African Horse Sickness - Epidemiology

Epidemiology

AHSV was first recorded south of the Sahara Desert in the mid-1600s with the introduction of horses to southern Africa. The virus is considered endemic to the equatorial, eastern, and southern regions of Africa. Several outbreaks have occurred in Equidaes throughout Africa and elsewhere. AHS is known to be endemic in Sub-Saharan Africa, and has spread to Morocco, the Middle East, India and Pakistan. More recently, outbreaks have been reported in the Iberian Peninsula. AHS has never been reported in the Americas, eastern Asia or Australasia. 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 non-endemic areas.