Changes

==Description==

==Description==

Equine Infectious Anaemia (EIA) is an exotic viral disease affecting horses, donkeys and mules. It is caused by Equine Infectious Anaemia Virus (EIAV), an equid-specific lentivirus in the retrovirus family that is closely to related to HIV in humans.  

Equine Infectious Anaemia (EIA) is an exotic viral disease affecting horses, donkeys and mules characterised by viraemia, anaemia and thrombocytopaenia. The disease is caused by Equine Infectious Anaemia Virus (EIAV), an equid-specific lentivirus in the retrovirus family that is closely to related to HIV in humans. Cases of EIA in the UK are extremely rare and have previously occurred in horses that have travelled abroad or been imported from areas of endemic disease. In the UK the disease is notifiable and confirmed cases must be humanely destroyed.

Cases of EIA in the UK are extremely rare and have previously occurred in horses that have travelled abroad or been imported from areas of endemic disease. In the UK the disease is notifiable and confirmed cases must be humanely destroyed.

==Signalment==

==Signalment==

EIA occurs worldwide but most commonly in countries with warm climates. The virus is usually transmitted via mechanical innoculation of blood via 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.

EIA occurs worldwide but most commonly in countries with warm climates. The virus is usually transmitted via mechanical innoculation of blood via 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. 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.

Viral replication occurs primarily in mature tissue macrophages located in the spleen. These macrophages act as the main source of high-titre viraemia during the course of the disease and also as a reservoir for infection during subclinical infection.

Infection in subclinically affected horses may be reactivated during times of stress, disease or during treatment with immunosuppressive drugs.

==Clinical signs==

==Clinical signs==