CPD Article | EQUINE
Acute presentation Cost considerations
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Rapid development of severe pulmonary edema.
Pyrexia (41°C/105.8°F).
Conjunctival infection.
Acute dyspnea.
Cough.
Early death (<12 h).
Geographic incidence
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Predominantly found in Africa, especially Sub-
Sahara region.
North and South Africa.
Egypt.
Morocco.
Pakistan/India.
Turkey/Cyprus.
Spain/Portugal.
Age predisposition
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None.
All ages can be affected.
Breed/Species predisposition
• All breeds of horse are highly susceptible.
• Mules/Hinnys.
• Donkeys.
• Zebras.
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Public health considerations
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Humans not natural hosts of the virus and no
evidence that humans can become infected with
field strains of AHS virus.
High fatality.
Restriction on international trade.
Pathogenesis
Etiology
• African Horse Sickness virus (AHSV) is a double-
stranded RNA Orbivirus in the family Reoviridae,
similar to Bluetongue virus (BTV) and epizootic
hemorrhagic disease virus (EHDV).
• There are 9 immunologically distinct serotypes:
○ ○ Serotype 9 is widespread in endemic areas and
is responsible for the majority of AHS outbreaks
outside Africa.
○ ○ Serotypes 1-8 are found in limited geographical
areas.
○ ○ Serotype 4 was involved in the outbreak in
Spain and Portugal in 1987-1990.
• Virus is transmitted by night-flying biting insects
primarily by Culicoides spp. It is possible that
mosquitoes and biting flies (Stomoxys and
Tabanus) may also be able to transmit although the
significance of this is probably low.
• Transmission cannot occur directly between
animals.
Predisposing factors
General
• Geographical area - endemic to sub-Saharan,
central and eastern Africa.
• Seasonal incidence following rains - late summer
and warm-events.
• Low-lying areas.
• Volume 21 Issue 4 | December 2019 •
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