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Hendra Virus: What to Know

Medically Reviewed by Melinda Ratini, MS, DO on November 18, 2022

Hendra virus may not infect people that often, but it can be serious. Like SARS-CoV-2, the virus that causes COVID-19, you can get a dangerous respiratory infection. 

The Hendra virus infects large fruit bats, but it doesn’t hurt them. When horses come into contact with the bats’ bodily fluids, they can get the virus. Horses -- not bats -- can pass it on to people. 

 

Where Does Hendra Virus Come From? 

Large fruit bats, also called flying fox bats, can carry Hendra virus. Scientists say it can affect all four species of Australian flying foxes. Based on what scientists know, it doesn’t occur naturally in any other species. 

The virus is named after a suburb of Brisbane, Australia, where it was first found in horses in 1994. There have also been cases of Hendra virus passed on to dogs.

Hendra is known as a henipavirus, and it’s similar to Nipah virus, which also comes from bats. These viruses kill anywhere from 40% to all of the animals and people they infect.

Is Hendra Virus Only in Australia?

The virus has only affected horses in Australia. You’re not at high risk for it unless you live where those bats live and are exposed to horses there that may have been exposed. 

What Causes Hendra Virus Infection?

Here’s how bats give Hendra virus to horses: A horse may eat grass or hay that has been contaminated with bat urine or droppings. Horses might also eat food bats spit out or their birth waste. A horse can get the virus if it's exposed to any bodily fluid from an infected bat.

When a pathogen is transmitted from non-humans to humans, that’s called spillover. Humans get Hendra virus from horses, but they cannot get it from bats. The horse is the middle man. Though there are cases of Hendra virus in dogs, there’s no evidence dogs can give it to humans.To date, there are no cases of humans passing it to humans. 

In recent years, the bats have relocated closer to horses, which could explain why the virus seems to be on the rise. Researchers say environmental changes -- like deforestation and food shortages -- are forcing the bats from their homes to seek food in regions closer to horses.The bats’ stress levels may cause them to shed more of the virus. Scientists think they may be able to keep the bats in their original locations if they can restore those habitats.

 

Who Gets Hendra Virus Infection?

Hendra virus infection is very rare,  especially in people. More animals have gotten it compared to people since Hendra virus infection was first reported in 1994. As of 2013, the CDC reports only seven cases. There were 53 incidents in more than 70 horses as of 2015, the WHO reports.

You’re at risk if you are in Australia and go near horses who have been near where the bats live. You’re also at risk if you’ve been near infected horses or horses that may have had contact with flying fox bodily fluids. The highest risk is in those who’ve been in close contact with an infected horse,  like a veterinarian -- especially if they didn’t wear protective gear.

What Are the Symptoms of Hendra Virus Infection?

It takes about 9 to 16 days for the virus to show up in humans.  Common Hendra virus symptoms in humans include:

  • Fever
  • Chills
  • Sore throat
  • Runny or stuffy nose
  • Cough
  • Body aches
  • Headache
  • Fatigue
  • Vomiting
  • Diarrhea 

More severe symptoms include:

  • Meningitis (inflammation in the brain and spinal cord)
  • Encephalitis (inflammation of the brain) 
  • Convulsions 
  • Coma

How Do I Know if I Have Hendra Virus Infection?

If you have symptoms of Hendra virus infection and were in Australia, go to your doctor for testing.  You may need blood and urine tests, nose or throat swabs, or other tests. 

Doctors can do a blood test see if you carry antibodies to the infection, which shows you’ve had it. This is ideal for people who have been exposed.

Researchers recently identified a new variant of Hendra virus, or HEV. The variant is named HeV-g2.

 

How Do Doctors Treat Hendra Virus Infection?

Though rare, Hendra virus infection kills 1 out of every 2 people infected. That’s why it’s crucial to get treatment if you have been exposed. 

A specific treatment, like an antiviral medication, doesn’t exist. The drug ribavirin has worked in lab testing, but it’s not widely available as an approved treatment for people with Hendra virus infection. You may be hospitalized so doctors can treat your symptoms. 

Researchers are looking into using monoclonal antibodies to treat Hendra virus infection. 

 

How Do I Prevent Hendra Virus Infection?

If you are in Australia, you can:

  • Wash your hands if you’re around horses -- especially if you’re exposed to any of their bodily fluids.
  • Do not kiss the horse, especially if it’s sick.
  • Put a bandage on any cuts you have before you handle horses. 
  • Recognize any symptoms early.
  • Avoid ill horses.
  • Use personal protective gear if you’re in close contact with horses (mostly for vets).

People who handle horses need to take additional measures, like protecting horse food from exposure to bat fluids, isolating sick horses, reporting cases, and vaccinating horses. 

If you have been exposed to Hendra, do not donate blood or tissue until your doctor has cleared you of having Hendra virus. You shouldn’t donate if you’ve had Hendra virus infection.

Is There a Hendra Virus Vaccine?

Yes, but only for horses. The Equivac HeV vaccine is on the market. The Australian Veterinary Association recommends that horse owners give it to all their horses. There’s no vaccine for humans.

Show Sources

SOURCES:

Nature: “Pathogen Spillover Driven by Rapid Changes in Bat Ecology,” “Why Do Bat Viruses Keep Infecting People?”

Wildlife Health Australia: “Hendra Virus and Australian Wildlife Fact Sheet.”

NSW Health: “Hendra Virus Fact Sheet.”

Emerging Infectious Diseases: “Hendra Virus Infection in Dog, Australia, 2013.”

CDC: “Hendra Virus Disease,” “Nipah Virus,” “Novel Hendra Virus Variant Circulating in Black Flying Foxes and Grey-Headed Flying Foxes, Australia.”

American Association for the Advancement of Science: “What Makes Bat Viruses So Deadly?”

Genetics and Molecular Biology: “Zoonotic Spillover: Understanding Basic Aspects for Better Prevention.”

World Health Organization: “Hendra Virus Infection.”

Cell Reports: “Cooperativity Mediated by Rationally Selected Combinations of Human Monoclonal Antibodies Targeting the Henipavirus Receptor Binding Protein.”

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