Summary of Hendra virus incidents in horses

Hendra virus (HeV) was first isolated in 1994 in horses at a racing stable in Hendra, Brisbane.

The table below shows the location and date of each confirmed and possible HeV equine cases in Queensland and New South Wales, including clinical signs, observations in horses and other evidence.

DateLocation Confirmed cases Untested/
unresolved horses
Clinical signs and observations* Other evidence
August 1994 Mackay 2 0 Clinical signs to be confirmed* These cases didn't become apparent until late 1995 when HeV infection was confirmed in a person from Mackay. Testing of stored samples from horses was undertaken in late 1995.
September 1994 Hendra, Brisbane 7 13 Clinical signs to be confirmed* HeV was first identified and characterised as a result of this event. No diagnostic tests were available until after the event and not all horses were tested as samples were not retained from all horses. Strong epidemiological evidence exists for all horses involved to be considered as cases.
January 1999 Cairns 1 0 Clinical signs to be confirmed*  
October 2004 Cairns 0 1 Restlessness, elevated heart rate, increased respiratory effort and profuse sweating, fever, blood-stained frothy secretions issuing from its nose Strong epidemiological evidence exists for this horse. A veterinarian was confirmed serological positive for HeV after performing a necropsy on a horse that died suddenly with signs consistent with HeV. No samples from the horse were available for testing. The horse was the only identified potential source.
December 2004 Townsville 1 0 Depressed, fever, elevated heart rate and respiratory rate, brownish nasal discharge  
June 2006 Peachester 1 0 Opisthotonus, restlessness, vocalising (terminal), elevated heart rate, elevated respiratory rate, fever, markedly swollen lips, purple gums, died suddenly  
October 2006 Murwillumbah (NSW) 1 0 Lethargic, ataxic, penile erection, disorientation, mandibular swelling, dyspnoea, fever, wide-based stance, high stepping gait, occasional tongue protrusion, coughing  
June 2007 Peachester 1 0 Wide-based stance, rocking, relaxed penis, colic signs, inappetent, lethargic, depressed demeanour, elevated heart rate, recumbent and unable to rise  
July 2007 Cairns 1 0 Nasal discharge, wet lung sounds, fever, elevated heart rate, elevated respiratory rate, terminal neurological signs  
June 2008 Redlands 5 3 Horses 1–3: Unknown
Horse 4: Inappetent, depressed, maniacal/erratic behaviour
Horse 5: Head tilt, ataxic, circling, inappetent, depressed, fever, recumbent periods
Horse 6: Central neurological signs, severely ataxic, inappetent, depressed, recumbent, thrashing violently
Horse 7: Depressed, deteriorated rapidly
Horse 8: Febrile, depressed
Three horses have unresolved HeV status from this incident - all died at the veterinary clinic in the month before the first confirmed case with clinical signs consistent with possible HeV cases. Necropsies were not completed on the horses and only limited sub-standard laboratory samples were available for further testing with negative result for HeV.
July 2008 Proserpine 3 1 Horse 1: Unknown
Horse 2: Some respiratory manifestation, head down, non-responsive, elevated heart rate, swollen muzzle, recumbent, red fluids from mouth, died
Horse 3: Short neurological illness, ataxic, recumbent, horse appeared very stressed, trouble standing and walking
Horse 4: High stepping, dull
One horse has an unresolved HeV status from this incident - a companion horse was found dead several days prior to the first confirmed case. Limited clinical history consistent with HeV infection was available. A necropsy was not performed. One of the 3 horses with a positive laboratory test was non-fatally infected and antibody-positive.
July 2009 Cawarral 3 1 Horse 1: Unknown
Horse 2: Heavy breathing, nasal froth, fever, elevated heart rate, elevated respiratory rate, blood slow to clot, difficulty walking, collapsed, died
Horse 3: Progressive neuromuscular spasms, incoordination, died
Horse 4: Possible mild neurological signs—weaving, head pressing, ataxic on day of euthanasia
Strong epidemiological evidence exists for a horse which died 12 days prior to the first confirmed case. A veterinarian was confirmed positive for HeV infection after performing respiratory endoscopy on the horse. A second horse was confirmed as HeV positive on stored blood samples.
September 2009 Bowen 2 0 Horse 1: Shallow respiration, diaphragm twitching, muscle twitching, short stepping, reluctant to move, elevated heart rate, teeth grinding, head down, congested oral mucous membranes
