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Also known as: EIA, Swamp Fever
Description
Equine Infectious Anemia (EIA) is an exotic viral disease affecting horses, donkeys and mules. It is caused by an equid-specific lentivirus in the retrovirus family,http://wikivet.net/index.php?title=Equine_Infectious_Anemia&action=edit Equine Infectious Anemia Virus (EIAV). The virus is usually transmitted through large biting flies such as horseflies (Tabanid spp) or stable flies (Stomoxys calcitrans). Transmission occurs when these species of flies are in proximity to horses
Pathogenesis
- Virus coats red blood cells and thrombocytes
- Type III Immune complex disease develops
- Non-neutralizing antibody and complement lyse RBC's, causing:
- Jaundice
- Vasculitis
- Hemorrhage
- Diarrhoea
- Loss of condition
- Oedema
- High mortality
Epidemiology
- Notifiable in UK but endemic in parts of the US
- Animals can be carriers for years despite being antibody-positive
- Transfer is mechanical via vectors:
- Mosquitoes transfer infected macrophages
- Also transferred via infected needles, semen and milk
- Infected horses have lifetime latent infection of macrophages with recurring bouts of virus when immunocompromised
Clinical signs
The incubation period of the disease ranges from 10 to over 45 days and initial clinical signs may be vague or unnoticed. Infection may only be detected following serological testing. Owners of affected animals may Animals may be affected acutely, chronically or sub-clinically.
Diagnosis
- Coggins test required for horse movement in the US:
- Serum antibody by immunodiffusion in infected horse spleen
Control
- Slaughter of infected animal
- 2 clear Coggins tests of all horses before movement allowed
- Vector control: stabling, etc.