What is EIA?

This disease is something most horse owners only know in relation to the test we use to identify the disease, aka Coggins test. That term is thrown around quite a bit but it surprises me how little people actually know about this disease. If you own horses then you should familiarize yourself with the ins and outs of EIA. Here are some relevant facts about EIA that you may not know.

EIA virus is closely related to the HIV-1 virus that causes AIDS in humans. The disease is transmitted by biting flies (usually the tabinus horse flies and deer flies), contaminated needles or surgical instruments, and blood transfusions. Once an animal is infected they are infected for life.

What does EIA look like?

Clinical disease can vary from sudden and severe to mild and unapparent. Signs of disease can include fever, anemia, yellow mucous membranes (icterus), ventral edema (swelling under the abdomen), weight loss, nose bleed (epistaxis), weakness (lethargy), and death. Other systems can be affected and contribute to other signs: hepatic (liver), cardiac (heart), neurological (brain and spine).

What is a Coggins Test?

There is no effective treatment or preventive measures (vaccinations) that are available at this time. The only control measures in place are to test animals for the disease and limit movement and exposure. This is the part that most horse people know: the test for EIA is called a Coggins test. This test got its name from person that developed the test, Dr. Leroy Coggins. Dr. Coggins developed an agar gel immunodiffusion (AGID) test in 1970. Another variation on the Coggins test that was later developed is the enzyme-linked immunodifusion assay or ELISA test. Since the advent of the Coggins test and appropriate control measures, the horse industry has been able to reduce the number of positive cases from over 300 in 1980 to just 37 in 2009. However, the numbers have started to go back up from those 37 cases in 2009 to 82 in 2011. Most of the cases found in the United States are along the “hot zone” which consists of the Mississippi River corridor and along the coast from the Gulf coast states to the Mid Atlantic.

In an effort to control this disease, the USDA and state departments of agriculture have placed restrictions on the movement and sale of all equine to those testing negative for EIA within the past 6-12 months. Most states require all equine owners to show proof of a negative test report in order to travel. Only Category II Accredited veterinarians are authorized to pull blood and submit for EIA testing and only certain USDA approved labs are able to perform these tests.