Hendra virus, and the related Nipah virus, have now both been observed in livestock throughout North Eastern Australia and South East Asia which is a big problem as when this zoonotic virus makes the jump into humans it can be deadly. In Australia the biggest concern is for horses. All tallied up 75% of infected horses die or are put down due to Hendra infection and there have been 7 recorded cases of the disease jumping to humans, 4 people succumbed to the infection.
Whilst having the capacity to kill humans and horses yet another organism, the fruit bat, is thought to be the reservoir of infection. The viral infection is largely asymptomatic in the bats but results in the shedding of enormous amounts of virus in the bat urine and faeces which can be inhaled or ingested by horse resulting in infections. Horses can infect each other, probably through saliva, and the path to humans probably involves inhalation of aerosol from the horse. Transmission directly from bat to human has not yet been documented and it is unknown if this in fact even possible.
Jegarakshagan R. Gokul