Horse 2: Foam from mouth and nose, laterally recumbent with extensor rigidity, no gut sounds, fever, elevated heart rate, oral mucous membranes dry and congested, weak, jaw chomping, teeth grinding, rapid deterioration
A companion horse euthanased a month prior to the original confirmed case was also confirmed positive through laboratory testing.
May 2010 Tewantin 1 0 Twitching of mouth muscles, blindness, ataxic, seizures, inappetent, lethargic  
June 2011 Beaudesert 1 0 Increased respiratory effort, hind limb incoordination, depressed, fever, congested oral mucous membranes with petechial haemorrhage, died  
June 2011 Boonah 3 0 Horse 1: Colic, recumbent, thrashing
Horse 2: Twitching of muscles and eyes
Horse 3: Slight nasal discharge, dull, depressed, fever, elevated heart rate
Test results confirmed the presence of antibodies to HeV in a dog on this property. It was reported that the dog did not show any clinical signs of illness. No HeV genetic material was detected in PCR tests of samples collected from the dog on 3 occasions over a 3 week period. This was the first reported case of HeV antibody detection in a dog outside of an experimental setting.
June 2011 Logan 1 0 Ataxic, mild colic signs, fever, elevated heart rate, bloody ocular discharge  
June 2011 Wollongbar (NSW) 2 0 Horse 1: Fever, congested mucous membranes, ataxic with wide-based stance, asymmetrical facial paralysis, blindness, euthanased
Horse 2: Depressed, fever, slightly ataxic, dyspnoea, copious amounts of nasal foam bilaterally after euthanasia
July 2011 Park Ridge 1 0 Incoordination, fever, very weak, progression to death overnight  
July 2011 Macksville (NSW) 1 0 Sudden onset depression, blindness, head pressing, died 36 hours after first signs  
July 2011 Kuranda 1 0 Ataxic, disoriented, neck muscle fasciculation, circling, inappetent, recumbent, depressed  
July 2011 Lismore (NSW) 1 0 Found dead. Observed normal by owners 24 hours previously  
July 2011 Hervey Bay 1 0 Attempting to stand but stumbling, dry faeces, fever, elevated heart rate, oral mucous membranes injected, capillary refill time less than 4 seconds  
July 2011 Boondall 1 0 Mild clear nasal discharge, acute onset ataxia, intermittent inappentance, lethargic fever  
July 2011 Chinchilla 1 0 Terminal nasal discharge, ataxic, recumbent, dull demeanour, respiratory signs  
July 2011 Mullumbimby (NSW) 1 0 Found dead. Observed normal by owners 18 hours previously  
August 2011 Ballina (NSW) 1 0 Slightly ataxic then recumbent 12 hours later, muscle twitching, unable to stand and euthanased 3 hours later  
August 2011 South Ballina (NSW) 2 0 Both horses (mare and foal) found dead. Absentee owner  
August 2011 Mullumbimby (NSW) 1 0 Found dead. Observed normal by owners 15 hours previously  
August 2011 Gold Coast Hinterland 1 0 Gait problem, lethargic, fever  
August 2011 North Ballina (NSW) 1 0 Depressed, ataxic, wide-based stance. Found dead approximately 12 hours after onset of first signs  
October 2011 Beachmere 2 1 Horse 1: Unknown
Horse 2: Ataxic, large distended bladder, decreased gut sounds, lethargic
Horse 3: No clinical signs observed
A horse became acutely ill and was euthanased approximately 1 week before the first confirmed case. There were no samples available from this horse to be tested.
January 2012 Townsville 1 0 Bilateral serous nasal discharge, blind, ataxic, sudden brief irritation, dull, fever, elevated heart rate, elevated respiratory rate, oral mucous membranes injected, capillary refill time greater than 4 seconds, clotting time 2 minutes, ileus, facial swelling  
May 2012 Rockhampton 1 0 Elevated respiratory rate, fever, bilateral frothy nasal discharge, muffled heart sounds, bilateral epistaxis at death  
May 2012 Ingham 1 0 Fever, ataxic, circling, hanging head, dull demeanour  
June 2012 Mackay 1 0 Horse found moribund  
July 2012 Rockhampton 3 0 Horse 1: Ataxic, apparent blindness, droopy bottom lip and salivation
Horse 2: Off food, reluctant to move, extended neck, muscle fasciculation, and increased respiratory effort
Horse 3: Off food, dull demeanour, reluctant to move, hanging head, droopy bottom lip, ataxic, mild increase in respiratory effort, and pawing at ground
July 2012 Cairns 1 0 Inappetent, tremors, staggering, neurological signs worse on handling, slight nasal discharge, elevated heart rate, elevated respiratory rate, fever, delayed capillary refill time, congested conjunctival and oral mucous membranes, grinding teeth, penis protruding, muscle fasciculation, and blood from nose at death  
