So I looked into this while sitting in the sun in the chicken yard.
I should caveat this by saying we are right at the edge of my ability to understand the science and the statistics involved.
The original article that was reported on in the pbs article - the one that got everyone in a stew - simply asserted that Marek’s had become more virulent since vaccination began without citing any evidence.
But I dug up an NIH paper where they did phylogenetic modeling.
They basically look at mutations in the virus and built a mathematical model to work backwards in time for when those happened.
Clever stuff - I might need a nap to recover!
They were looking at intensive farming and vaccination timelines - so basically ran their model back to the 1950s.
Although, like the other paper, their paper started with the assertion that the disease had got more virulent, they did cite numerous sources for that observation.
Basically what has happened over the last 50 years is the emergence of some strains of Marek’s that kill unvaccinated birds extremely fast and at a young age. This is in contrast to the more classical Marek’s, that I am sure we have all read about, where tumors develop in slightly older birds causing paralysis and other issues including tumors in the lymphatic system, reduced immunity etc.
I couldn’t get a handle on this exactly but it seems this more virulent disease is particularly marked in broiler intense farming operations.
The conclusion of these phylogenetic modeling wonks was that the use of vaccines has impacted the evolution of the virus such that these more virulent strains have emerged.
There is no discussion about how widespread the more virulent strains are, but a lot of discussion in the references is about broiler operations.
The authors do point out that their work is a model and it is looking at only the last 50 years of what could be a thousand year history of co-evolution of chicken and Marek’s virus, and that the genetic complexity of the Marek’s virus made it impossible to actually match specific mutations with virulence.
So they conclude that their work is supportive of the view that vaccine use has, over a 50 year timeframe, impacted the evolution of the virus towards more virulent strains, but is not conclusive proof that it is the case.

Here is the NIH article if anyone wants to dive in: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5680632/

And for geeky Marek’s posting here is my tax payment. Eli preening at my feet while i trawled through all that.

View attachment 3435777
Nice to see Eli out and about with you.
 
Can I catch insanity from PoonyPoor, possibly? :old :idunno
Heeeeey!

Only avian insanity - and only if you visit her through BeakBook, which actively seems to transmit all sorts of avian afflictions, including Royal delusions!! :lau :lau :lau :lau

Infectious avian assumption tax:
(or should that be 'consumption tax":gig)View attachment 3435865View attachment 3435867View attachment 3435870
The chooks happily demolishing the needles on a few of the small branches I cut for them from the huge fallen limb.
Heeeeey!

(Meanwhile I have yet to try pine trees with my kiddos)

I didn't know they ate pine needles either. I use dried ones as bedding (when I have the energy to haul the cart over to the white pine trees!). I haven't noticed them eating any of the bedding ones.
I haven't noticed my kiddos eating pine needles either.
 
Caturday Saturday

Missy is ready for Spring and so am I!
484E49E2-94BE-4007-8889-EC1F462FF2C3.jpeg

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Nope, different herpes virus, there are actually many many of them. Look at it this way, there are thousands of bird species, they are all birds but not all are chickens.

The only thing you are catching from them is sore ankles from the too of yours 🤗.
Why PoonyPoor, what ever do you mean, there are other birds than chickens? Other birds don’t count.
 
Nope, different herpes virus, there are actually many many of them. Look at it this way, there are thousands of bird species, they are all birds but not all are chickens.

The only thing you are catching from them is sore ankles from the too of yours 🤗.
Coco pecks the back of my legs too!
Xzit draws blood.
Shenandoah poops on my shoes
 

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