Australian Biosecurity CRC chief executive Dr Stephen Prowse, said about 50pc of flying foxes have carried the deadly virus at some time without any ill effects.

“All indications are that, on rare occasions, Hendra virus spills over from bats to horses and then from horses to humans – there are no known cases of people contracting Hendra virus from flying-foxes," he said.

Scientists believed Hendra virus to be a symptom of stress as a result of changes to the flying fox's traditional environment.

Despite recent annual outbreaks, Hendra infection is rare in horses and people, does not appear to be highly infectious and does not spread easily.

The people who need to take the most precautions are wildlife carers, horse owners and vets.

Horse owners need to minimise the likelihood of contact between fruit bats and horses, and both horse owners and veterinarians need to improve their biosecurity and infection control practices.

Director of the Anton Breinl Centre for Public Health and Tropical Medicine at James Cook University, Prof Rick Speare, recommended improvements in infection control among veterinarians and animal handlers.

“It is important that equine vets take the lead in implementing infection control in their day to day activities” Prof Speare said, who now worked with the Australian Veterinary Association (AVA), Biosecurity Queensland, Equine Veterinarians Australia and Queensland Workplace Health and Safety to assist veterinarians develop infection control strategies.

The AVA is developing improved biosecurity guidelines, and departments of agriculture and primary industries are holding workshops on personal and farm biosecurity.

More research is required to get a better understanding of how the virus persists in bats and spreads to horses, and for the development of vaccines, treatments and rapid tests so that in the medium term a multifaceted approach to biosecurity will be possible.

The public should not be unduly concerned about fruit bats, but treat them as they would any other wild animal and enjoy having them in their urban environment.

* For more information about Hendra virus research visit www.abcrc.org.au