Equine infectious anaemia: how to spot and report the disease

Equine infectious anaemia (EIA), also known as swamp fever, affects horses, donkeys, mules, zebras and other equidae. It is a retrovirus commonly transmitted by blood-sucking insects. It does not affect humans.

Clinical signs

Some infected animals do not show signs of disease, or signs are overlooked because they don’t last for long.

Clinical signs can include:

• recurring fever
• tiredness, weakness and depression
• loss of appetite and weight loss
• frequent urination
• diarrhoea
• paralysis of the hindquarters
• pinpoint bleeding beneath the tongue
• pale mucosal membranes
• discoloration (yellowing) of the eyes
• rapid breathing and accelerated pulse
• abortion in pregnant mares

Potential lifetime carriers occur because the virus persists in white blood cells.

EIA can present as a recurring fever, but most progress to silent carrier states. 

How equine infectious anaemia is spread

EIA is most commonly transmitted by large horseflies which are usually active from May to September, peaking in July and August. EIA can also be transmitted through blood and saliva spread through medical equipment, instruments and needles, as well as milk, and body secretions, such as semen of infected animals.

The horseflies may only travel short distances to feed, but the virus can be carried over long distances by infected horses or contaminated equipment and products.

Vaccination

There is no vaccination available for EIA. The key to prevention is the identification and restriction of infected horses.

Human health implications

There are no human health implications because the disease is not zoonotic.

How to control the disease

The Equine Infectious Anaemia Control Strategy for Great Britain  sets out the disease control measures we would take if EIA was suspected or confirmed in Great Britain.

If the disease is confirmed the outbreak will be controlled in line with the contingency plan for exotic notifiable diseases.

Legislation

The main domestic legislation on EIA is the Infectious Diseases of Horses Order 1987.

Within Scotland: The Specified Diseases (Notification and Slaughter)(Amendment) and Compensation (Scotland) Order 2014

Biosecurity

The Government's policy on disease control is that prevention is better than cure. This approach works by reducing the chances of a disease entering the animal population, and if it does then it can be quickly spotted and dealt with through the preventative measures.

Biosecurity is about being aware of the ways disease can spread, and taking every practical measure to minimise the risk of disease spreading.