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Understanding Equine Infectious Anemia (EIA)

Understanding The Threat of EIA

Equine Infectious Anemia (EIA), also known as Swamp Fever, is an infectious disease of horses, donkeys and mules caused by a virus. Horses infected with the EIA virus carry it for life. Most infected horses show no symptoms but they remain infectious, endangering the health of other horses. The best protection against EIA is to understand the disease and the control measures that can help keep your horses from contracting it.

What is EIA?

EIA is a viral disease that affects the horse’s immune system. The virus reproduces in the horse’s blood cells and circulates throughout the body. The horse’s immune system produces antibodies, which attack and destroy its own blood cell components. The result is anemia and organ-damaging inflammation. The clinical symptoms of EIA are variable and include fever, anorexia, depression, swelling of the underside of the belly and legs, muscle weakness and wasting, jaundice of mucous membranes and infertility. EIA can leave a horse vulnerable to other potentially fatal diseases.

EIA has three phases:

  • Acute - during this phase the virus is active, multiplying and harming the immune system. The acutely ill horse has heavy concentrations of the virus in its bloodstream.
  • Chronic - the animal has high concentrations of the virus in its blood but may alternate between remission and disease states.
  • Inapparent Carrier- the horse carries the virus but shows no apparent signs of illness. Stress or disease may trigger an acute episode.

At this time, there is no treatment or cure for a horse that has contracted EIA. There is also no vaccine available to protect a horse from the EIA virus.

Transmission

EIA is a blood-borne disease transmitted mainly through the natural feeding of large biting insects, principally horseflies and deerflies. Transmission can also occur through the re-use of contaminated needles and surgical and dental instruments. Because these processes can be identified, decisions can be made regarding disease management and control.

It is important to remember the threat that an EIA infected horse poses to the whole community. The risk may be unknown, but the consequences can be great, extending even to legal liability. Strict control measures should be followed in order to prevent the spread of this virus. All stables, farms, horse shows, racetracks, rodeos, clinics and equine event operators are strongly encouraged to ask for and verify a current Coggins certificate for all horses entering their premises. This, along with good management practices, will help in the fight against this disease.