Hendra Virus - Sources, Transmission, Symptoms, Diagnosis, and Management

Introduction

Hendra virus, or Hendra henipavirus, belongs to the Paramyxoviridae family of viruses and is related to the Nipah virus. Both are considered to be different species of the genus Hepina. The virus got its name due to the respiratory outbreak among horses and humans caused by it in Hendra, Australia, in 1994. Bats (flying foxes) are considered to be the reservoir or storehouse of viruses.

What Is Hendra Virus Infection?

Hendra virus infection (HeV) is a zoonosis infection. Zoonosis is an infection that is transmitted from an animal to humans. HeV infection is a bat-borne infection.

How Common is HeV Infection?

Until 2013, infections caused by the virus remained rare worldwide. Hepatitis E infections show a seasonal pattern. The outbreak of Hepatitis E is more frequent between May and October.

Does the Hev Infection Follow Any Specific Geographic Distribution?

The Hendra virus's outbreak of infections follows a specific geographic outbreak. However, the Hendra and Nipah viruses belong to the same family. Nipah virus infections are more widely distributed worldwide, such as in Malaysia, India, and Thailand. However, the Hendra virus infections are more localized to the Australian belt, Okinawa, and southeast Asia.

How Is the Virus Transmitted?

The virus is transmitted by the transfer of the virus from the body fluids, such as the excreta, urine, etc., of the horse or fruit bats belonging to the Pteropodidae family and genus Pteropus (flying foxes). Therefore, people having close contact with infected horses are more prone to contracting the virus. However, no human-to-human transfer of the virus has been reported.

How Does the Virus Spread from Animals to Humans?

The virus is present inside the bat's bloodstream (viremia) for almost a week. The bat sheds the virus into the environment through body excretion. Humans and horses in close contact with the excretions acquire the virus.

Who Is More Prone to Getting the Hendra Virus?

The primary reservoir of the virus remains the flying fox bats and the horses. Hence, people closely associated with these animals for occupational or recreational purposes are at an increased risk of getting infected with the virus.

Where Is the Virus Found in Abundance Inside the Human Body?

The virus is present inside and can be recovered from various regions, such as the lungs, kidneys, spinal cord, upper respiratory tract, heart, and adrenal glands.

What Are the Signs and Symptoms of Hendra Virus Infections?

Hendra virus mainly causes infections that affect the respiratory system. Therefore, people experience

• Hemorrhage and edema of the lungs.

• Inflammation of the meninges (viral meningitis).

• Congestion.

• Patients may also suffer from neurological symptoms.

• Enlarged and edematous submandibular, bronchial, and sternal lymph nodes.

How Is the Hendra Virus Detected?

The diagnosis of patients suffering from Hendra virus infection takes place in a highly isolated environment to avoid contamination. The virus diagnosis is made when the patients are in the acute phase or recovering (convalescent) stage of the infection. The following methods detect the virus:

• Enzyme-linked immunosorbent assay (ELISA) is performed to detect the IgG and IgM antibodies formed inside the host's body against the virus.

• Real-time polymerase chain reaction (RT-PCR) also helps identify the viral genetic material.

• Laboratory investigations for RT-PCR and antibody detection are done by collecting the patient's serum, nasal and throat swabs, and cerebrospinal fluid.

• Stall-side tests using antibody-conjugated magnetic particles and quantum dots show promising results in detecting the virus.

• Virus isolation.

• Histopathological examination of the infected tissue with immunofluorescence staining.

How Is Hendra Infection Managed?

There is no specific cure for the infection. Therefore, the current treatment mainly aims to provide symptomatic relief and intensive care therapy. Ribavirin, an antiviral drug, is effective against the virus.

What Are the Complications Associated With the Hendra Virus?

In severe cases, Hendra virus infections can lead to death. The other complication of the virus is encephalitis (inflammation of the brain region).

What Are the Conditions That Are Similar to the HeV?

The conditions or infections that are to be ruled out before forming a confirmatory diagnosis of HeV are:

• Acute African horse sickness.

• Virulent equine influenza.

What to Do if a Person Gets Exposed to the Virus?

If a person gets infected with HeV, animal vaccines have been developed by the National Institute for Infectious and allergic diseases (NIAID). The vaccine works by neutralizing the antigens of the virus. Monoclonal antibody therapy has also been effective in neutralizing the virus in patients post-exposure to the virus.

How to Prevent Hendra Infection?

The infection caused by the virus can primarily be prevented by reducing exposure to the sources of the virus.

• People should avoid contact with horses infected with the Hendra virus infection.

• People who are in charge of the care of the infected virus should do so by wearing personal protective equipment (PPE).

• Avoid nuzzling or kissing the horse if it is sick.

• Cover cuts or abrasions on the skin before touching the horses.

• Wash the hands properly before and after handling the horses.

• Only a few people should take care of horses suspected of HeV infection.

• Healthcare workers and veterinarians should always use PPE while managing the animals.

• Till now, the commercial vaccine for Hendra has been available for horses only.

Is Hendra’s Infection Serious?

Infections caused by the Hendra virus are rare, but the fatality rate of the diseases caused by the virus is high, with a more than 57 % mortality rate.

What Are the Risk Factors Related to Hendra Infection?

People who are at enhanced risk are:

• Veterinary assistance.

• Strappers.

• Feed delivery merchants.

• Horse wonders.

• Stud workers.

What Is the Outbreak of Hendra Infection?

One confirmed case of this condition in a person is an outbreak. If an infection occurs, the commonwealth government and the state work together to locate the infection and prevent its spread. This condition is present all over Australia, where fruit bats are inhabited. The coexistence of fruit bats and horses has increased concern about the spread of the virus in the area.

Conclusion

The Hendra virus belongs to the Paramyxoviridae family and is closely related to the Nipah virus. It is primarily present in fruit bats and can be acquired by equines through direct contact with the bat's bodily secretions. It is transmitted to humans by horses or by bats themselves. HeV-infected patients show flu-like and neurological symptoms. The diagnosis of the virus is similar to that of the Nipah virus (RT-PCR and ELISA). There is no particular treatment for the infection caused by the virus. However, commercial vaccines are available for horses. Such vaccines for the prevention of infection in humans are under trial.