Hendra Virus Infection

Hendra Virus Infection – Causes, Symptoms, Diagnosis, Treatment

Hendra virus infection is a rare infection in horses as well as humans. The zoonotic disease is passed from an infected horse to an individual. So, infected horses are the main transmitters of the disease in humans while the horse suffers the infection from fruit bats. The outbreak occurred in Western Australia in people who came in close contact with the infected horses. The condition requires immediate medical attention. Without proper supportive care, the virus can destruct your life. You can suffer from fatal complications due to the infection. Unfortunately, no cure is available for treating the condition.

While no vaccine is available for humans to prevent the disease, horse owners can try the vaccine for horses. To prevent the disease, the best defense mechanism is to avoid contact with the infected horse. The horse owners need to report the case of their sick horses and seek medical attention from veterinarians. It is to detect the presence of HeV (Hendra Virus) immediately. While you can confuse the condition with equine flu, they are different. Equine flu is highly contagious that affects horses and not people. Read ahead to know more about the virus and its effects.

About Hendra Virus

The world came to know about HeV during the outbreak in a large racing stable in 1994. The virus affected several horses in the Hendra suburb stable, Brisbane. Flying foxes commonly known as fruit bats are the natural host for HeV. The virus spreads from the droppings or saliva of fruits bats to the horses, horses to horses, and finally from the horses to people. From its discovery in 1990, veterinarians have diagnosed more than ninety horses with the infection. Unfortunately, the horses have met a tragic end as the animals either died or euthanized. Many people (several hundred) became expose to HeV through infected horses. But, only seven people suffered the infection. It is attributed to high levels of exposure to the horses affected by the infection. Among the seven, four people died (until 2009).

Hendra virus infection

Dogs with evidence of exposure have shown no symptoms (asymptomatic).  During the investigation, it came to light that the dogs contracted the infection due to the contact with the infected horses on properties. The testing, as well as research, indicates the absence of transmission of Hendra virus in other insects and animals. So, the infection does not occur naturally in other animal species.

Symptoms Of Hendra Virus Infection

You may not see the signs associated with the infection overnight. After the exposure to an infected horse, you can see the symptoms appear within five to twenty-one days. The signs associated with HeV infection varies in humans and horses. So, you can see the following symptoms due to the infection:

Signs In Human

Individuals who come in contact with infected horses more can suffer from the following issues:

Influenza-Like Condition

People who catch the virus from an infected horse can suffer from influenza-like symptoms:


The above-mentioned symptoms may accompany with encephalitis. Inflammation of the brain can occur separately also. So, due to the condition, infected people can suffer from signs like:

  • High fever
  • Headache
  • Drowsiness
  • Convulsions
  • Coma

Signs Of Hendra Virus Infection In Horses

Signs Of Hendra Virus Infection In Horses

HeV infection in horses can trigger a wide range of signs. You cannot recognize it at first. But, the initial signs of fever can indicate some problems. So, pay close attention to other symptoms like:

  • Aimless walking
  • Abnormal gait
  • Congestion
  • Bad breath
  • Delayed blood clotting
  • Dazed behavior
  • Hoot hooves
  • Difficulty urinating
  • Loss of appetite
  • Head tilting
  • Loss of coordination
  • Pulmonary edema
  • Twitching
  • Nasal discharge
  • Rapid breathing
  • The complications can escalate and result in the death of the horses. So, prompt detection is necessary.

 Complications Due To Hendra Virus Infection

Without early intervention, the infection can cause serious health complications. HeV tends to attack the lungs or brain. People in Australia who have suffered the infection have experienced the following complications:

Septic Pneumonia

When the virus attacks the respiratory system, it results in lung infection. So, you can develop pus in the lungs. It leads to abscess formation in the lungs and ultimately results in lung tissue destruction. The severe condition is referred to as septic pneumonia.


HeV can infect the brain and spinal cord. It results in severe inflammation and swelling. So, you can develop encephalitis. The condition leads to convulsions or seizures. Ultimately, the patients enter a coma.

The Spread of Hendra Virus Infection

Hendra virus infection is not contagious. So, all people exposed to the virus may not suffer from the infection. People who get infected see the signs of infection after a few days or weeks. The incubation period of HeV varies greatly. So, it ranges from five to sixteen days or more (up to twenty-one days). The virus does not spread from one person to another. It usually transmits from fruit bats (flying fox) to horses and from the horses to humans. The fruit bats act as the host or reservoir for HeV. The fruit bat can carry the virus without suffering any complications. It excretes HeV through its urine, which affects horses.

Mode Of Hendra Virus Transmission

The exact mode of transmission remains unclear. But, the fruit bats spread the virus to horses. It happens when the horses consume water or food contaminated with the saliva/droppings of flying foxes carrying HeV. The infected bats can pass the virus through their saliva or feces. So, when the horses come in contact with such contaminated items, they suffer from the issue. Humans contract the virus when they come in direct contact with the infected horse’s body fluid like blood products or nasal secretions. For humans to get the infection, it requires high levels of exposure. Therefore, it occurs only in people who come in close contact with horses. So, veterinarians and stable workers can face the risk of exposure. People having low-level contact with the horses like feeding or patting them face less risk. There is no conclusive evidence to suggest the spread of HeV from human to human.

