What is African Horse Sickness?
African Horse Sickness is a highly fatal and infectious disease, which affects horses, mules, donkeys and zebras. It is carried by and spread by biting insects. The spread of the disease is similar to Bluetongue, in that it is not directly contagious between horses as it is influenced by climatic conditions which favour the spread of carrier insects. It is presently endemic in Sub-Saharan Africa. Dogs can also be severely infected by the virus, usually by eating infected horsemeat.
Clinical signs
The clinical signs seen are different depending on what form of the disease is present.
- affected horses have a high fever, severely laboured breathing, coughing and profuse discharge from the nostrils. The mortality rate is very high with up to 95 per cent of horses dying within a week
- in the cardiac form of the disease, which has an incubation period of from seven to fourteen days, swellings are present over the head and eyelids, lips, cheeks and under the jaw. The mortality rate is around 60 per cent and death results from heart failure
- the mixed form of the disease is a combination of the above two types. It has an incubation period of from five to seven days and the disease shows itself initially by mild respiratory signs followed by the typical swellings of the cardiac form
- horse sickness fever is the mildest form, characterised by a fever with low temperatures in the morning rising to a high peak in the afternoon
How is the disease transmitted?
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.
Is there a vaccine available?
No vaccine for AHS is currently licensed in the EU. Use of a modified live vaccine for AHS (such as the one being produced by OBP) carries a risk of vaccine virus reversion to wild type (i.e. the virus used in the vaccine can potentially undergo changes that mean it could actually infect vectors, and subsequently susceptible equidae). Thus at the present time, the vaccine will not be considered for use in the UK other than in an emergency situation.
What legislation currently exists?
Provisions for the control of African Horse Sickness are contained within the African Horse Sickness Regulations (NI) 2013.
Imported horses from at-risk countries outside the European Union are routinely tested for African Horse Sickness. The severity of disease could significantly affect the Equine Industry in the United Kingdom, particularly in southern UK, where this disease is most likely to occur.
DAERA advises that you do not import horses from any territory or take horses to compete in any territory in which African horse sickness is present or which vaccinates against African horse sickness.
If you suspect the presence of the disease, contact your local Divisional Veterinary Office immediately, or call the DAERA helpline on: 0300 200 7840.