The Hendra Virus

One horse has died and another horse was put down.

25 staff from the Brisbane Veterinary Clinic have been tested for the virus and are awaiting the results.

Hendra virus is not highly contagious, but if transmitted to horses and humans, can be lethal.  Please contact your vet or the respective Dept. of Primary Industries if you observe suspicious symptoms, for example unusual behaviour, head tilt, and recumbence (leaning or lying down).  For other possible symptoms, see also below.

Hendra Virus was first discovered in Hendra, Queensland, in September 1994 when horse trainer, Mr Vic Rail, his stablehand and most of his horses became ill. Mr. Rail and 14 horses died.

Further cases have occurred in Queensland in 1995, 1999 and 2004 and one case was reported in Northern NSW in 2007.

It was discovered to be a completely new virus, which seems to be hosted by Fruit Bats, meaning that they carry the virus but are not affected by it.

Hendra virus does not cause clinical disease in fruit bats, but if transmitted to horses it can cause serious illness, including respiratory distress, frothy nasal discharge, fever, elevated heart rate and death. The four humans known to have been infected with Hendra virus were apparently infected after exposure to large amounts of virus that had been amplified in infected horses. There have been no other documented cases of human infection in Australia.

According to the Qld DPI website:

The Clinical Symptoms in previous outbreaks have been:

·         respiratory distress

·         frothy nasal discharge

·         elevated body temperature (above 40°C)

·         elevated heart rate (increased to around 90 or 100 beats/minute).

In addition to those listed above, other signs that increase the likelihood of the virus being present are:

·         facial oedema

·         terminal bloody nasal discharge

·         neurological signs - two horses that recovered had mild neurological signs, including muscle twitching. (Neurological signs may be due to either encephalitis or vascular infarcts in the brain.)

Although the virus is not very contagious, it is important that any cases are rapidly diagnosed and that adequate precautions are taken to avoid contact between infected animals and susceptible animals and humans.

Hendra virus (HeV) causes a broad range of clinical signs in horses. Hence many conditions could be regarded as 'possible' and require HeV exclusion. However, it is clear that HeV in the horse is a rare occurrence.

It is known that close contact with HeV-infected body fluids, particularly blood and thoracic fluid from an infected horse can cause infection in humans.

Prevention

These preventive measures in horses are based on extrapolations from the limited epidemiological information available.

Stabling horses or moving them away from focal points of bat activity during the high-risk months of August to January should decrease the risk of exposure as all cases to date have occurred in horses kept in open paddocks where bat activity has been observed. (A horse brought in from an open paddock where bats were active initiated the first observed outbreak in the stables.)

Placing horses in paddocks that do not contain trees attractive to bats for either feeding or roosting should also decrease the risk of exposure. As well, horse-feed bins or watering points should not be placed under trees when there is a risk of bats coming in to that tree for feeding, resting or roosting.

As a precaution, remove dead flying fox pups and dead flying foxes from the horse area if found. This should be done in a way that does not expose the handler to any fluids associated with the dead flying foxes. Disposal can be undertaken by burial or burning.

It is important to monitor the health of your horses carefully and report any suspicions to a veterinary practitioner or to the Department of Primary Industries in your State.