AffectedAnimals:
All equids, including horses, ponies, mules, donkeys, and zebras are susceptible to infection with EIAV. There are no age, sex, or breed predilections. Donkeys may experience less severe disease than other equids.

Overview:
Equine infectious anemia, or EIA, is an infectious disease of horses and other equids caused by the equine infectious anemia virus, or EIAV. The disease has a worldwide distribution. In the United States, the true incidence is unknown since only about 20 percent of the total U.S. horse population is routinely tested. Of those horses tested in 1999, only 0.06 percent were infected. The incidence is higher in the Gulf Coast states, as the climate is favorable for virus transmission. The virus is transmitted primarily by blood-feeding horseflies and deerflies.

Infection with EIAV results in recurring, cyclic episodes of fever, lethargy, thrombocytopenia, or low platelets, anemia, and in some cases, weight loss, ventral edema, petechiation, or pinpoint bleeding in the skin, hemorrhage, and death. Most horses' immune systems control the infection within a year, and thereafter show no clinical signs of disease. However, these horses will remain lifelong inapparent carriers of the virus. These otherwise normal-appearing horses are capable of transmitting the virus to uninfected horses primarily through biological vectors.

Diagnosis is primarily based on clinical signs and the result of serologic testing, using the AGID, or Coggins test, or the C-ELISA test for antibodies against EIAV. There is no specific treatment for EIA. The disease is reportable in the United States, and federal law prohibits interstate travel of infected animals, except for slaughter, return to place of origin, or transport to a recognized research facility or diagnostic laboratory.