Equine Influenza - EI

These guidelines discuss the principles of disease prevention and control for Equine Influenza (EI) and apply to stud farms of all types and sizes. Not to take appropriate steps to follow them, in consultation with attending veterinary surgeons and, where appropriate, expert advice, will undoubtedly increase the risk for introduction of EI onto the stud farm and increase the risk of spread of EI within and from the stud farm. This will potentially compromise animal health and welfare and the successful activities of stud farm businesses, racing and other equine events.

The Disease

Equine Influenza (EI) is a highly contagious, rarely fatal, respiratory disease of horses, ponies and other equine animals, caused by the equine influenza virus. Although historically there were two subtypes of the virus: H7N7 and H3N8, for more than 30 years now only the H3N8 subtype has been shown to be circulating and does so now as two distinct clades, known as Florida clades 1 and 2. EI viruses are distinct from the viruses that cause human and avian influenza. EI occurs all over the world with the known exceptions of Australia (where a major incursion occurred in 2007, followed by eradication), New Zealand and Iceland. A major outbreak of EI Florida Clade 1 occurred in north western Europe, including UK, Ireland, France and Germany, in late 2018 and into 2019, mostly involving unvaccinated horses but also some vaccinated horses.