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==Description==

==Description==

Equine Infectious Anemia (EIA) is an exotic viral disease affecting horses, donkeys and mules characterised by immuned-mediated haemolytic anemia. It is caused by Equine Infectious Anemia 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 immuned-mediated haemolytic anemia. 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. EIA occurs in acute and subacute forms in susceptible horses but more commonly assumes a chronic course. Affected horses that recover from EIA may become lifelong carriers, and relapse of the disease may occur during times of stress or illness.

==Signalment==

==Signalment==

==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 when a nursing foal ingests milk from a carrier mare or iatrogenically via contaminated needles.

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 when a nursing foal ingests milk from a carrier mare or iatrogenically via contaminated needles.

 

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.

==Clinical signs==

==Clinical signs==

The incubation period of the disease ranges from 10 to over 45 days and the clinical presentation is highly variable. A large number of affected horses do not display any clinical signs. Animals may be affected acutely, chronically or sub-clinically and clinical signs vary according to the stage of the disease. Inapparent carriers may be clinically normal. In the acute stages, clinical signs may include mucosal petechial haemorrhages, depression, fever, lethargy and inappetance. Horses that have been infected for thirty days or may display the characteristic signs of EIA including ventral and limb oedema, anemia, icterus, 'spiking' fever and cachexia.

The incubation period of the disease ranges from 10 to over 45 days and the clinical presentation is highly variable. A large number of affected horses do not display any clinical signs. Animals may be affected acutely, chronically or sub-clinically and clinical signs vary according to the stage of the disease. Inapparent carriers may be clinically normal. In the acute stages, clinical signs may include mucosal petechial and ecchymotic haemorrhages, depression, lymphadenopathy, fever, lethargy and inappetance. Horses that have been infected for thirty days or may display the characteristic signs of EIA including ventral and limb oedema, anemia, icterus, pyrexia and cachexia.

==Diagnosis==

==Diagnosis==

The 'gold standard' for diagnostic confirmation is an agar gel immunodiffusion test (the Coggins test) which detects serum antibodies against the EIA virus. The test is 95% accurate for the diagnosis of EIA but false positives may be obtained from foals that have absorbed colostrum from affected mares and false negatives may occur during acute stages of EIA. The Coggins test may be performed in combination with an ELISA in order to increase the test sensitivity.  

The 'gold standard' for diagnostic confirmation is an agar gel immunodiffusion test (the Coggins test) which detects serum antibodies against the EIA virus. The test is 95% accurate for the diagnosis of EIA but false positives may be obtained from foals that have absorbed colostrum from affected mares and false negatives may occur during acute stages of EIA. The Coggins test may be performed in combination with an ELISA in order to increase the test sensitivity.  

==Treatment==

==Treatment==