What is Hendra virus?
Hendra virus is a virus first isolated in 1994 in an outbreak of respiratory and neurological disease in humans and horses in a Queensland suburb called Hendra. The natural reservoir of the Hendra virus is believed to be fruit bats (flying foxes), but the virus can infect horses and also humans, often with fatal consequences.
So far the virus has only been found in Australia and only a few humans have been infected.
Who is at risk of Hendra virus?
The humans that have been infected with the Hendra virus in Australia have been infected as a result of working directly with infected horses. They have been exposed to secretions and tissues from infected horses due to their work, such as veterinarians or horse trainers.
Transmission of Hendra virus
People who have been infected with Hendra virus appear to have been infected during close contact with sick horses. There has not yet been any human to human transmission of Hendra virus.
Hendra virus is not carried on the breath of horses which helps explain why it isn’t highly contagious. Fruit bats are known to secrete the virus in their urine, and it can be isolated from their blood and fetal and uterine tissues. No-one has yet been known to have been infected directly by bats.
Hendra virus symptoms
Most of the first human cases of Hendra virus had severe respiratory symptoms similar to flu. The infected horses also had severe respiratory disease. One of the infected people went on to develop encephalitis – an inflammation of the brain and subsequently died.
Hendra virus tests
Hendra virus can be identified by laboratory tests that examine serum, CSF (cerebrospinal fluid) or throat swabs from the person. These tests either detect antibody to the virus or isolate the virus itself.
Treatment for Hendra virus
There is an antiviral drug called ribavirin that has been shown in laboratories to be effective against the Hendra virus, but whether it works in clinical practice is uncertain. Researchers are looking at new treatments and perhaps developing a vaccine against this disease sometime in the future
What can be done about Hendra virus?
Properties such as horse studs where cases of Hendra virus arise are quickly quarantined. This effectively stops the movement of horses in and out of the property. Horses are kept under observation in case any further cases eventuate. People may still come and go from the property. Horses confirmed to have Hendra virus are destroyed and there may be a post-mortem to obtain further samples for testing.
People who may have come into contact with infected horses may be kept under observation.
The Hendra virus has been isolated in fruit bats as far north as Darwin and as far south as Melbourne, and research into its distribution is ongoing. Management of the disease will probably focus on preventing contact between fruit bats and horses and preventive measures to stop transmission from suspect horse cases to humans. There is now a vaccine for horses, which is the most effective way to prevent horses getting Hendra virus.