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View Full Version : Myxomatosis - Mutated?



sidereus7
25-10-2009, 07:24 AM
I was thinking about all the buns that are getting myxi who were vaccinated lately. I know there has been a lot of speculation about the vaccine not being as effective or the vaccine not being administered properly. But is there a possibility that the virus itself has mutated?

I was reading this website and it had a few interesting points:


The number and severity of outbreaks varies over time: the myxomatosis virus is notorious for its ability to mutate from year to year and the background immunity in the wild rabbit population also varies. For example, in autumn 2000, southern areas of the UK (the south west, Hampshire, Suffolk, Cambridgeshire) experienced a severe outbreak of myxomatosis, thought to have been caused by a particularly virulent strain of the myxomatosis virus.

It also went on to talk about how when you vaccinate your rabbit against myxi, they're not actually getting protected against myxi specifically:


The myxomatosis vaccine in Britain (Nobi-vac Myxo) is made from a harmless virus called Shope Fibroma. Antibodies made in response to Shope Fibroma Virus also protect against myxomatosis - this is called cross immunity. Different vaccines (including live attenuated myxomatosis virus) are used elsewhere in Europe, but tend to have more side effects and there are concerns that they are not safe enough for use in pet rabbits.

It did say some vaccines are actually live attenuated myxomatosis virus, but it says it's too dangerous.

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I guess I'm just trying to throw some ideas out there. I really hope that no more bunnies on here get myxi. :cry:

ETA: Forgot to add my source: http://www.rabbitwelfare.co.uk/resources/content/info-sheets/understanding_myxo_feb06.htm

Jack's-Jane
25-10-2009, 07:32 AM
Viruses mutate all the time :cry: As the vaccine relies on cross immunity from the Shope Fibroma Virus aswell as each individual Bun's immune response there is bound to become a time when the vaccine is less effective. Combine that with the climatic changes we have seen (warm wet Summer/Autumn) and the environmental challenges it brings (increased mozzie population) then what is apparently happening now is not really a complete surprise :cry:

The data I have read about the use of a Live Myxo Vaccine actually stated that it prooved to be LESS EFFECTIVE than using the Shope Fibroma Virus :cry:

sidereus7
25-10-2009, 08:01 AM
The data I have read about the use of a Live Myxo Vaccine actually stated that it proved to be LESS EFFECTIVE than using the Shope Fibroma Virus :cry:

Really? Did they state a reason for it being less effective?

Also, did you own many rabbits in 2000? Did you see any sort of difference in outbreak severity?

Jack's-Jane
25-10-2009, 08:04 AM
Really? Did they state a reason for it being less effective?

Also, did you own many rabbits in 2000? Did you see any sort of difference in outbreak severity?

I will try to find the data I read re the use of a live vaccine.

Yes, I had Rabbits in 2000. What's more they were NOT vaccinated.............

My then Vet said it was 'unnecessary for Pet Rabbits'..............

She also told me VHD was 'extremely hard to transmit'.............

Anyone wonder why I changed Vets once I learned the truth :roll:

I have noticed a significant increase in cases of VACCINATED Rabbits still contracting Myxi in the last 2 years.

*Spider*
25-10-2009, 09:03 AM
This is really worrying.... :(

*lily*
25-10-2009, 09:09 AM
Yes, very worrying as I really thought previously that having the rabbits vaccinated would fully protect them against the disease.

thumps_
25-10-2009, 09:55 AM
I read somewhere that a "calci" virus was introduced in the 1990's "because wild rabbits were becoming immune to the myxoma virus". Has anyone else heard of this or do they have further information?

Jack's-Jane
25-10-2009, 10:05 AM
I read somewhere that a "calci" virus was introduced in the 1990's "because wild rabbits were becoming immune to the myxoma virus". Has anyone else heard of this or do they have further information?

VHD is a calci virus but AFAIK there has been no EVIDENCE of its DELIBERATE release

Santa
25-10-2009, 10:54 AM
To be honest I'm not convinced by the argument that the virus is mutating at such a rate that the vaccine is no longer working. The myxo vaccine isn't made from it anyway so unless it significantly mutates I don't think it will make a huge amount of difference - and if that was the case we would be seeing significant increases in full-blown myxo as if buns hadn't been vaccinated at all. The flu virus vaccine has to be changed annually because the virus is so sensitive to mutations; the fact that the myxo vaccine has worked *reasonably* well for years indicates to me that this isn't the root of the problem. I think it's likely that this is happening to some extent but I'm not convinced that it's the whole story.

I think it's far more likely that the problems over the past couple of years have been caused by the change in seasonal patterns - the past 2 years in particular have seen prolonged wet periods, very heavy downpours and mild autumns - all conducive to the breeding of biting insects. More insects=more transmission=more likelihood of bunnies becoming exposed to a higher dose of myxo.

