African horse sickness


If you keep horses, donkeys or mules you will want to be aware of this fatal disease

This guidance is for England

African horse sickness is a disease that affects equidae - that is, horses, donkeys and mules. It is an infectious and fatal disease and is classified as an orbivirus.

It does not spread directly from one horse to another, but is transmitted by the Culicoides midge, which becomes infected when feeding on other infected equidae.

It has never been present in the UK. It occurs mostly in the warm and favours the heavy rainfall in sub-Saharan Africa where it is endemic.

What is the possible impact of the disease?

African horse sickness is a notifiable disease; therefore you must contact the Animal and Plant Health Agency (APHA - 03000 200301) if you suspect the disease.

Due to the nature of the disease, any animals suspected of having it would be isolated and movement restrictions would be put in place. Blood tests would be undertaken to confirm the disease and any infected animals may be slaughtered.

Clinical signs

There are four forms of the disease: (i) one affects the lungs, (ii) another the heart, (iii) is a mixture of these two and (iv) is a mild form of the disease.

The lung form can show the following signs:

  • very high fever
  • difficulty in breathing with mouth open and head hanging down
  • frothy discharge may pour from the nose
  • sudden onset of death

The heart form can show the following signs:

  • fever, followed by swelling of the head and eyes (in severe cases the entire head swells)
  • loss of ability to swallow and colic signs may occur
  • bleeding (of pinpoint size) in the membranes of the mouth and eyes
  • slower onset of death than the lung form, occurring four to eight days after the fever has started
  • lower death rate than the lung form

The mixed form is characterised by signs of both the above forms of the disease.

The mildest 'fever' form is characterised by fever without other clinical signs and has the lowest death rate.

What happens if disease is confirmed?

The premises where disease is confirmed will be put under restriction so no animals can move on or off.

A control zone, protection zone and surveillance zone may be set up around the infected premises.

The control zone must have a radius of at least 20 km, the protection zone must have a radius of at least 100 km and the surveillance zone must have a radius of at least 150 km, each centred on the part of the premises that Defra considers most appropriate for disease control.

Horses contained within these zones may be placed under movement restrictions and be required to be tested.

Can people catch the disease?

African horse sickness does not affect humans so there are no human or public health implications.

What can be done to reduce the risks?

Maintain good biosecurity. Guidance on biosecurity is available on the GOV.UK website.

If you import any animals, ensure that they are isolated and monitored. All imports must comply with the legal requirements and you must ensure that all documentation for imported horses is complete and accurate.

If you are concerned that your horse, donkey, etc is unwell, you should contact your local veterinary surgeon.

If you suspect that your horse has any of the clinical signs of African horse sickness then this needs to be reported immediately to APHA, as well as your private veterinary surgeon. Information on notifiable diseases in animals can be found on the GOV.UK website.

Legislation applicable to African horse sickness

The African Horse Sickness (England) Regulations 2012 make provisions for dealing with any suspected and confirmed cases of African horse sickness. They give powers to set up control zones and allow veterinary officers to take blood samples from animals within the zones.

The Regulations set out special provisions for dealing with slaughterhouses and non-captive horses, and prohibit vaccination against African horse sickness except in the circumstances covered within the Regulations.

Further information

The African Horse Sickness Control Strategy for Great Britain is available on the GOV.UK website.

Trading standards

For more information on the work of trading standards services - and the possible consequences of not abiding by the law - please see 'Trading standards: powers, enforcement and penalties'.

Key legislation

Last reviewed / updated: June 2020

In this update

No major changes

Please note

This information is intended for guidance; only the courts can give an authoritative interpretation of the law.

The guide's 'Key legislation' links may only show the original version of the legislation, although some amending legislation is linked to separately where it is directly related to the content of a guide. Information on amendments to legislation can be found on each link's 'More Resources' tab.

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