Equine infectious anaemia

Equine infectious anaemia is category 1 restricted matter.

Under Queensland legislation, if you suspect the presence of this disease in any species of animal, you must report it to Biosecurity Queensland on 13 25 23 or contact the Emergency Disease Watch Hotline on 1800 675 888.

Equine infectious anaemia (EIA) is a noncontagious, infectious viral disease of horses and other equidae.

Cause

A. Lentivirus

Distribution in Queensland

In Queensland, it mainly occurs along the major river systems, but individual cases can be found in any area due to the movement of symptomless carrier horses.

The disease has been detected worldwide.

Life cycle

The incubation period is 2-4 weeks. Once the animal is infected, it will carry the virus for life.

Affected animals

horses

Hosts

Horses

Symptoms

The clinical findings and course of EIA are variable, depending on the virulence of the virus strain, viral dose, and susceptibility of the horse.

The disease can be acute, with symptoms including:

  • deep depression
  • rapid loss of condition
  • generalised weakness
  • fever (up to 41ºC), and
  • a clear nasal discharge.

Anaemia develops as the disease progresses and pale mucous membranes, petechial haemorrhages and jaundice are seen. Oedema of the brisket, ventral abdomen and limbs occurs. Dragging of the hind limbs is seen. Other signs such as diarrhoea, dysentery and abortion may occur at later stages of the disease. Some horses may have periods of normality alternating with acute episodes of illness. Occasionally animals can appear normal even though they are infected and test serologically positive.

How it is spread

When a horse is clinically ill, all bodily discharges from the animal contain virus and it is present in the blood system. The virus can be spread between horses by biting insects, multiple use of surgical instruments, grooming implements, other equipment such as stomach tubes, and from a dam to her foal in the milk.

Risk period

The disease occurs more commonly during a good wet season when river systems flood and there are large numbers of biting insects.

Monitoring and action

A vet will need to collect blood samples to conduct serological testing. It may be 45 days from the point of infection before antibodies can be detected in the blood.

Control

No specific treatment or vaccine is available.

Eradication of the disease from a property can be achieved by testing, then removal or destruction of the positive reactors. Horses that are intended to be brought onto the property in the future should be tested before entry to ensure they are not carriers of EIA.