Hendra virus

Hendra virus is a rare disease that can pass from an infected horse to a human. An illness that spreads from animals to people in this way is called a zoonotic disease. In the regions where it has been reported, the cases have all been in people who had close contact with infected horses.

Without prompt medical treatment, the complications of Hendra virus can be fatal.

There is no cure, human vaccine or specific treatment#

A vaccine for horses has been available since 2012, but there is no human vaccine and no specific medical treatment. The best defence is avoiding contact with an infected horse.

If one of your horses becomes sick, seek immediate advice from your veterinarian about whether the illness could be Hendra virus, and see your own doctor. Hendra virus is a different disease from equine flu, which is a highly contagious viral disease that infects horses but not people.

The virus was first identified in 1994 after a horse trainer and 14 of his horses died. A stable hand was also infected but recovered. It was named after the place where it first occurred. A small number of further human deaths have been recorded since, all linked to close contact with infected horses.

Symptoms in horses#

The clinical signs of Hendra virus in horses can be vague and non-specific. They may include:

• frothy nasal discharge and a high temperature
• rapid heart rate and difficult or rapid breathing
• sweating, muscle spasms and twitching, or muscle weakness
• balance problems, including an uncoordinated gait and head tilt
• apparent vision loss, aimless walking and rapid deterioration

Avoid close contact with a sick horse, and with any other animals that have had close contact with it, until the horse can be tested to find out whether it has the virus.

Symptoms in people#

Hendra virus tends to attack either the respiratory system (lungs) or the nervous system (brain). Symptoms in a person can include:

• fever and headache
• dry cough and sore throat
• breathing difficulties
• dizziness
• unusual sleepiness or confusion

Fatal complications have included severe pneumonia and encephalitis – severe brain inflammation and swelling that can lead to convulsions or coma.

Hendra virus is not highly infectious, so exposure does not always lead to infection. When infection does occur, the incubation period usually ranges from about five to 16 days, and occasionally up to 21 days. Current evidence shows the virus cannot be passed from one person to another.

How the virus spreads#

Scientists believe the natural reservoir (host) of Hendra virus is the fruit bat (flying fox), which appears to carry the virus without becoming ill and excretes it in its urine. Exactly how it is transmitted from bats to horses is not known. One theory is that a horse ingests pasture or fruit contaminated with infected bat urine, droppings or saliva. The virus in the horse’s body fluids – including blood, urine, saliva and nasal secretions – can then be passed to a person during close contact.

People at increased risk of infection include those who work closely with horses, such as:

• horse owners and stud workers
• veterinarians and veterinary assistants
• farriers, equine dentists and strappers
• feed delivery workers

Diagnosis and treatment#

To diagnose Hendra virus, a doctor may consider your medical history and lifestyle factors (such as your degree of contact with horses), carry out a physical examination, and arrange blood tests.

There is no cure or specific treatment. Care aims to ease symptoms and reduce the risk of complications while the person recovers, and may include hospital admission and close monitoring, fluids and medicines given into a vein, and life support such as mechanical ventilation if necessary.

A single confirmed human case of Hendra virus is treated as an outbreak. When an infection occurs, health and animal-health authorities work together to locate and control it and reduce the risk of further transmission. The virus is present in areas inhabited by fruit bats, which raises concern about possible spread where horses and fruit bats live close together.

Good hygiene is the best defence#

Suggestions include:

• Always wash your hands with soap and water after handling horses, and dry them thoroughly. Do not put unwashed hands near your eyes, nose or mouth.
• Clean used equipment between handling each horse.
• Avoid contact with a sick horse, keep it isolated from other horses, and seek immediate advice from your veterinarian.
• Wear protective equipment such as goggles and gloves if you must come into contact with a sick horse. Wear long sleeves and long trousers when handling sick horses, or whenever splashes of blood or body fluids onto clothing are likely (even from a well horse).
• Shower and change clothes as soon as possible after any contamination with a horse’s blood or body fluids, and wash the clothes before re-use.
• If you wear gloves when in contact with blood, body fluids or faeces, remove and dispose of them immediately afterwards and wash your hands.
• Avoid contact with secretions (including blood, urine, saliva or nasal secretions) even when a horse is dead, as the virus may still be active. Wash and dry any contaminated area of skin thoroughly with soap and water.
• Do not kiss horses on the muzzle or face.

Veterinarians or other workers who must handle a sick horse should wear full protective gear, including a face shield, respirator mask, non-permeable overalls, gloves and boots. Contact your local veterinarian for advice about vaccinating your horses against Hendra virus. Do not place water or feed troughs under trees or in other areas where bats may roost.

Contact with bats#

Evidence suggests Hendra virus cannot be passed directly from infected fruit bats to humans. However, it is important to avoid handling fruit bats because of the risk of a separate, serious disease closely related to the rabies virus that can cause fatal encephalitis. Bites, scratches or splashes of infected blood, saliva or urine into the eyes, nose, mouth or broken skin can cause infection.

Do not attempt to handle a sick or injured bat yourself. Report it to the appropriate wildlife or animal-health authority for referral to an authorised wildlife carer. Bat handlers and carers should be vaccinated with the rabies vaccine to protect against this related infection.

Key points#

• Without prompt medical treatment, the complications of Hendra virus can be fatal.
• There is no cure, human vaccine or specific medical treatment for Hendra virus.
• Symptoms in a horse can be vague, and symptoms in a person can include fever, breathing difficulties and confusion.
• People at increased risk include horse owners, stud workers and others who work closely with horses.

Where to get help#