Infectious disease caused by a Lentivirus and transmitted by biting insects that transfer blood from an infected horse to an uninfected horse.

It´s characterised by recurrent episodes of fever, anaemia, thrombocytopenia, loss of appetite, depression, rapid loss of weight, oedema of the lower parts of the body, incoordination and abortions.

As the disease becomes more chronic, yellow discolouration of the mucous membranes will develop with small haemorrhages, petechiaes. Approximately 50% of all affected animals die.

In others, apparent recovery occurs although the virus is never cleared from the body. Some infected horses remain symptomless, although remaining potential sources of infection for uninfected horses.

The disease is mostly seen in the warmer months and in areas where insect populations are high. It´s very important that horses used for donating blood for blood transfusions and for hyperimmune plasma transfusions are tested negative for EIA before they are used.

Infection can spread from a mare to her foal either in utero across the placenta, or via her colostrum or milk. The cELISA test is the most sensitive, rapid and cost-effective test which is now more appropriately used for the routine screening of symptomless EIA negative horses.

There is no specific treatment available for EIA neither there is a vaccine.

This article is based in scientific veterinary literature.