Changes

==Pathogenesis==

==Pathogenesis==

EIA occurs worldwide but most commonly in countries with warm climates. The virus is usually transmitted via mechanical innoculation of blood from large biting flies such as horseflies (''Tabanid'' spp) or stable flies (''Stomoxys calcitrans''). Transmission of the virus can also occur through saliva, milk, body secretions or via contaminated needles and blood products. The disease may be passed from pregnant mares to their foals across the placenta.

EIA occurs worldwide but most commonly in countries with warm climates. The virus is usually transmitted via mechanical innoculation of blood from large biting flies such as horseflies (''Tabanid'' spp) or stable flies (''Stomoxys calcitrans''). Additionally, transmission of the virus may occur through saliva, milk, body secretions or via contaminated needles and blood products. The virus may also be passed from pregnant mares to their foals across the placenta.

Following coating of erthrocytes and thrombocytes by the virus and the development of a Type III immune complex reacion, lysis of erthrocytes occur. Infection with EIA results in an acute phase of infection followed by recurrent episodes that usually susbide after a period of time. Affected horses become persistently infected, lifelong carriers of the disease due to latent infection of macrophages. EIA may be induced by stress, disease or immunosuppressive drugs.

Following coating of erthrocytes and thrombocytes by the virus and the development of a Type III immune complex reacion, lysis of erthrocytes occur. Affected horses become persistently infected, lifelong carriers of the disease due to latent infection of macrophages. EIA may be induced by stress, disease or immunosuppressive drugs.

==Clinical signs==

==Clinical signs==