Equine Infectious Anaemia: What It Is And How Testing Works

Equine infectious anaemia (EIA) is a viral disease of horses and other equids. Infection is lifelong, and the sources reviewed describe no cure and no vaccine in the United States. Blood tests that look for antibodies are the standard way to find it.

How the virus spreads

The agent is a lentivirus that affects equids only. It moves mainly through blood. Biting flies can carry it mechanically between animals, and needles, syringes or instruments contaminated with blood can do the same. UC Davis also lists mare-to-foal spread before birth, through milk, or through semen as less common routes.

What infection looks like

Many infected horses show no signs. When signs do appear, UC Davis describes a short fever with lethargy, then recurring fever, severe anaemia, poor appetite, jaundice, limb swelling and nosebleeds, with sudden death possible. Survivors can relapse at times of stress. Reported incubation varies by source: UC Davis gives 15 to more than 45 days, while WOAH gives one to three weeks and says it may reach three months. A carrier can look healthy, so testing is the only reliable check.

How testing works

Two antibody tests are in common use. The agar gel immunodiffusion test, often called the Coggins test, detects antibodies two to three weeks after infection, according to UC Davis. The ELISA detects antibodies earlier and is more sensitive, but it gives more false positives. WOAH says positive ELISA results are confirmed with the agar gel test. A horse tested very early in infection can read negative, so a repeat test may be needed. PCR can support serology in particular situations.

Foals need care. Antibodies passed in colostrum can often be detected for up to 12 months, so a positive young foal does not always mean infection. Sequential testing helps, and a veterinarian interprets it.

What a positive result means

An infected horse can pass the virus to others. The US sources describe lifelong separation of at least 200 yards from other horses, or euthanasia. Rules differ between countries, so local veterinary authorities decide what applies. I did not find prevalence data for EIA in Nigerian or Sahel horses in the sources retrieved, so the local picture is unknown.

What this means for the programme

Mares and ponies are screened for equine infectious anaemia, and for trypanosomiasis, before breeding or sale. A veterinarian signs off, and a written start record is kept. The programme is in formation. No ponies are for sale, and no results are claimed yet.

Frequently asked questions

Can EIA be treated? The sources reviewed state there is no treatment or cure, and no vaccine in the United States.

Does a negative test last forever? No. It shows antibody status on the test date. Early infection can be missed, so a veterinarian decides when to retest.

Is EIA a risk to people? None of the sources retrieved described it as a human health concern. It is a disease of equids.