Further Hendra Virus Tests Negative at Affected Farm

The Hendra virus tests on 25 horses at a Cawarral, Queensland, property, as well as nine others that left the property, continue to return negative results. Three horses on the property died in late July and early August. Two of the dead horses were confirmed positive for Hendra, a potentially zoonotic virus that has only occurred in Australia.

Biosecurity Queensland acting Chief Veterinary Officer Rick Symons, BVSc, MBA, PhD, said the clear results included the horse that had returned a positive result to one of the tests last Friday.  

"We re-tested this horse and these results are negative, however we need to wait for the results from the next round of testing in the coming weeks before we can be absolutely certain," Symons said. "This applies to all of the horses involved."

Eleven horses that left the affected property before the quarantine have all been traced and tested, Symons noted. The results for nine of these horses are negative, one is undergoing further testing, and authorities are awaiting advice on the results from the final horse that was traced to New South Wales.

Fruit bats (known as flying foxes in Australia) indigenous to Australia appear to be Hendra's natural host. Typical equine clinical signs of Hendra include respiratory distress, frothy nasal discharge, elevated heart rate, and increased body temperature. Some horses display neurologic signs, such as head-pressing or twitching, while others might appear to be colicky. In past cases, human infections have occurred from handling infected horses (ill horses and during autopsies), so great care should be taken in regard to personal protective measures.

The tests conducted so far include PCR testing, which shows any presence of the virus in a horse´s blood or mucus, serological tests that indicate if a horse has had a reaction to the virus and is producing antibodies, and an ELISA test, which also scans for antibodies.

Symons said all results to date were the first stage in a series of tests to eliminate the possibility of further Hendra virus infections.

"I stress that further testing of the horses over the next few weeks will be required," he said. "This is necessary as the antibodies that demonstrate previous exposure to Hendra virus take time to develop and be measured by diagnostic tests.

The Cawarral property and a neighbouring property will remain under quarantine until Biosecurity Queensland is confident there is no chance of any further infection.

Biosecurity Queensland will continue to monitor all of the properties and horses concerned and has hired an independent reviewer to audit procedures in use.

If anyone suspects a case of Hendra virus, contact Biosecurity Queensland immediately on 13 25 23 or contact the Emergency Disease Watch Hotline on 1800 675 888.

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