The Hendra virus is unique to Queensland or northern NSW Australia. It was discovered in 1994 at a racing stable in the suburb of Hendra, Brisbane after a horse trainer and 14 of his horses died. Since, more than 90 horses have become infected, most have died as a result of infection or were euthanized to mitigate contamination. While hundreds of humans have been exposed there have been only 7 confirmed cases of contraction and 4 of those resulted in death.
To date research suggests that horses contact Hendra virus infection from ingesting food or water contaminated with the bodily fluids of flying foxes (fruit bats). The bats themselves are hosts and do not display symptoms or sickness. The specifics of how the disease transfers is yet unknown.
The prevalence of Hendra virus is low but once contracted it is one of the most lethal. An infected horse can spread the disease to other horses though body fluids before even symptoms present.
The virus is zoonotic which means it can transfer from animals to people. To date the cases of human infection were through contact with infected horses. There has been no case of transmission from bat to human or human to human.
Because of the fairly broad incubation period (5 to 21 days) it can be difficult to identify an infected horse.
- Frothy nasal mucus
- High fever
- Rapid heart rate
- Muscle spasms and twitching
- Balance difficulties
- Rapid deterioration and death
All 7 cases of human contraction resulted from “extreme” exposure to infected horses. Low levels of human-horse contact such as grooming and feeding have never resulted in disease.
- Cough and sore throat
Complications resulting from illness include encephalitis and septic pneumonia.
Horses in the early stages of the disorder may benefit from supportive therapies; fluids, anti-inflammatories, oxygen and pain management. The disease is fatal in approximately 75% of horses often within a few days following the onset of symptoms.
There is no specific treatment for infected humans except for monitored in a hospital environment for general medical support.
The Hendra vaccine has been available since November 2012 and shown to be the most effective way of reducing the risk of infection. The vaccination protocol requires a horse to be over 4 months of age with two initial vaccinations administered 6 weeks apart followed by a 6-month booster. Thereafter an annual booster is recommended.
Horse owners can take measures to minimize exposure for their horses and themselves. Guidelines suggest strategic placement of water and feed away from fruit trees that attract flying foxes; good hygiene and cleaning practices and isolate horses suspected of illness.
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Contact your local vet if you suspect your horse maybe infected. Australians are also encouraged to contact the Biosecurity Queensland 13 25 23 during business horse of 1800 675 888 24/7 Emergency for horses.
For human exposure contact your nearest public health unit or 13 HEALTH.
Photography Courtesy: (file photos)