemen in 1327. Neither horses nor donkeys were indigenous to
southern Africa but were introduced shortly after the arrival of the first settlers of the Dutch
East India Company in the Cape of Good Hope in 1652. Dutch East India Company records
make frequent reference to “perreziekte” or “pardeziekte” in the Cape of Good Hope
including an outbreak in 1719 during which about 1,700 horses died of AHS. AHS has
subsequently been recognized in other parts of sub-Saharan Africa where AHSV is
considered to be endemic. There have been a number of AHS epidemics outside of the
normal endemic area. These include outbreaks in North Africa, Europe, the Middle and Near
East.
The recent expansion of Bluetongue, a viral infection of ruminants which is closely
related to AHS, into Europe has been associated with climate change. This, along with some
changes in the epidemiology of AHS in the endemic areas has resulted in a heightened
awareness of AHS in parts of the world that are currently free of the disease. The European
Union has been proactive in that it has introduced legislation to establish reference
laboratories and contingency plans for AHS in Member States. Furthermore, the EU is
currently in the process of establishing a vaccine bank for AHS.
Highly sensitive and specific virus detection (qPCR) assays are now more widely
available to confirm the presence or absence of AHSV infection in equids. These tests allow
for the rapid detection of cases of AHS. The World Organisation of Animal Health has
established guidelines for the safe import of animals from AHS infected areas which, if
applied, mean that animals can be imported with negligible risk.
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