The virus which causes EVA was first isolated in 1953, but the disease has afflicted equine animals worldwide for centuries.

[6] Following infection, the first sign is fever,[7] peaking at 41 °C (106 °F),[8] followed by various signs such as lethargy,[7] nasal discharge,[8] "pink eye" (conjunctivitis),[7] swelling over the eye (supraorbital edema),[7] urticaria,[4] and swelling of the limbs and under the belly (the ventral abdomen) which may extend to the udder in mares or the scrotum of male horses.

[8] More unusual signs include spontaneous abortion in pregnant mares, and, most likely in foals,[8] severe respiratory distress and death.

Arteriviruses are small, enveloped, animal viruses with an icosahedral core containing a positive-sense RNA genome.

[10] The virus causing EVA was first identified following an outbreak of respiratory disease and spontaneous abortion on a horse farm in Ohio in 1953.