rabbits becoming immune to myxomatosis

[SMOGGY 34]

Theres alway been different strains of mixy, and as labsandlurchers said some kill quickly,some take longer, rabbits are certinly recovering from some types of strain where they didn't before.

 

But the rabbit is the great survior, and the one thing we've noticed as soon as mixy makes an appearance round us the rabbits stop using the burrows, making it hard for mixy to spread.

 

Although we have mixy come round at least twice a year it never takes more than 20-30%, still leaving more than plenty behind

 

regards smoggy

[border lad 1,047]

I remember, when mixy, broke out in 1953 on wards, and it ravaged the rabbit population, they were just sitting hunched up, eyes closed an swollen,not able to see, you could not give a rabbit away then never mind sell it for 2shillings =10p, but without a doubt rabbits have built up a resistance against this disease, now there is more rabbits up here, ( around were I live,) than there ever was, this year I have come across a couple in the beginning of september, which is not bad considering the rabbit population,

[8shot 192]

I remember, when mixy, broke out in 1953 on wards, and it ravaged the rabbit population, they were just sitting hunched up, eyes closed an swollen,not able to see, you could not give a rabbit away then never mind sell it for 2shillings =10p, but without a doubt rabbits have built up a resistance against this disease, now there is more rabbits up here, ( around were I live,) than there ever was, this year I have come across a couple in the beginning of september, which is not bad considering the rabbit population,

 

 

i found one hunched up while out ferreting flies were all over it

it didnt see or hear me comming

 

so i did the right thing i let the dog deal with it

 

atb

[droid 11]

It's the usual thing with viral diseases that when they first emerge (or are introduced ) they have a very high mortality. The target population contains a range of natural immuniity to the virus, and immune individuals survive to breed, so background immunity increases. Just think of the previously devastating diseases that are now childhood irritations, like measles...... Or indeed flu.

 

If myxi mutates though, it's back to square one. Looks like this is the case to a certain extent.

 

The same thing is going on in commercial fisheries with KHV.

[lurch46 2]

WELL I HAVNT SEEN AS MANY THIS YEAR HAS LAST FEW YEARS

[billy_wizz 2]

I'm no expert but I think the biggest worry is if mixy mutates to heavily leaving any resistance gained almost useless!

[cookie 2 8]

we had it round here bad it was allright for him to practice on but now when you go out theres not many rabbits i think i'll have to walk further .It's s**t when you lamp a feild and there;s nowt there

[comanche 3,109]

The Myxomatosis virus -like any other -is constantly evolving to ensure its own survival . A disease that wipes out all its hosts will itself die out .

 

So when the first wave of myxy came close to wiping out the rabbit population in the 1954 it was almost too virulent for its own good. Subsequent waves of the disease had less effect as a few rabbits started to recover and probably carry immunity for the rest of their short lives and possibly the milder strains of the disease took hold as the fatal strains "killed themselves out".

 

I'm not convinced about immunity being passed to the young rabbits . Certainly not a long-term immunity . Even the vetinary innoculation against myxy is a bit hit and miss and at best only offers protection for 6-9 months.

 

As has been mentioned the disease can be likened to measles in humans in that an adult that has survived the disease will be unlikely to catch it again due to the body having developed the correct immunities but this immunity is not passed to the children . When I was young it was common for us children to be sent round to see our sick friends so that we would deliberatly catch mumps ,measles or whatever was going round at a young age so that we'd be immune for the rest of our lives .

 

I think it is more a case of the parent rabbits having either escaped the disease or recovered from it managing to live long-enought to breed at a time of the year when myxy is less common . Also the rabbit fleas that carry the virus need to eat blood from pregnant adult does for themselves to reproduce and are not that interested in living on baby rabbits .

 

So it stands to reason that in spring and early summer when rabbits are building-up their population the fleas are doing the same . Hence ,come autumn the rabbit population is at its highest and becoming stressed which coincides with the myxy carrying flea population being at its most virile . This is why most big out - breaks occur at this time of year .

You have to remember that both the disease and the rabbit are foreigners in a strange land to some extent and whilst both seem to thrive a little too well at times they hav'nt developed any real sort of natural balence and possibly never will.

Edited November 1, 2009 by comanche

[droid 11]

The point I was making was not neccessarily that immunity to Measles was passed on to offspring but that the disease itself had less effect on a population that had been exposed to it for many generations. It's still a serious (read fatal) disease to populations that have never seen it. I think it is this you notice rather than the more lethal strains of virus 'killing themselves out'.

However, in placental mammals you do get short term immunity passed on from mother to offpring, since the antibodies can pass the placental barrier.

 

I can't see fleas passing up a blood meal whether it's from an adult or a youngster.

 

Myxi isn't wiping out the rabbit population in this country, so the 'natural balance' you speak of already exists. Like in predator/prey relationships, a true equilibrium is rarely found.

Edited November 1, 2009 by droid

[RicW 67]

The point I was making was not neccessarily that immunity to Measles was passed on to offspring but that the disease itself had less effect on a population that had been exposed to it for many generations. It's still a serious (read fatal) disease to populations that have never seen it. I think it is this you notice rather than the more lethal strains of virus 'killing themselves out'.

However, in placental mammals you do get short term immunity passed on from mother to offpring, since the antibodies can pass the placental barrier.

 

I can't see fleas passing up a blood meal whether it's from an adult or a youngster.

