Dr Sue Hides, who is acting director of Victoria's State Disease Control Headquarters, said although there are currently 7587 infected properties declared in the New South Wales and Queensland, the figure is misleading.
"Practically, only the infected properties reported in the last 21 days will still be harbouring active infection.
"The number of active infected properties is therefore not 7587, but nearer 1410. At an average of 10 horses per property, this means that about 14,100 horses (out of a population of about 1 million) are currently infected.
"This means that about 1.4% of the total horse population are currently affected by EI."
Victoria, which is free of the disease, has closed its borders to horses since the outbreak began.
Since then, 269 investigations have been conducted and more than 565 horses tested for equine flu, with no positive test results recorded.
"This does not mean that Victorian horse owners can afford to relax their guard," says Dr Hides. "Vigilance will continue to be the 'watchword' for the next few months.
"Commonsense biosecurity measures will still apply, and all role-players should continue to ensure that the risks to the industry are minimised."
Dr Hides says there has been a lot of misinformation about EI being present in Victoria.
"Please note that this is not true. Should EI be found in Victoria, a stock standstill would be immediately implemented."
Victorian authorities have carried out 303 border movement investigations, including 21 alleged illegal movements which are still subject to inquiry. To date, 21 warning letters have been sent and two cases are under investigation for possible prosecution.
Investigations into the majority of alleged illegal movements have revealed that no breaches of the movement restrictions occurred.