July 16, 2008

The dangerous Hendra virus has shown its ability to jump between species, with a staff member at a Brisbane clinic at the centre of an outbreak returning a positive test.

The staff member spent a night in hospital for assessment but was discharged the next day. They are not showing signs of the disease, which is carried by fruit bats.

All 25 staff at the clinic have given blood to be tested for the virus and this is the only positive result returned.

It is understood that antibodies to the virus may take up to a fortnight to appear in test results so further testing is expected.

Two horses at the clinic have died from the disease - one from the virus and the other was euthanised because of the seriousness of its condition. The 37 remaining horses have so far tested clear for the disease.

In other news, an unrelated fatal third case has been identified in far north Queensland.

The worst outbreak was in 1994 when trainer Vic Rail and 14 horses died. The virus was first identified as a result of those cases.

There have been only four confirmed human infections, all in Queensland, and two of these died. All four cases had been in close contact with very sick or dead horses.

Symptoms in humans include:

Horses develop an acute respiratory syndrome quickly leading to death in most cases.

Hendra does not appear to be very contagious, but humans and horses are susceptible to the disease. All human infections have occurred following direct exposure to tissues and secretions from infected horses at the late stage of their illness or after death. There is no evidence of human-to-human transmission.

The incubation period in humans has been estimated at 5-14 days.

It is not clear how horses become infected, but this may occur by them eating food contaminated by bat urine or birthing byproducts.

No specific antiviral treatments are known to be effective against Hendra, nor is there a vaccine.