What is equine influenza?

Equine influenza is a virus which causes acute respiratory disease in horses. It is highly infectious.  It is thought that the disease has a nearly 100% infection rate in an unvaccinated horse population with no prior exposure to the virus, such as Australia before the 2007 outbreak.

The virus can be spread by coughing or if the virus is present on surfaces.  It can be readily inactivated by a variety of disinfectants and chemicals.

The outbreak of equine influenza and quarantine measures

On 8 August 2007, horses arrived from Japan at Tullamarine Airport, Melbourne. Four of these horses were then flown to Kingsford Smith Airport, Sydney, where the Australian Quarantine and Inspection Service (AQIS), an arm of the Commonwealth Government, ordered them into quarantine at the Eastern Creek Quarantine Station. At the time the four horses arrived in Sydney, at least one of those horses was infected with equine influenza. While in quarantine that horse or horses became infectious.

Sometime between 10 and 17 August 2007, equine influenza escaped from the Eastern Creek Quarantine Station. By 29 October 2007, there were more than 7,000 infected premises in NSW and Queensland.