Equine Infectious Anemia (EIA)

Disease Basics

EIA (or Swamp Fever) is an infectious and potentially fatal viral disease of horses usually transmitted from horse to horse by large biting insects such as horseflies and deerflies.  Needs and equipment contaminated with blood from an infected horse can also spread the virus when used on unexposed horses.  No vaccine or treatment exists for the disease.  Some equines can be infected with the virus and act as carriers, but don’t show any signs.  It is a reportable and actionable disease.  


Minimizing or eliminating contact between non-exposed horses and the secretions, excretions, and blood of infected horses can help control the spread.  Insect control is another method for preventing the transmission of the virus.

Clinical Si​​​gns of Illness

Horses that are infected with the virus experience fever, weight loss, yellowing of body tissues, anemia, swelling in the limbs and weakness.  


The Coggins test, or agar-gel immunodiffusion test, is internationally recognized as the standard to which all other tests are compared for diagnosing EIA.  

Huma​​n Health

There is no known human health impact caused by EIA.