Hendra virus

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Hendra Virus

Equine Morbillivirus Pneumonia

Hendra virus is fatal zoonotic disease caused by infection with the hendra virus (HeV), formally known as equine morbillivirus. It is a concern for horses living in Australia. HeV causes infection in mainly horses and, rarely, in humans and dogs. Hev is a paramyxovirus of the genus Henipavirus, subfamily Paramyxoviridae. HeV was first identified during an outbreak of acute respiratory disease in 21 Thoroughbred racehorses living in the Brisbane suburb of Hendra, Australia, in 1994. The trainer and stable hand also became infected and died. In 1995, a third human case occurred during a necropsy examination of two of the horses that had died as a result of the Hendra virus. Since then, there have been eleven outbreaks confined along the east coast of Australia, involving the death of at least 51 horses. Horses are the intermediate hosts for transmitting the infection to humans through close contact during care of sick horses or during necropsy and/or handling of dead infected horses.

Clinical signs of Hendra Virus


Hendra virus causes a wide range of clinical signs in horses. It should be considered a possible cause of any sick horse with an illness of an unknown origin, who has progressive signs leading to rapid deterioration in health. Signs of hendra virus in horses have a rapid onset and progressively worsen fast. They may be general at first and often include signs related to the respiratory tract and/or nervous system. General signs include:
  • Depression
  • Frequent weight shifting between legs
  • Fever up to 41°C (105.8°F)
  • Increased heart rate
Respiratory tract signs include:
  • Rapid breathing
  • Difficulty breathing
  • Nasal discharge upon death which can be initially clear, progressing to stable white froth or stable blood-stained froth.
Nervous systems associated with Hendra virus include:
  • Aimlessly walking in a dazed state
  • Head tilting
  • Circling
  • Wobbly gait
  • Apparent loss of vision in one or both eyes
  • Muscle twitching
  • Inability to rise
  • urinary incontinence

How the Virus is Spread


Fruit bats (Pteropus species), also known as flying foxes, are the natural reservoir host responsible for spreading this virus. The exact mode of HeV transmission between flying-foxes, or flying-foxes to horses has not yet been definitely determined. Hendra virus is transmitted two ways:
  • Infected flying foxes to horses - making it important that horse food and water containers are not placed under or near fruiting or flowering trees.
  • infected horses to humans and other animals -
sick horses must be isolated.

Virus Life Cycle


Hendra virus has an 4-16 day incubation period. The clinical course of the disease is typically short, with most horses dying within 48 hours of initial onset of clinical signs. Hendra virus will not survive for longer than several hours to days outside of the animal host.

Symptoms

Sudden onset
Fever up to 41°C (105.8°F)
Depression
Loss of appetite
Cyanosis
Copious frothy nasal discharge
Shallow respiration
Facial swelling
Ataxia
Disorientation
Hypersensitivity
Head pressing
Head tilt
Circling
Facial paralysis

Diagnosis

  • History
  • Clinical signs
  • Physical exam
  • Virus isolation
  • PCR
  • ELISA
  • SNT
  • Antigen detection

Support

Therapies

TherapiesDetails
Report diseaseHendra is a reportable disease, meaning that if you suspect that your horse has this disease, by law you need to report it to your veterinarian, or a state or federal veterinarian.
Euthanasia

Prevention

  • Vaccination
  • Place all feed and water containers under cover.
  • Try to bring horses into covered enclosures or enclosed paddocks with no trees at night to reduce potential contact with flying fox colonies.
  • Remove horses from paddocks where trees attract flying foxes or fence off trees to prevent horses grazing underneath.
  • When planting trees on your property do not plant trees that attract flying foxes in or near horse paddocks. These include trees with soft fruits for example, figs and stone fruits such as peaches, loquats, and mangos.
  • Seek veterinary advice before bringing any sick horses on to your property.
  • If you have a horse that you suspect of having Hendra, do not move any other horse off the property until given the all clear by the proper authorities.
  • Keep any sick horses isolated from people and other animals.
  • Plan a quarantine area on your property where sick horses can be isolated.
  • Remember to thoroughly wash your hands after and between handling individual horses to prevent the potential spread of Hendra virus infection.

Prognosis

Poor, most horses die within 48 hours of the onset of clinical signs, or often found dead.

Scientific Research

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