What is Hendra Virus Infection?
Hendra virus is a very rare disease, confined to a small part of Australia, near Brisbane. This virus is spread from a type of fruit bat called the flying fox to horses. Horses who contract this disease can spread it both to other horses as well as to humans. Flying foxes with this virus show no ill effects from playing host, however, horses and humans are a much different matter. Approximately 75% of the equines infected with the hendra virus succumb to it within 48 hours, and somewhere around half of the humans infected will meet the same fate.
Hendra virus is a rare but deadly virus in Australia, spread by flying fox bats to horses. Infected equines can transmit the virus to other horses, or to humans.
Book First Walk Free!
Symptoms of Hendra Virus Infection in Horses
Symptoms in horses and humans are similar in nature, showing flu-like and respiratory symptoms first with neurological symptoms following:
- Abnormal gait
- Aimless walking
- Bad breath
- Dazed behavior
- Delayed blood clotting
- Difficulty urinating
- Head tilting
- Hot hooves
- Inability to rise
- Loss of appetite
- Loss of coordination
- Nasal discharge
- Pulmonary edema
- Rapid breathing
The hendra virus belongs to the family Paramyxoviridae and genus Henipavirus. There are a few other members of the henipavirus including the nipah virus and the cedar virus.
Nipah, like hendra, utilizes flying fox bats as it’s primary reservoir. The flying foxes transmit this virus to pigs which then spread it to humans. Only found in Bangladesh, this virus has an average mortality rate of around 74%.
This henipavirus has only been discovered in fruit bats to date but does not cause illness in animals that are susceptible to the hendra or nipah virus. The discovery of this virus may help lead scientists to develop a vaccine for its more dangerous cousins.
Causes of Hendra Virus Infection in Horses
Hendra virus is spread from several species of flying fox to horses, although the mechanism of transmission is still unclear. From there horses can spread it both to other horses and to people. This transfer appears to happen rapidly from horse to horse, particularly when the animals spend most of their time confined together in a stable or barn, but transmission to humans is slightly rarer. The hendra virus attacks the cells within the secondary host's body as well as causing widespread inflammation due to the activation of the immune system.
Diagnosis of Hendra Virus Infection in Horses
The speed at which this virus kills means that quite often it is diagnosed posthumously. Horses in the areas where hendra virus has been located should be isolated if any of the symptoms of hendra virus are displayed. Large animal veterinary professionals in areas where this disease occur are more at risk of contracting this disease due to their close work with equines, particularly if good standard hygiene practices are not maintained. Evaluation of the ill horse will most likely begin with a full physical examination including the standard biochemical panels and complete blood count tests.
Along with blood and serum samples, swabs should be taken from the nasal, oral, and rectal areas for complete testing. The hendra virus is fatal to over half of the humans who contract it, so blood tests that are being run should be subject to the highest level of caution, using biosecurity level 4 conditions to prevent the spread of the virus from horse to humans.
Treatment of Hendra Virus Infection in Horses
Equines who are in the early stages of the disorder may gain some protection from the ravages of the virus from supportive therapies: IV fluids could be given to prevent dehydration or imbalances in blood sugar and electrolytes, anti-inflammatories may be offered to both reduce inflammation and help to manage pain, and oxygen may be administered if the animal is having trouble breathing. Although treatment after infection may improve mortality, the sad truth is that this disease is fatal in approximately 75% of horses that contract it, and somewhere around half of the humans who are infected also succumb.
Although no vaccines have yet been created for human use, in November of 2012 an effective equine vaccine was developed and by 2014 over 100,000 horses had been inoculated against the disease. The best method for dealing with this virus is to vaccinate your horses against it if you live in an area near where outbreaks have occurred. This both protects the horse from ever contracting the disease in the first place, which prevents the spread to human hosts as well.
Recovery of Hendra Virus Infection in Horses
Fortunately, this disease is only spread by contact with fluids from an infected or recently dead victim of the virus, so there are steps that can be taken to prevent the virus from spreading to either humans or other horses. It is important to quarantine the horse from other horses, and the minimum number of caregivers required for treatment should be employed to avoid the risk of multiple exposures. Protective gear, such as rubber gloves, rubber boots, and a respirator and face mask, should be utilized both when treating a living patient or when performing a necropsy on a horse that has a known or suspected infection.