At a glance
- Hendra disease is an extremely rare illness caused by the Hendra virus and has been reported in people and horses.
- Horses get sick with Hendra disease after contact with Australian flying fox bats or their fluids.
- People have been infected after contact with infected horses.
- There have only been seven cases reported in humans.
- Prevent infection with Hendra virus by avoiding sick horses.
What it is
Hendra virus was first identified during a 1994 outbreak of lung and brain disease in horses and people in Hendra, Australia. The virus is part of the same virus family (Paramyxoviruses) as Nipah virus.
Pteropus bats, or "flying fox" bats, are the animal that maintains Hendra virus in nature. The virus has been found in all four species of Australian flying foxes.
Flying foxes can infect horses with the virus when they bite the horses. Horses can also be infected if they are exposed to the urine, droppings, or saliva of an infected bat. Spread from flying foxes to horses is limited to coastal and forested regions in Australia (Queensland and New South Wales states). Horses can then spread the virus to people.
Hendra infections in people remain rare; only seven cases have ever been reported.
Signs and symptoms
Symptoms in people typically begin 9-16 days after they had contact with an infected horse. Hendra infection can cause lung problems with severe flu-like symptoms. In some cases, illness may progress to brain swelling (encephalitis).
Hendra infections are rare. However, it leads to death in more than half of people who get it (57 percent).
Exposure risks
People at highest risk are
- Those living in areas with Australian flying foxes
- Those in contact with horses potentially exposed to flying foxes
See where Pteropus bats live
How it spreads
Hendra virus can spread to people after contact with tissues or excretions of infected horses, like blood, urine, or birthing materials.
Horses may be infected after exposure to virus in the urine, droppings, or saliva of infected flying foxes. Infected bat urine or droppings can fall directly on the horse or in the food or water they're consuming.
To date, no spread between people has been documented.
Prevention
Hendra infection in people has only been linked to infection of an a "middleman" animal, or intermediate host, like horses. Early detection of infections in horses is an important way limiting future Hendra infections in people.
People in areas with Hendra virus or flying foxes can prevent illness with Hendra virus by:
- Avoiding sick horses
- Avoiding horses that may be infected with Hendra virus
If someone must have contact with an infected horse, they should use personal protective equipment, like boots, gloves, protective eyewear, mask or respirator, and gown.
There is a commercial vaccine licensed in Australia for horses. This could be beneficial for other animal species that may be at risk for Hendra infection and eventually people.
Testing
Laboratory tests can diagnose Hendra infection. These tests include detection of antibody by ELISA (IgG and IgM), real-time polymerase chain reaction (RT-PCR), and virus isolation attempts. The same tests can detect Nipah virus.
In most countries, Hendra virus should be handled in high- containment laboratories.
Hendra or Nipah virus infection can be diagnosed during the acute and convalescent phases of the disease. This can be done with a combination of tests including
- Detection of antibody in the serum or the cerebrospinal fluid (CSF),
- Viral RNA detection (RT-PCR) in the serum, CSF, or throat swabs, and
- Virus isolation from the CSF or throat swabs.
Treatment
The drug ribavirin has been shown effective against Hendra and Nipah viruses in laboratory studies. However, it's not clear how much help it would be in patients sick with Hendra infection.
An antibody drug that prevents Hendra and Nipah infection in people is in development in Australia. If it reaches final development, the therapy would be given to people who were exposed to Hendra virus and became sick.