Transmission In Confirmed Hendra Virus Infection Cases

Hendra Virus Infection In the seven confirmed cases of Hendra virus infection in humans, high levels of exposure to blood and/or respiratory secretion from infected horses resulted in the condition. So, people who failed to use personal protective equipment (PPE) while assisting the postmortem examination of the dead animals received the infection. Others exposed themselves to HeV when they came in contact with the respiratory secretion or while performing veterinary procedures without using PPE. Other people who have reported similar contact with horses infected with HeV showed no signs of infection. The blood tests of such people show no evidence of infection. These groups of people received lower level exposure. So, people who performed tasks like grooming, patting or feeding never developed the infection, They never showed any evidence of infection in their blood tests.

Among the confirmed cases, no evidence points towards human to human HeV transmission. So, people who came in contact with an infected person never showed any evidence of HeV infection. It includes the following:

  • Health care workers
  • Close family members
  • Caretakers
  • No evidence suggests other direct transmission modes like the following:
  • Flying foxes (fruit bats) to humans
  • From the environment to humans
  • Dogs to human
  • From humans to horses
  • No evidence suggests the spread of HeV through the air. So, no evidence of airborne spread (due to tiny particles suspended in air) exists.

Risk Factors Associated With Hendra Virus Infection

Not all people coming in contact with infected horses suffer from the infection. A certain group of individuals who have high exposure to HeV experience the condition. So, people at risk of the Hendra virus infection include:

  • Farriers
  • Veterinarians and their assistances
  • Equine dentists
  • Feed delivery merchants
  • Strappers
  • Stud workers
  • Horse owners

So, the above-mentioned people need to see a doctor immediately if they experience signs.

Diagnosis Of Hendra Virus Infection

When you suspect the infection in horses or humans, they need prompt medical attention. The virus can cause fatal effects for the horses and trigger severe complications in humans. So, the different methods to diagnose the problem includes:

Diagnosing Hendra Virus Infection In Horses

Hendra virus infection can kill the horse at an alarming speed. So, in most of the cases, the viral infection is detected posthumously. To avoid the spreading of HeV, it is important to isolate the horses in the areas where the virus presence is detected. The horses need isolation when they exhibit symptoms associated with the condition. To avoid the transmission of HeV while closely working with the animals, everyone must follow high standard hygiene practices. The doctor evaluates the condition of the sick horse with the following tests:

  • Physical examination
  • Complete blood count test
  • Standard biochemical panels

Diagnosing Hendra Virus Infection In Humans

The diagnostic test to detect HeV includes the following:

  • Check Medical History
  • Understand Lifestyle Factors (like knowing the degree of contact with the horses)
  • Physical examination to check the signs

 Blood Tests

You need to provide a sample of your blood to the lab for testing. The pathologists can diagnose HeV using several tests like:


Enzyme-linked immunosorbent assay can detect the antigens linked to the Hendra virus infection. It is the widely used detection method to find the presence of the virus in humans.


The reverse transcription-polymerase chain reaction is a blood test that combines the amplification of HeV virus DNA and reverses transcription of RNA into DNA. It uses the polymerase chain reaction to find evidence of the virus.

Virus Isolation

The test isolated HeV from the blood sample provided to conclusively identify it.

Throat Swabs

A sample from your throat is collected by the technicians for testing. The throat swab can detect the presence of HeV.


Testing the sample of cerebrospinal fluid in the lab can reveal the presence of Hendra virus infection.


Sending the sample of the infected tissue for biopsy can reveal the presence of HeV conclusively.

Treatment For Hendra Virus Infection

When the horse or people who come in contact with Hev exhibit the signs associated with the condition, it is important to seek medical help. The treatment for viral infection are:

Equine Treatment For Hendra Virus Infection

If you have spotted the signs of Hendra virus infection in your horse early, then simple supportive treatment offers protection from the complication caused due to the virus. So, your veterinarian offers the following options:

  • To prevent imbalances in blood sugar, dehydration or electrolyte issues, provide IV fluids.
  • Anti-inflammatories are offered to manage and reduce inflammation.
  • If the animal experiences breathing trouble, oxygen is administered.

Supportive treatment only improves mortality in the early stages of infection. While such early intervention can help horses suffering from early signs, for severe cases, no treatment offers relief. Unfortunately, the majority of the horses (75%) who suffer from the infection succumb to it.

