What all owners need to know about African Horse Sickness
PUBLISHED: 16:49 03 September 2018 | UPDATED: 16:50 03 September 2018
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We’ve enjoyed stunning weather this summer but if it’s a sign of things to come as the climate warms there could be unexpected, and deadly - consequences. Sheena Grant reports on why horse owners are being advised to learn about African Horse Sickness.
A deadly horse disease dubbed the ‘Armageddon’ of animal illnesses could reach our shores as the climate warms, experts are warning.
African Horse Sickness (AHS) has a 90% mortality rate and, should it arrive in this country, could devastate horse populations, which have no natural immunity.
Sixty-mile protection zones could be put around stricken stables, devastating Britain’s £7 billion equine industry - much of which is centred around Newmarket, the country’s horse racing capital - putting an end to race meets and other equestrian events.
There has been no outbreak of AHS in Europe since Spain was affected in 1990 but if this year’s heatwave is a sign of things to come as the climate warns, vets fear that, along with a lack of biosecurity measures by importers, could allow the disease to strike.
The British Horse Society says the type of midge which spreads AHS is already in Britain and recent UK outbreaks of bluetongue in sheep, which is related to the AHS virus, prove it could exist in our climate. The bluetongue outbreak is thought to have occurred after infected midges were blown into the country by winds from mainland Europe. Studies have shown that if caught in specific weather conditions, especially over water, the midge can be carried for more than 200km.
AHS “is classed as one of the most devastating equine diseases” says the British Horse Society, affecting horses, donkeys, mules and zebras. “Horses are the most susceptible species and up to 90% of infected horses die. Mules have a mortality rate of 50-70% and donkeys 10%. Zebra act as a reservoir host for the virus and they do not usually display any signs of the disease.
“AHS could have serious potential ramifications for the £7 billion equine industry. Previously AHS was not seen as a great threat to British horses, largely because of the difference in climate between Britain and Africa. However, it is very similar to the bluetongue virus and the outbreak of bluetongue that occurred in 2007 has shown that it may be possible for AHS to occurr in Britain. Additional factors, such as the increase in global travel and climate change, also contribute to concern about the disease.”
Horses cannot catch AHS from one another - the disease is transmitted by the bite of an infected female midge. Although there are 50 known species of Culicoides midge - including one that can cause the unrelated allergic reaction, sweet itch, in susceptible horses - already present in the UK there has been no AHS so far, although it is assumed that Culicoides midges in Britain may be capable of carrying the AHS virus.
Roly Owers, chief executive of Norfolk-based World Horse Welfare, said: “Exotic disease does present a real risk for the UK’s horse population, and African Horse Sickness is certainly the ‘Armageddon’ of diseases due to its extremely high fatality rate plus the fact there is currently no effective vaccine. There is a real need for UK horse owners to improve biosecurity which is a vital tool in helping to control all diseases.”
Defra currently views the current risk of AHS reaching the UK as very low and horses exported from Africa are subject to stringent testing and quarantine but Mr Owers warned that not all owners and breeders were taking the necessary precautions to prevent disease entering Britain.
“Early results from a survey undertaken by the Equine Disease Coalition show that many horse owners are not undertaking even the most basic biosecurity measures, such as isolation procedures for new arrivals, and this is a real cause for concern,” he said.
AHS is endemic in eastern and central Africa. Over the last 50 years, outbreaks outside of Africa have occurred in the Middle East, India, Pakistan, Spain (mid-1960s and 1987-90) and Portugal (1989).
More about AHS
Experts say the most likely way for AHS to enter the UK is by infected Culicoides midges being blown in on prevailing winds, should an outbreak occur elsewhere in Europe, or an infected midge being inadvertently flown in on a plane.
There are three main forms of AHS; lung form (acute, incubation period three to five days), heart form (cardiac, incubation seven to 14 days) and mixed form (combination of lung and heart form, incubation five to seven days).
Symptoms of the acute form include a high, rapid rise in temperature, breathing difficulties, excess sweating, frothy discharge from the nostrils, coughing. Symptoms of the cardiac form include swelling of eyelids, facial tissues, neck and shoulders, loss of ability to swallow, respiratory distress, colic symptoms.
There is no effective treatment for AHS. The BHS says all horse owners should make themselves aware of AHS and its clinical signs, so that in the event of an outbreak, the disease can be identified quickly and be promptly controlled.