Don't forget also that this is a very active community here on RU - these sorts of things could well have been going on for years but without us all knowing about each other's cases. I think it's also more likely now that vets will approach severe nodular myxo with an expectation to treat rather than PTS, so we are seeing more of these cases than previously.

areia
25-10-2009, 11:16 AM
what i found out last night some companies are still putting down to kill wild rabbits, i didnt think this was still legal in this country as a form of culling ???,

im not going to name but i reckon its not helping either :censored:


my vet did say theres has been alot of myxi cases this year more in the villages areas than the towns, i agree also with the weather theory too it does make sense

Jack's-Jane
25-10-2009, 12:58 PM
To be honest I'm not convinced by the argument that the virus is mutating at such a rate that the vaccine is no longer working. The myxo vaccine isn't made from it anyway so unless it significantly mutates I don't think it will make a huge amount of difference - and if that was the case we would be seeing significant increases in full-blown myxo as if buns hadn't been vaccinated at all. The flu virus vaccine has to be changed annually because the virus is so sensitive to mutations; the fact that the myxo vaccine has worked *reasonably* well for years indicates to me that this isn't the root of the problem. I think it's likely that this is happening to some extent but I'm not convinced that it's the whole story.

I think it's far more likely that the problems over the past couple of years have been caused by the change in seasonal patterns - the past 2 years in particular have seen prolonged wet periods, very heavy downpours and mild autumns - all conducive to the breeding of biting insects. More insects=more transmission=more likelihood of bunnies becoming exposed to a higher dose of myxo.

Don't forget also that this is a very active community here on RU - these sorts of things could well have been going on for years but without us all knowing about each other's cases. I think it's also more likely now that vets will approach severe nodular myxo with an expectation to treat rather than PTS, so we are seeing more of these cases than previously.

Do you not think that if the virus mutates, which AFAIK it does/will, that the immune response induced by the vaccine (ie the immune response to the Shope Fibroma Virus) may no longer enough to give some protection against the (mutated) Myxi Virus :? Sort of like a mutated Myxi Virus finds a 'pathway' past the immune cells produced by the vaccine.

I may be talking out of me bum, I only got an O Level in Biology !!

nursecroft
25-10-2009, 01:28 PM
Steves dad walks on a farm and he says there are hardly any buns about at the moment, he says he's never seen a year like it for myxi or so few wild buns around. :?

sdf76
25-10-2009, 01:54 PM
Certainly here in Gloucester we have had rubbish summers the last three years -the previous two with extensive flooding and a noticable increase in mozzies and other insects both indoors and out.

Wet warm weather helps mozzies breed and the more of them that there are, the more of them are likely to carry the myxi . The vaccines are never 100% guaranteed (-like all other vaccines), despite having a rabbit savvy vet who injects correctly and 6 monthly vaccines- if there are greater numbers of mozzies and other myxi bearing insects around there will be a greater chance of rabbits catching myxi. Also different rabbits have different immune systems so some fare better than others.

The important thing is that although it is extremely unpleasant for them, the majority of vaccinated rabbits do survive myxi as it presents as nodular myxi which has a much better prognosis if treated quickly.-sue:wave:

edit for grammatical corrections

rabshan
25-10-2009, 04:34 PM
An interesting thought and one i have often wondered about:?around millenium year there was a rumour going around (i had bunnies then :)lots of them and all un vaccinated:shock:) that a new myxi virus had been deliberately brought in from France:evil:it was said that it went straight to the lungs causing Pneumonia and death:cry:many breeders blamed the show people for bringing in imported "stock":evil:this was certainly done with French lops as i had one here that had won a 1st. at the London show:)he was imported from France too:cry:
it was also claimed that farmers had brought this "new" Myxi in as so many wild rabbits were managing to survive the "original" virus so they introduced a new strain which killed many wildies:cry:
As said this was a rumour which spread about quickly:shock:not sure if there is any truth in this but when you examine the facts that so many buns are getting myxi :cry:it does make sense:cry:

Santa
25-10-2009, 05:59 PM
Do you not think that if the virus mutates, which AFAIK it does/will, that the immune response induced by the vaccine (ie the immune response to the Shope Fibroma Virus) may no longer enough to give some protection against the (mutated) Myxi Virus :? Sort of like a mutated Myxi Virus finds a 'pathway' past the immune cells produced by the vaccine.


I would be surprised if that was the case - purely because the immune response produced by shope fibroma doesn't "fit" the myxo vaccine perfectly anyway so it shouldn't make too much difference how it mutates as long as it's still the same class of virus with the same mode of operation.

But equally I might be talking out of my bottom too :lol: If only I'd listened harder in my immunology lessons but they're so long ago I can't remember a thing either :lol:

Hugo's There
25-10-2009, 06:59 PM
I agree that I think the change in weather conditions has a lot more to do with the increase.

Also in the last few years more rabbits are being vaccinated so it therefore follows that more vaccinated rabbits will catch it now just because there are more vaccinated rabbits.

I also think that rabbit medicine has come on in leaps and bounds in the past few years so that there is more of an attempt to treat rabbits with myxi where as in the past they were pts and no-one was any the wiser :?

ETA just another thought, more and more people now have access to the internet so there is better communication between rabbit owners. A few years ago we would have had no way of knowing who's rabbit had got what illness :)