CSIRO Livestock Industries' scientists working at the Australian Animal HealthLaboratory (AAHL) in Geelong, Victoria, have made a major breakthrough in betterunderstanding how Hendra spreads from infected horses to other horses and humans.

Funded by the Australian Biosecurity CRC for Emerging Infectious Diseases, Dr DeborahMiddleton and her team at AAHL have defined the period following the first signs of diseasewhen horses are most likely to shed Hendra virus and therefore infect other horses andpeople.

First identified in Brisbane in 1994, Hendra virus, which spreads from flying foxes, hasregularly infected horses in Australia. Of the 12 equine outbreaks, the most recent being inAugust 2009, five have led to human infection, with four of the seven known human casesbeing fatal.

Dr Deborah Middleton and her team at AAHL have defined the periodfollowing the first signs of disease when horses are most likely to shed Hendra virus andtherefore infect other horses and people.

Dr Middleton says limited information in the past, on when the disease can transmit, hasmade it difficult to manage infected horses to stop Hendra spreading further to people andother susceptible horses.

'Our research has also determined the best biological samples required for rapid diagnosisof the virus in horses and identified the important relationship between the period ofhighest transmission risk and the time with which the disease can easily be detected,' DrMiddleton says.

As a result of these findings, veterinarians and horse owners are likely to consider thepossibility of Hendra virus infection sooner when dealing with sick horses. This will meanappropriate management strategies can be put in place immediately, reducing the risk ofspread while testing is being carried out.

'Unlike in horse flu, where apparently healthy horses can transmit the virus, horses in theearly stages of Hendra infection generally appear to be at lower risk compared to animalswith more advanced signs of illness.'

These research findings have been made available to update the guidelines that horse ownersand vets use to handle potential Hendra virus infections.

Dr Middleton says her team's research also indicates there is an opportunity to diagnoseHendra virus in horses early, prior to advanced clinical signs and the highest risk oftransmission.

'Developing a sensitive and specific stall-side test, which vets could use out in the fieldto diagnose the disease, has become even more important. However there are still keychallenges to developing this type of advanced technology.'

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 horsesis first understanding the disease in horses and secondly controlling the viral spread fromdiseased horses.

All research for the project was undertaken within AAHL's high-biocontainment facility.

Watch the ABC Catalyst episode on Hendravirus.

Watch All The Pretty Horses on Australian Story

Source: CSIRO.au. This article was published as part of theSpring edition of the CSIRO E-newsletter. The newsletter is published quarterly.

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