How do horses get equine influenza?

Question

The outbreak in Australia is just horrible but I was wondering how a horse actually catches it and do they die from it?

Answer 1

What the other posters said is basically correct, although I'd like to add a couple of things to it.

First thing, the vaccine for equine influenza is not 100% effective, and as with human flu vaccinations, it has to be administered on an annual basis.  Here in the US, even though vaccination is a fairly standard procedure, we still have outbreaks.  There was a serious outbreak on the eastern seaboard area last year, and there have been outbreaks here on the west coast, in the Northern California area.  Generally when an outbreak occurs, the authorities immediately put a ban on movement of horses from the affected area.  This can work a real hardship on people in racing, because they can't move horses from racetrack to racetrack or from training centers.  While the older horses that get equine influenza do generally recover, it takes time and of course it completely disrupts a horse's training schedule.

In Australia, they are just starting the breeding season and virtually all of the shuttle stallions (horses that shuttle between Northern Hemisphere and Southern Hemisphere farms) are stuck in the quarantine stations.  These stallions were in quarantine for three weeks in their country of origin before shipping to Australia and New Zealand, and have been in quarantine there for another three weeks;  the quarantine facilities are not set up to hold horses for long periods of time, so this is not a good situation.  The stallions involved are worth tens of millions of dollars.

This outbreak is devastating to the Australian bloodstock industry.  I don't know how things are going to end, but this will almost certainly result in changes in the practice of shuttling stallions between hemispheres-- possibly requiring longer quarantine periods or other measures that might make shuttling economically unfeasible.

Here's a link to one of the articles about the current outbreak:

http://www.abc.net.au/news/stories/2007/...

My heart goes out to the people in the horse industry down under.  This is really a catastrophe for them.

Answer 2

The virus can be spread easily from horse to horse as a result of droplets and also from nasal discharge and from things like infected brushes and rugs. The disease is very contagious and there is almost 100% infection rate in a population that has been previously unexposed to the virus.

Answer 3

The previous answer is very good, and all that I would add is that EI can also been tranported by humans (on their clothing, shoes, etc).

Whilst still serious, EI will generally make a horse feel ill for about 3-4 weeks before making a full recovery.  90% of adult horses will recover without any problems, although older horses and those that already have repiratory problems may not.

Approx 40% of foals that contract EI will die

In Europe and North America 95% of horses are vaccinated against EI so it is very rare to see an outbreak - ALL racehorses and bloodstock are vaccinated.

The main problem in Australia is that because they have never had an outbreak of EI, horses are not vaccinated as standard.  Therefore an outbreak is much more serious as EI has a 100% infection rate in unvaccinated horses.

Answer 4

Equine Influenza

Equine influenza is a major virus disease that causes flu like symptoms in horses and is from the group of viruses that causes flu in humans. This is a major viral disease present throughout Europe, North America and parts of Asia.

What is the incubation time?

Most horses exposed to the virus will show signs within a period of 1-5 days.

What are the signs of influenza?

Equine influenza appears similar to a range of other viral respiratory diseases. Viruses that are responsible for coughs and colds in Australia include Equine Herpesvirus, Equine Rhinovirus and Equine Adenovirus. Most of these viruses produce rather mild signs which include a discharge from the nose and coughing. Equine Influenza produces more severe symptoms with horses developing a fever and a dry hacking cough. Horses become ill and are reluctant to eat or drink for several days but usually recover in 2 to 3 weeks.

How is influenza virus spread?

The virus can be spread easily from horse to horse as a result of droplets and also from nasal discharge and from things like infected brushes and rugs. The disease is very contagious and there is almost 100% infection rate in a population that has been previously unexposed to the virus.

Can it be prevented and treated?

Because it is a virus, there are no drugs that influence the outcome of the disease. However many horses develop secondary infections with bacteria which can lead to pneumonia and other problems. Good nursing care and if necessary, antibiotics to deal with bacterial illness associated with the disease are important parts of treatment. The most important part of dealing with this illness is effective vaccination. Reasonably effective vaccines are now available featuring the two most important types of this virus but horses need to be vaccinated 2-3 times per year to ensure their immune status.

The most likely way that this disease could be introduced into Australia is through an imported horse and horse owners should be aware of this potential if there are any horses introduced onto farms or into stables. The most likely signs will be the rapid spread of a severe respiratory flu like disease which is more severe than the usual virus problems