 

Myxi isn't wiping out the rabbit population in this country, so the 'natural balance' you speak of already exists. Like in predator/prey relationships, a true equilibrium is rarely found.

 

Ho hum. You are all wrong. All this nonsense about evolution. When Rabbitgod first created the world He made the Vegetable Garden of Eden. He placed Rabbitadam and Rabbiteve in the garden. He told them that were free to enjoy the fruits of the garden. BUT they must never nibble on the leaves of the cabbage of the knowledge of good and evil or taste of the leaves of the cauliflower of the knowledge of life.

 

Yet Unbeknowst even to Rabbitgod, there was a worm in the garden. And Lo one day the worm snuck up to Rabbiteve and said "Tell yer what sweetheart try a bit of this." And Rabbiteve was tempted and fell. She and Rabbitadam were naked,yet having tasted of the leaf of the cabbage of knowledge of good and evil she persuaded Rabbitadam that he must grow a fur coat to hide his nakedness.

 

And this Rabbitgod saw and waxed mighty wrath. He said unto Rabbitadam and Rabbiteve "right you pair yer barred. Out - now."

 

And Rabbitadam and Rabbiteve and were slung out the back.

 

But Rabbitgod was not yet finished. He said unto them "If ever again ye transgress I will curse ye with the dreaded blight of the Myxy" . And always since that dreaded day if ever a rabbit should dare to spread its seed around the world it will be struck down by the curse of the Myxy.

 

Nothing to do with the fact that myxy was developed at Porton Down.

 

Ric

[Cold Ethyl 63]

The problem is myxi mutates as well as fast as the bunnies build some sort of defence it almost wiped the population of bunnies here completley.The pet bunny jab is a waste of air as far as i can see ive kept them as pets and the jab did f all for those who ive seen use it mine never had a jab in their life and none died of myxi?I would love to think the rabbits could get an immunity to it and for myxi to be erradicated but its doubtful

[comanche 3,109]

The point I was making was not neccessarily that immunity to Measles was passed on to offspring but that the disease itself had less effect on a population that had been exposed to it for many generations. It's still a serious (read fatal) disease to populations that have never seen it. I think it is this you notice rather than the more lethal strains of virus 'killing themselves out'.

However, in placental mammals you do get short term immunity passed on from mother to offpring, since the antibodies can pass the placental barrier.

 

I can't see fleas passing up a blood meal whether it's from an adult or a youngster.

 

Myxi isn't wiping out the rabbit population in this country, so the 'natural balance' you speak of already exists. Like in predator/prey relationships, a true equilibrium is rarely found.

You might not think it Droid but I was'nt disagreeing with you on your main points but I probably did'nt put myself over very clearly .

You are right when you say populations ,be they human or animal ,often react badly to initial exposure to a novel disease and that a degree of aquired immunity is soon developed . This new immunity is often only valid if other living conditions remain at as high level. In conditions of stress ,such as is caused by overcrowding ,low nutrition ,poor housing or simply mental and physical "depression" these immunities may not be strong enough to fend off infection .

Witness Farley Mowatt's description of Canadian natives who despite 150 years of exposure to European disease continued to die . Their bodies weakened by poor diet ,living conditions and lack of cultural understanding could not develop strong anti-bodies . Official cause of death -Tuberculosis, real cause -starvation and stress.

 

I know that myxy is ticking over all the year round in many places but most major outbreaks occur at the begining of autumn -the rabbit population is high ,the grass is getting damp (which triggers enteritus ,another common usually sub lethal disease of rabbits ),the burrows are overcrowded ,there is a chill in the air and myxy strikes .

As to the theory of a disease "killing-itself out". In early experiments strains of myxomatosis were isolated .

The strong strains had 100% kill-rate which clearly limited its ability to spread. The slightly weaker strains of the disease left a little nucleus of survivors which in turn ensured the survival of the infected fleas they carried .

Droid makes valid points when he says that as myxy is'nt wiping out the rabbit population in this country so a balence must be forming and that true equillibrium in nature is rare . The so called "Balence of Nature " is more like a see-saw!.

I do think the balence is still in a rather early state of development though . The myxoma virus is endemic to one species of South American rabbit. It is carried in the natural state by flying insects and is ,"a comparativley benign or seldom fatal disease in the Brazilian rabbit"( Lockley)

The rabbit is an alien species to Britain,Myxomatosis is an alien disease both to Britain and the European rabbit and the rabbit flea is not the natural vector of the disease.

Is it any wonder that the struggle to form a slightly less dramatic relationship between these factors is very much ongoing ?.

Actually I suspect Ricw is really right .

Edited November 2, 2009 by comanche

[droid 11]

Point taken, Comanche. The beauty (and often frustration) of Biology is that it's a science of interpretation as much as anything.

I think your analysis of myxi being latent in rabbit populations, only being problematic in times of stress is valid. There's a similar situation with fish disease. And I agree that the 'see-saw' effect is rather dramatic at this stage in myxi's development. If the virus mutates regularly the see-saw might never truly balance.

[RicW 67]

.

Witness Farley Mowatt's description of Canadian natives who despite 150 years of exposure to European disease continued to die . Their bodies weakened by poor diet ,living conditions and lack of cultural understanding could not develop strong anti-bodies . Official cause of death -Tuberculosis, real cause -starvation and stress.

 

 

Official cause of death - Tuberculosis, real cause - unrestricted free-market capitalism.

 

RicW

[J Darcy 5,871]

The rabbit is here forever.....Thank god!