An overview of equine exotic diseases

Ninety seven per cent of equine professionals fear that potentially fatal exotic diseases, such as West Nile Virus, will hit the UK devastating the country’s equestrian industry, both on a welfare and financial front, according to a recent survey¹ from Intervet UK. 

With climate change increasing the risk of insect-borne exotic diseases in this country, it is essential that horse owners are aware of the clinical signs of these potentially fatal diseases to help prevent them from spreading.  However, shockingly, it’s thought that 96 per cent of those surveyed would not be able to identify these signs.

There are three main exotic diseases that could wreak havoc on the UK’s equine industry if there were an outbreak.  These are West Nile Virus, African Horse Sickness and Equine Infectious Anaemia (Swamp Fever).

West NileVirus

West Nile Virus is a potentially fatal, zoonotic disease (a disease that can be transmitted between humans and animals) which can also affect dogs, cats, bats, squirrels and domestic rabbits.  Spread by mosquitoes that have fed on infected birds, the clinical signs in horses include loss of appetite, depression, fever, paralysis of hind limbs and incoordination.  Mortality rates among clinically affected horses have varied from 10 to 60 per cent in different outbreaks.

The disease is endemic in the US and PreveNile™, a unique vaccine available in the US based on a human yellow fever vaccine, has already proven to be a highly effective means of disease prevention.  Closer to home, there have been outbreaks in Romania, Spain, France and Italy but no vaccine is currently available in Europe.

African Horse Sickness

African Horse Sickness is another potentially fatal viral disease which is similar to Bluetongue in that it is spread from horse to horse via midges.  It has a high (90 percent) mortality rate and the clinical signs include fever, breathing difficulties, frothy discharge and sudden onset of death.  There have been outbreaks of African Horse Sickness as near as Spain in 1987 and Portugal in 1989 and its close relationship to Bluetongue highlights the risk of outbreaks occurring in the UK.  Vaccines are currently available to help prevent African Horse Sickness, but they are not licensed for use in Europe.

Equine Infectious Anaemia (Swamp Fever)

Equine Infectious Anaemia (Swamp Fever) is spread from horse to horse by infected horse flies.  Its clinical signs include fever, loss of appetite, weight loss and anaemia.  However, most horses infected with Equine Infectious Anaemia develop antibodies to the virus (several weeks after infection), show no clinical signs at all and remain carriers of the virus for the rest of their lives.

There have been outbreaks of the disease in Russia, the Balkans, Romania and Turkey.  Indeed, closer to home, Italy regularly reports sporadic outbreaks and there have been recent cases in Germany and France.  There was an outbreak in the UK in 1976 and more recently, in 2006, an outbreak occurred in Ireland thought to be caused via the introduction of plasma from Eastern Europe.  This highlights an increased likelihood that Equine Infectious Anaemia could again reach the UK.  There is no current vaccine for the control of Equine Infectious Anaemia.

Diseases that are historically thought of as exotic are steadily moving towards our shores. It is important to remain vigilant and track the movement of these diseases so that they can be understood and, if we do have an outbreak, controlled.

For further information on PreveNile, which is currently available in the USA, please log on to www.prevenile.com.