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==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. 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.  

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==

==Pathogenesis==

==Pathogenesis==

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 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. 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.

The incubation period of the disease ranges from 10 to over 45 days and the clinical presentation is highly variable. EIA occurs in acute and subacute forms in susceptible animals but more commonly assumes a chronic course. However, a large number of affected horses do not display any clinical signs and inapparent carriers may be clinically normal.  

The incubation period of the disease ranges from 10 to over 45 days and the clinical presentation is highly variable. EIA occurs in acute and subacute forms in susceptible animals but more commonly assumes a chronic course. However, a large number of affected horses do not display any clinical signs and 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.

In the acute stages, clinical signs may include mucosal petechial and ecchymotic haemorrhages, depression, lymphadenopathy, fever, lethargy and inappetance. In rare cases the disease may result in sudden death. Horses that have been infected for thirty days or may display the characteristic signs of EIA including ventral and limb oedema, anemia, bloody diarrhoea, icterus, pyrexia and cachexia.

==Diagnosis==

==Diagnosis==

==Treatment==

==Treatment==

No specific treatment or vaccine for EIA is available and treatment is usually supportive. Infected horses should be isolated from other horses due to the risk of spread of disease. NSAIDs may be used to control pyrexia and inflammation and/. Corticosteroids are contraindicated due to the possibility of exacerbating viral replication and clinical disease. In the UK, DEFRA policy is that horses with a confirmed (tested) case of EIA must be slaughtered under Section 32 of the Animal Health Act 1981. Horses that have been in close contact with diseased animals must be kept in isolation for 90 days and tested on a monthly basis with regular veterinary assessment. After this period of testing, restrictions may be lifted if no disease is found.

No specific treatment or vaccine for EIA is available and strict procedures for affected horses are enforced in the UK. Any horse that is suspected to be infected with EIA must be reported to the appropriate divisional veterinary manager of DEFRA. DEFRA policy is that horses with confirmed (tested) EIA must be slaughtered under Section 32 of the Animal Health Act 1981. Horses that have been in close contact with diseased animals must be kept in isolation for 90 days and tested on a monthly basis with regular veterinary assessment. After this period of testing, restrictions may be lifted if no disease is found.

==Control==

==Control==

Although attenuated live vaccines are available in the United States, these are not in current use in the UK.  

Although attenuated live vaccines are available in the United States, these are not in current use in the UK. Acutely affected horses carry high levels of virus in the blood and are a high risk source of infection to other horses so should be isolated immediately if EIA is suspected. All movement of horses on and off the premises must be prevented.

==Prognosis==

==Prognosis==

Foals exposed to EIAV have a high fatality rate but generally horses recover from the disease, becoming lifelong inapparent carriers. Although occasionally some horses die from EIA, the majority become lifelong inapparent carriers.

Foals exposed to EIAV have a high fatality rate but generally horses recover from the disease, becoming lifelong inapparent carriers. Affected horses that recover from EIA may become lifelong carriers, and relapse of the disease may occur during times of stress or illness. The current UK control measures in the UK

 

==References==

==References==