AHS virus was first recorded south of the Sahara Desert in the mid-1600s, with the introduction of horses to southern Africa.

[2] AHS is known to be endemic in sub-Saharan Africa, and has spread to Morocco, the Middle East, India, and Pakistan.

Epidemiology is dependent on host-vector interaction, where cyclic disease outbreaks coincide with high numbers of competent vectors.

The most important vector for AHS in endemic areas is the biting midge Culicoides imicola, which prefers warm, humid conditions.

Larvae do not carry the virus, and long, cold winters are sufficient to break epidemics in nonendemic areas.

[citation needed] The common hosts of this disease are horses, mules, donkeys, and zebras.

The clinically affected animal has trouble breathing, starts coughing frothy fluid from nostril and mouth, and shows signs of pulmonary edema within four days.

Additionally, edema is presented under the skin of the head and neck, most notably in swelling of the supraorbital fossae, palpebral conjunctiva, and intermandibular space.

Presumptive diagnosis is made by characteristic clinical signs, post mortem lesions, and presence of competent vectors.

[5] Infection was reported in Pak Chong district of Nakhon Ratchasima province in Thailand in March 2020 when 42 racehorses died from an unknown illness which was later confirmed to be African Horse Sickness virus serotype 1.