In Hendra (a suburb of Brisbane) in 1994, a 49-year-old horse trainer died after a fulminating pneumonic illness, and a 40-year old stable worker survived an influenza-like illness. These two cases occurred following a sudden outbreak of an acute respiratory syndrome among thoroughbred horses in a training complex. Both human cases had extensive close contact with respiratory secretions and other body fluids of several very ill horses . The incubation periods of the two cases were estimated to be five and six days. Surveillance of about 90 other people exposed to infected horses identified no other human cases.
In 1995 in Mackay, north Queensland, a 36-year-old horse trainer died from severe encephalitis caused by Hendra virus. Subsequent investigations indicated he had been exposed to Hendra virus 13 months earlier whilst assisting a veterinarian undertake a post-mortem examination on two horses. He also had direct ante-mortem exposure to their respiratory secretions (personal communication, Simon Bewg, Biosecurity Queensland, September 2006). Of note, he was hospitalised with aseptic meningitis shortly after exposure to the horses, with recovery at the time and a long symptom-free period before his fatal illness. This initial illness was considered to have been a seroconversion illness, with an anamnestic response to viral antigens in the second and fatal illness (reinfection with Hendra virus or alternative cause of fatal illness both considered unlikely explanations). The veterinarian who conducted the post-mortem examination remained well.
In Cairns, north Queensland in late 2004, a veterinary practitioner aged in her 20s, performed a post-mortem examination on a horse subsequently presumed, based on clinical and epidemiological evidence, to have died of Hendra virus infection. The veterinarian had also attended to the horse in the last few minutes of its life and was extensively exposed to respiratory secretions and blood. About seven days later, she developed a mild influenza-like illness and showed evidence of seroconversion to Hendra virus. At follow-up four years later, she remained well. Three other people who were also exposed remained well and did not seroconvert.
In July 2008, a veterinary hospital at Redlands (a suburb of Brisbane), was quarantined after four horses with neurological signs tested positive to Hendra virus. Another horse developed clinical signs while under quarantine. Two of the staff members caring for the horses in the clinic prior to confirmation of Hendra virus infection, developed an acute influenza-like illness followed by encephalitis and seroconversion to Hendra virus. One of them subsequently died. One case was exposed to the virus during post-mortem examination of a horse subsequently confirmed as infected with Hendra virus (possible 16-day incubation period) and both cases were exposed while performing nasal cavity lavage in the three days before the onset of clinical signs of disease in another horse (possible incubation periods of nine and 11 days).
In August 2009, at an equine nursery at Cawarral near Rockhampton, central Queensland, a 55-year-old veterinarian performed a nasal endoscopy on a horse that was subsequently presumptively diagnosed (based on both clinical signs and exposure to a laboratory-confirmed equine case) with Hendra virus infection. The procedure was performed without respiratory protection or gloves while the horse had a fever and respiratory distress. Endoscopic examination showed visible petechiae and ecchymoses in the respiratory tract. The veterinarian was given a five-day course of ribavirin from day 14 post exposure, but developed an influenza-like illness 21 days post exposure followed by encephalitis and death. Three other people with extensive exposure to the blood and respiratory secretions of the horse (and a second horse involved in the same outbreak and confirmed as having Hendra virus infection) remained well and did not seroconvert. These three people were also given ribavirin prophylaxis.
Details of Hendra virus incidents can be found at Biosecurity Queensland
The NSW Department of Primary Industries and the QLD Department of Agriculture and Fisheries also provide information on Hendra virus.