September 2012 Port Douglas 1 0 Ataxic, high stepping (left side), death  
October 2012 Ingham 1 0 Anorexia, slight bilateral nasal discharge, laboured respiration (respiratory rate 20), heart rate 60, lowered head, unsteady on feet, progression to recumbency  
January 2013 Mackay 1 0 Slow moving, ataxic, absent blink reflex, found dead approximately 24 hours after clinical signs were first noticed  
February 2013 Atherton Tablelands 1 0 Slow moving, off food, ataxic. Found dead several days after the onset of clinical signs  
June 2013 Macksville (NSW) 1 0 Observed normal in the early morning and found dead in the late afternoon  
June 2013 Brisbane Valley 1 0 Depressed, unsteady on feet, reluctant to move, elevated heart rate and muddy mucous membranes, deteriorated and euthanased  
July 2013 Gold Coast Hinterland 1 0 Off feed, dull, lethargic, elevated respiratory rate and mild bilateral serous nasal discharge, deteriorated to collapse, intermittent convulsions and unresponsive state, euthanased  
July 2013 Macksville (NSW) 1 0 Ataxic, weak, stumbling and rolling  
July 2013 Kempsey (NSW) 1 0 Ataxic, elevated heart rate, mild fever; neurological signs include loss of balance, staggering and laterally recumbent  
July 2013 Kempsey (NSW) 1 0 Observed seriously ill and failed to respond to antibiotics  
March 2014 Bundaberg 1 0 Off food, elevated respiratory rate, injected gums, frothy nasal discharge after death  
June 2014 Beenleigh 1 0 Off food, small amount of green nasal discharge turned bloody at later stage, ataxic, mild fever and toxic mucous membranes  
June 2014 Murwillumbah (NSW) 1 0 Found in swamp unable to stand  
July 2014 Gladstone 1 0 Altered gait, off food, depressed, mild mucoid nasal discharge, died overnight  
June 2015 Murwillumbah (NSW) 1 0 Lethargy for 2-3 days before to death  
July 2015 Atherton Tableland 1 0 Observed acutely ill 3 days before death. Ataxia, discharge, no respiratory distress  
September 2015 Lismore (NSW) 1 0 Observed to be unwell, off food, before it collapsed  
September 2015Gympie10 Acute disease onset with rapid deterioration over 24 hours. Depressed (obtruded) demeanour, injected/ congested gingival mucous membranes (darkened red/ purple change with darker periapical line and prolonged capillary refill time), tachycardia (75 beats/min), tachypnoea (60 breaths/min), normal rectal temperature (38.0°C), muscle fasciculations, head pressing and collapse, euthanisedThis case was not diagnosed until 2021 where it was determined to have the Hendra virus variant (HeV-g2).
December 2016 Casino (NSW) 1 0 The horse had been through a period of illness. Initial clinical signs observed included: failure to graze, nasal discharge, some ataxia, mild disorientation, weight loss and oral discomfort. Further behavioural abnormalities were seen prior to death Initial samples collected at the start of illness tested negative for HeV PCR. Further samples collected a few weeks after horse became unwell again tested positive for HeV serology which showed the horse had mounted a strong immune response. Additional samples collected several days post death with 1 weak HeV PCR positive result.
May 2017 Gold Coast Hinterland 1 0 Depressed, inappetent, not walking, mild fever, elevated heart rate and respiratory ate, euthanased after rapid deterioration  
July 2017 Lismore (NSW) 1 0 Off feed, wobbly of feet, lethargic, euthanased after health condition deteriorated  
August 2017 Murwillumbah (NSW)         1 0 Lethargic and not eating properly, unsteady on its feet and unwilling to move, decreased gut sounds, elevated temperature and poor blood circulatory function  
August 2017 Lismore (NSW) 1 0 Observed unusually quiet and disorientated 1 day prior to showing clinical signs – fever, increased respiration, poor circulation, teeth grinding, euthanased after rapid health deterioration  
Tweed Heads (NSW) 1 0 Depressed and not eating. Worse by the next morning, fever and staggering, euthanased 
June 2019 Scone, Upper Hunter Valley
1 0 Sudden onset of neurological signs and unresponsive, euthanased 

June 2020

Murwillumbah (NSW) 1 0 Depressed and having difficulty breathing, euthanased after rapid health deterioration        
October 2021 West Wallsend near Newcastle (NSW) 1 0

Neurological signs. Unvaccinated against HeV, euthanased after rapid health deterioration

This case was diagnosed as Hendra virus variant (HeV-g2).
Total  87, all deceased 20, all deceased   

*The clinical signs listed are taken from laboratory testing submission forms or media releases. Not all information for all cases was readily accessible to Biosecurity Queensland.