Vaccinating Against EI

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6th September 2007

Vaccinating Against EI
 
There has been a lot of debate on whether or not to vaccinate against Equine Influenza.  Below are some interesting pieces on the topic. 
 
The first is from www.breednet.com.au , an interview by Tara Magdwick with Dr Tim Roberts.  It was Dr Roberts who first alerted authorities to the outbreak at Centennial Park in Sydney.

From Dr Tim Roberts BVSc MRCVS, Centennial Park Vet Practice - I realise everyone is trying to do the best for their horses as they face the challenge of Equine Influenza recently introduced into Australia.

NSW and Queensland are bearing the brunt of this tragedy and it is frustrating to watch some getting on with their business in other unaffected areas while others are tantamount to being in the “sin bin”.

This is all a repeat of the 1986 South African outbreak where Natal kept racing while the rest of South Africa watched and attended “ghost meetings”.

One might ask why can’t we just vaccinate the horses that are unaffected and just get on with it?

Vaccination was the only approach left to us in 1986 as the virus was widespread and racing throughout the breeding stock in the Cape, Transvaal and Orange Free State decimating foals and the weak.

Vaccination was decided upon because by the time it was diagnosed the virus was well disseminated across the country and rampant in the uncontrolled horse population in the native lands scattered throughout the country.

Small pockets of isolated horses were vaccinated and eventually a compulsory nationwide vaccination policy was adapted.

Containment was never an option in South Africa as it is in this outbreak in Australia.

While the benefits of vaccination are protection if the correct vaccine is used, you still need the absolute minimum of four weeks to achieve a suitable level of protection.

This involves shortening the recommended vaccination protocol but it does work.

I personally vaccinated an isolated population of 1000 horses at the Vaal Racecourse on the Transvaal / Orange Free State Border at two week intervals and achieved protection by the time the virus arrived four weeks after the vaccination program was initiated.

Isolation was odds on to fail at Randwick Racecourse as there was too much interaction in the Randwick and Kensington areas between people and the distance was a serious concern.

Having watched this virus in action in a naive population it was unrealistic to even imagine Randwick could have been protected. I must say Randwick trainers and their staff did a remarkable job to keep it out for five days, I applaud them for their efforts.

David Payne who experienced the outbreak in South Africa stopped training almost immediately and prepared for the inevitable when the EI confirmation in Centennial Park Equestrian Centre (CPEC) was announced.
In 1986 David and I had watched this virus travelling at 6km per day across the Transvaal towards the Orange Free State so the stones throw from CPEC was a mere hop.

The benefits of containment over vaccination far outweigh a disruption to racing for three months.

If we chose vaccination or containment the time frame is the same as we still need to eliminate the virus from the affected horses.

If we can contain and eradicate the virus we will be able to return to an EI free status.

Free movement of horses between the states and our greatest equine trading partner across the Tasman will again eventually permit unrestricted movement. (Provided we let their apples in.)

As containment is the policy of the Austvet Plan we are all obligated by law to follow this policy.

A lot of very capable and highly experienced people devised this response and set the protocols of dealing with this specific disease. Like all plans of action everyone must pull in the same direction to achieve a successful outcome.

Random vaccination of horses would complicate this containment plan and make it far more difficult to evaluate the status of horses and the spread of the virus.

There are a number of horses in the population that are legally vaccinated, this can complicate the issue but as long as these horses have a recorded vaccination history then they can be dealt with appropriately.

These horses will need extra testing as they can become reservoirs “much like roots burning underground in a bush fire” and “flare ups” could occur if these horses are quietly harbouring EI and are moved into naïve populations.

So having a vaccination history will most likely be a disadvantage if a movement permit is sought in the near future.

What we certainly do not need is people vaccinating their horses without approval from the Department of Primary Industries.

It is illegal to vaccinate horses randomly, I believe large fines apply and it is certainly
pointless in the face of an imminent outbreak. Worst of all it confuses the immunological picture which is highly irresponsible because it will cloud the issue when we are trying to clear affected areas of and reinstate them as EI free after this outbreak.

Random vaccination in the face of an outbreak that is being contained is tantamount to biological sabotage anyone adopting this policy unilaterally should be brought to account and face the penalties that are legislated.

If at some point we do decide to vaccinate it should be done in an orderly and systematic method with the correct strains of killed virus. We must all work together in this crisis because if we have people doing their own thing it will be far more expensive and take far longer to return to an EI free
status.


Further to this, Dr Bruce Christie, NSW's Chief Veterinarian, has highlighted the dangers of starting a vaccination program now.
 

Vaccination against equine influenza (EI) may well be ineffective and cause more problems than it solves, NSW's chief veterinarian Dr Bruce Christie says.

Dr Christie says containment remains the best weapon to combat the current crisis in NSW and Queensland which has crippled the racing industry and now threatens this year's breeding season.

The first case of EI in Australia was detected in a stallion housed at Sydney's Eastern Creek quarantine station and has now been confirmed in seven stallions there.

All had travelled from the northern hemisphere and all were inoculated against EI.

"You can vaccinate to try to make sure they don't get it but you can see at Eastern Creek they have been vaccinated and they have it," Dr Christie said.

"They would have been vaccinated for whatever strain they have in their country but the strains are just like humans, they change all the time.

"You then have to vaccinate two or three times a year.

"Horses may be vaccinated and not show signs of EI.

"Once you start vaccinating you hide the disease."

NSW Primary Industries minister Ian Macdonald said vaccination would be one of the things looked at but it was an expensive and complicated process.

"There was a meeting of participants today and they were unanimous we must investigate vaccination," Mr Macdonald said.

"But our protocol is based on eradication and we have not identified the full strain.

"The efficacy of vaccination is under question unless you get the strain right."

Dr Christie emphasised the need for vigilance on the part of horse owners and said the containment measures were working and would continue to work as long as the rules were obeyed.

"There is a total lockdown in the state and that appears to be working," he said.

"So far the disease has been linked to dangerous contact properties with horses which went to Centennial Park and Maitland.

"In the majority of cases it has been carried by a person or a piece of machinery or equipment.

"The concern now is people with horses on two acre, three acre or four-acre blocks.

"They must protect the borders and keep the horses away from those in neighbouring paddocks."