African Horse Sickness (AHS) is a highly fatal and infectious disease, which affects horses, mules and donkeys. It is carried and spread by biting insects.

The disease is notifiable: if you suspect the disease, you must immediately notify the duty vet in your local Animal Health Veterinary Laboratories Agency (AHVLA) office.

The disease is not directly contagious between horses, has never occurred in the UK but is present (endemic) in sub-Saharan Africa. Dogs can also be severely infected by the virus, usually by eating infected horsemeat.

Latest situation

• The disease has spread as far north as Morocco and the Middle East. Zebras and elephants may be infected without showing signs of disease. Details of the latest situation can be found on the international disease monitoring web pages
• May 2011 – Defra are preparing new regulations for this disease.

About the disease

AHS is caused by an orbivirus, and there are nine strains of the virus. Affected horses have a fever with laboured breathing, coughing and discharge from the nostrils. A less serious form can occur causing fever and swelling of the face.

Spread/transmission of disease

The spread of disease is influenced by climatic conditions which favour the spread of carrier insects (vectors) including warm, moist weather and high rainfall, as well as spread by wind dispersal. It is likely that the virus persists (overwinters) in other, unknown species in Africa when the insect is not active. This explains why the disease does not persist in other countries following an outbreak.

Disease prevention

Housing horses in accommodation at times of peak midge activity will reduce the likelihood of midge attack but it is unlikely to fully protect your horse. A combination of protection measures is recommended to ensure the highest possible degree of protection is achieved. See:

• Further details on protection measures (PDF 36KB)
• African horse sickness – How to spot the disease (March 2009) (PDF 1.2 MB)

GB Legislation

From 1 January 1993 AHS is included in The Specified Diseases (Notification and Slaughter) Order 1992 to implement the slaughter requirements of EU Council Directive 92/35/EEC which lays down control rules and measures to combat African horse sickness (Official Journal of the European Community: No. L157, 10.6.92 p.19). Imported horses from at-risk countries outside the European Union are routinely tested for African horse sickness.

The severity of disease and the controls to monitor and restrict movement of horses could significantly affect the Equine Industry in the United Kingdom, particularly in southern UK, where this disease is most likely to occur.

Legislation

From 29 April 1992 European Council Directive 92/35 provides for compulsory notification, and the setting up of a protection zone of least 100 kilometres radius around and infected premises. This, together with a surveillance zone of at least a further 50 kilometres, would have to remain in force for at least 12 months.

Further information

• Consultation on proposals to implement council directive 92/35/EEC on the control of AHS (on the National Archives website)