Respiratory disease in imported horses in quarantine le 16/07/2009

The Australian Chief Veterinary Officer, Dr Andy Carroll, has advised today that a number of imported horses of various types and backgrounds at Eastern Creek Quarantine Station have been showing signs of Equine Herpes Virus 4 (EHV-4). This is the respiratory form of the herpes virus in horses.

EHV-4 is endemic in Australia (it has been here for many years), it is not a notifiable disease and is not a quarantine concern – but is has been circulating within Eastern Creek.

Horses can be « silently » infected with herpes virus, not shed the virus and show no clinical signs in Pre Export Quarantine.

If horses are stressed, for example by international travel, the infection by EHV-4 can come back again and the horse may start shedding the virus.

All outbreaks of any infectious disease in quarantined horses must be investigated. Because these horses have respiratory signs, all the horses have been repeatedly and thoroughly tested. No horse has tested positive to Equine Influenza (EI) virus, but one horse has given a mild serological reaction to EI. This is not unusual because all the horses have been vaccinated against EI. All horses will all be tested repeatedly to make absolutely sure there is no EI circulating before they released from quarantine.

These horses are more than two weeks into their 3-week Post Arrival Quarantine (PAQ). This PAQ period will be prolonged to ensure all additional testing and other measures show the horses do not have EI, and all the experts are satisfied there is no risk.

These horses currently present no danger to Australia’s domesticated horses. This incident indicates that the strengthened quarantine procedures introduced after the 2007 EI outbreak are working in that:

. horses in PAQ are being closely monitored and tested

. cases of fever and respiratory disease are being thoroughly investigated

. communication between Commonwealth and State animal health authorities and horse industry organisations has improved

. it reinforces the need for a PAQ of 3 weeks when consignments from different origins are commingled for the first time in PAQ.

A quote from Dr. Andy Carroll, « There is currently absolutely no evidence of EI virus at Eastern Creek. »

Source : the Horse Industry Council