What is Hendra Virus?

Hendra virus is a rare disease that can be passed from an infected horse to a human. This type of illness is called a zoonotic disease. The cases reported in Australia 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 or specific medical treatment for Hendra virus and a vaccine is still in the developmental stage. The best defence is avoiding contact with an infected horse. If one of your horses gets sick, seek immediate advice from your veterinarian and see your doctor.

Hendra virus is a different disease to equine flu, which is a highly contagious viral disease that infects horses but not people.

History

Hendra virus first emerged in Australia in August and September 1994 when 13 horses died in the Brisbane suburb of Hendra (hence the name) and two horses died in an apparently unrelated outbreak in Mackay.
In Hendra, the horse Drama Series became the first recorded death from the virus and two people became infected after contact with the mare. One of them, prominent horse trainer Vic Rail, died as a result.
In October 1995, a Mackay farmer, Mark Preston, 35, became the third person to be infected with the virus and he also died as a result.

It was only after Mr Preston's infection and death that authorities discovered the initial August 1994 infection of two of his horses and made a retrospective diagnosis.
Since 1994 there have been 13 outbreaks of the disease - six people have become infected and four people have died.

Vet Dr Ben Cunneen, 33, became the third person to die when he caught the virus from infected horses at a veterinary clinic in Redlands, on Brisbane's southern outskirts in August 2008.
Another outbreak at a Cawarral property near Rockhampton in central Queensland in August 2009, also killed four horses and claimed the life of vet Dr Alister Rodgers, 55.
The mortality rate for horses is extremely high, with 70 per cent of infected animals dying from the virus.

Symptoms in Horses

In Australia, Hendra virus occurred in people who had close contact with infected horses. The symptoms in a horse can include:

• Frothy nasal mucus

• High temperature

• Rapid heart rate

• Sweating

• Muscle spasms and twitching

• Muscle weakness

• Balance difficulties.

Symptoms in Humans

The symptoms of Hendra virus infection in a person can include:

• Fever

• Headache

• Dry cough

• Sore throat

• Breathing difficulties

• Dizziness

• Unusual sleepiness

• Confusion.

Possible complications

Hendra virus tends to attack either the respiratory system or the nervous system. In Australia, the fatal complications have included:

• Septic pneumonia – severe lung infection involving pus, abscesses and destruction of lung tissue

• Encephalitis – severe brain inflammation and swelling which can lead to convulsion or coma.

Spread of infection

Hendra virus is not particularly infectious, which means that exposure doesn’t always lead to infection. If infection does occur, the incubation period usually ranges from about five to 15 days. Evidence suggests that the virus cannot be passed from one person to another.

Scientists believe that the ‘reservoir’ of the Hendra virus in Australia is the fruit bat (flying fox), which appears to carry the virus without suffering any ill effects. Exactly how it is transmitted from bats to horses is unknown. One theory is that the horse ingests food or water contaminated with infected bat urine. The virus in the horse’s body fluids (including blood, urine, saliva or nasal secretions) can then be transmitted to a person during close contact.

Risk factors

People at increased risk of infection include:

• Veterinarians

• Farriers

• Equine dentists

• Strappers

• Feed delivery merchants

• Horse owners and stud workers.

Diagnosis

Tests used to diagnose Hendra virus may include:

• Medical history

• Lifestyle factors – for example, degree of contact with horses

• Physical examination

• Blood tests

• Biopsy of infected tissue.

Treatment

Currently there is no cure or specific treatment for Hendra virus. Treatment aims to ease symptoms and reduce the risk of complications while the person recovers. Options may include:

• Hospital admission and close monitoring
• Drugs and fluids given intravenously
• Life support if necessary – for example, mechanical ventilation.

Outbreak control

One confirmed case of Hendra virus is considered an outbreak. If an infection occurs, State and Commonwealth government departments work as a team to locate and control the infection to reduce the risk of transmission. To date, Victoria has not had a single animal or human case of Hendra virus. However, the increased spread of fruit bats to the southern states of Australia has raised concern of a related spread of the virus.

Prevention

There is currently no vaccine to protect against infection. Good hygiene practices are the best defence. Suggestions include:

• Always wash hands with soap and water after handling horses. Dry hands thoroughly.

• Don’t 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 in contact with a sick horse. Wear long sleeves and long trousers.

• Avoid contact with secretions (including blood, urine, saliva or nasal secretions) even when the horse is dead – the virus may still be active.

• Wash and dry the contaminated area thoroughly with soap and water if you come in contact with secretions. See your doctor.

• Veterinarians (or other workers) who must handle a sick horse should wear full protective gear including face shield, respirator mask, non-permeable overalls, gloves and boots.

• Don’t place water or feed troughs for horses under trees or in other areas where bats may roost.

Lyssavirus infection

Evidence suggests that the Hendra virus cannot be passed directly from infected fruit bats to human. However, it is important to avoid handling fruit bats because of possible infection with the lyssavirus, a serious disease that can cause fatal encephalitis. Bites, scratches or splashes of infected blood, saliva or urine into the eyes or nose can cause infection.

Report a sick or injured bat to a wildlife service rather than handling the animal yourself. All bat handlers or carers should be vaccinated with rabies vaccine to protect against Australian bat lyssavirus infection.

Where to get help

• Your doctor

• Veterinarian

• Community health centre

• Wildlife service

• Communicable Disease Prevention and Control Unit (Public Health Branch), Department of Health Victoria Tel. 1300 651 160

Things to remember

• Hendra virus is a rare disease – the very few reported cases in Australia were in people who had close contact with infected horses.

• There is no cure, specific treatment or vaccine.

• The best defence against Hendra virus is to avoid contact with an infected horse.