Australian scientists with the Commonwealth Scientific and Industrial Research Organisation (CSIRO) claim to have made a breakthrough discovery on how the horse virus Hendra spreads.
Funded by the Australian Biosecurity CRC for Emerging Infectious Diseases, Dr Deb Middleton and her team at Australian Animal Health Laboratory (AAHL) have defined the period following the first signs of disease when horses are most likely to shed Hendra virus and therefore infect other horses and people.
Thus there is now an opportunity to diagnose Hendra virus in horses early, prior to advanced clinical signs and the highest risk of transmission.
"Unlike in horse flu, where apparently healthy horses can transmit the virus, horses in the early stages of Hendra infection generally appear to be at lower risk compared to animals with more advanced signs of illness," says Middleton.
Although it is still not known how Hendra spreads from flying foxes to horses, Dr Middleton says the key to preventing human exposure and the exposure of additional horses is first understanding the disease in horses and secondly controlling the viral spread from diseased horses.
"Developing a sensitive and specific stall-side test, which vets could use out in the field to diagnose the disease, has become even more important. However there are still key challenges to developing this type of advanced technology."
First identified in Brisbane in 1994, Hendra virus, which spreads from flying foxes, has regularly infected horses in Australia. Of the 11 equine outbreaks, four have led to human infection, with three of the six known human cases being fatal, the most recent of these in August 2008.
Dr Middleton says limited information in the past, on when the disease can transmit, has made it difficult to manage infected horses to stop Hendra spreading further to people and other susceptible horses.
"Our research has determined the best biological samples required for rapid diagnosis of the virus in horses and identified the important relationship between the period of highest transmission risk and the time with which the disease can easily be detected," she adds.
As a result of these findings, veterinarians and horse owners are likely to consider the possibility of Hendra virus infection sooner when dealing with sick horses. This will mean appropriate management strategies can be put in place immediately, reducing the risk of spread while testing is being carried out.
These research findings will be used to update the guidelines that horse owners and vets use to handle potential Hendra virus infections.
Australian Veterinary Association president Mark Lawrie said, "We need scientists and technology to prevent us from future outbreaks," he said.
"Almost 75 per cent of new diseases that have emerged in humans in recent years are animal-based.
"The closer interaction of domestic animals and wildlife has led to this (and) Hendra is a classic example."
He said research would keep vets ahead of the game but he urged horse owners to abide by preventative measures such as keeping horses away from flying fox habitat.