Treatment For Humans

Since no specific cure is available for the condition, you only have treatment to ease the symptoms. The supportive treatment also reduces the risk of complications when you recover from the infection. It is important to see an infectious disease specialist for accessing treatment for the condition. So, people who face high exposure risk of HeV need to get treatment. People who come within five meters of the suspected or infected horse need evaluation. It is also important to see a doctor when you come in contact with body fluids, feces or other contaminated surfaces. The treatment options for the condition are:

  • Getting treated in the hospital after admission. The doctor can keep a close watch on your condition and suggest the necessary treatment.
  • You get fluids and drugs intravenously to ease the symptoms associated with the infection.
  • In severe cases, life support is necessary. So, patients suffering from infection need mechanical ventilation.

Hendra Virus Infection Outbreak Control

Hendra Virus Infection Outbreak Control
Fruit Bats

Even one confirmed case of Hendra virus infection in a human is regarded as an outbreak. The state and Commonwealth government in Australia, work as a team to manage the infection during an outbreak. The goal is to locate and control the infection from spreading. So, it helps contain the infection. While other parts of Australia have not experienced the outbreak, the southern states of Australia have enhanced concern about the disease. The fruit bats in southern states have increased at an alarming rate, which has raised concerns regarding the spread of the virus.

Preventing Hendra Virus Infection

Unfortunately, no vaccine is available to stop the virus from affecting a person. So, you need to take steps to prevent its infection. People who work closely with horses need to take preventive measures to stop the Hendra virus infection. Good hygiene practices can offer the best defense mechanism against the virus. Here are some of the preventive measures you can adopt in your life:

Vaccination For Hoses

While no vaccination is available to prevent Hendra virus infection in humans, a registered vaccine for horses can prevent transmission. So, keeping the horses safe from the viral infection can reduce the infection in humans. It can prevent the virus (HeV) from infecting susceptible humans and other animals. But, the vaccination is not 100% effective as some vaccinated horses have suffered from the infection. If you are a horse owner, then discuss the options available for your horses with the veterinarian.

Wash Your Hands

Your hands can attract viruses or bacteria from any surface. From your hands, it reaches your mouth and your body. So, always wash your hands with soap and water after handling horses. Dry your hands thoroughly. Never put your unwashed hands near your mouth, nose, or eyes. It is because the virus can enter the body through these parts.

Clean Equipment

To prevent any spread of infection, you need to clean every equipment used on the horses every time. After handling each horse, it is important to clean them to eliminate the possibility of transmitting the infection.

Avoid Contact

People who work with animals, especially horse need to maintain caution while coming in contact with them. You need to follow the pointers suggested below to avoid transmission of HeV:

  • If you work with horses, keep them away from a sick horse. Avoid direct contact with them and keep the sick ones isolated from the other horses.
  • Contact a veterinarian to get the necessary advice to detect the problem with the sick horse.
  • Avoid coming in contact with secretions like urine, blood, saliva or nasal fluids from the horse (sick or horse). The virus continues to stay active even after the death of the horse.
  • Coming in skin-to-skin contact with horses can put you at risk of infection. So, refrain from kissing the horse on the side of the face and muzzle.
  • If you come in contact with secretions of the horse, then you need to wash the contaminated area thoroughly using soap and water. See a doctor as early as possible.


You need to wear PPE (personal protective equipment), which forms a tough barrier between the infectious agent and the person. So, you need to use the following items:

Rubber Boots

Using rubber boots will protect your legs from coming in contact with body fluids or secretions from the horses.


You need to wear a splash-proof overall to protect yourself from blood or other contaminated items from the infected horse. So, shooed long-sleeved dress with a hood or disposable overalls with an apron (splash-proof/impervious).

Disposable Gloves

Disposable Gloves
Source: Amazon.com

Wear nitrile gloves (disposable impermeable gloves) to prevent coming in contact with feces, blood, or body fluids. After coming in contact, remove and dispose of the gloves. Wash your hands immediately.

Shield To Protect Face

You need to wear safety eyewear or face shield to protect against facial splashing. It will prevent the spread of infection through your eyes or mouth.


To avoid inhaling HeV, you need to use a respirator to ensure proper breathing. It will avoid inhaling the virus through your nose.
Maintain the protocols associated with PPE. So, you need to shower to remove any contamination in your body due to body fluids or blood of the horse. Also, put your clothes in wash before using it again. Try to replace or repair the tools used for PPE. It will minimize the risk. You need to ensure all the items you use are working well. Using clean and hygienic safety tools will protect you. It is also important for people at high risk of exposure to use the PPE equipment.

Avoid Feeding Horse At High-Risk Areas

Bats infect the horses with HeV. Therefore, try not to place water or feed for the horse in areas with, which faces a high risk of roosting of the bat.


Hendra virus is a potentially serious infection requiring immediate medical attention. It transmits from flying foxes to horses. Queensland in Australia suffered the most due to the infection. Four people died due to the infection. While Western Australia remained unharmed due to the virus transmission, evidence showed several flying foxes in northern WA exposed to the virus. People who work with horses like veterinarians, their assistants, trainers, etc. must give utmost importance to their safety. So, it is important to assess the risk of infection before coming in close contact with horses. Following PPE protocol can keep their health safe. In the case of exposure, getting necessary help from the doctor will help prevent severe complications.

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