Necropsy prelim. results

I don't mean that in any way having vaccinated birds with unvaccinated birds will be as effective as the vaccine itself BUT my state vet told me via telephone that unvaccinated birds (and vaccinated birds) CAN in fact catch multiple forms of the virus INCLUDING the vaccine form from the vaccinated birds. The vaccine is the LIVE turkey herpes virus! I am not questioning your experience pips and peeps, I am just repeating what I was told by an expert. My opinion on the matter though was that this can only help the unvaccinated birds since, like the cowpox virus, the Marek's virus is similar enough to the turkey herpes virus for the immune system to recognize it as foreign and bad and build the same sort of immunity that the vaccine provides.

pips&peeps :

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This is not true.​
 
Hi Jadeybaby. I'm sorry you have gone thru the same thing. It's just heartbreaking. I see you've done alot of reading (maybe you're OCD like me, LOL).
The best info I've found is in a book called "Poultry Diseases" edited by Saik. It's a reference book for vet school.
There's alot of info out there, most of it is simple, general information, then there's erroneous information, or outdated information. Some info from vets may also not be completely correct. Sometimes I think that we chicken owners may have the best info because of our backyard forum.

From what I've read so far, the vaccine prevents 90% of vaccinated chickens from dying from tumors and paralysis, but does not prevent the vaccinated chicken from carrying and shedding the virus to others- IF exposed to Marek's.

As far as unvaccinated chickens gaining some immunity from the vaccinated chicken vaccine, I'll have to look that up, I don't think I've read that before.
 
I too have been told unvaccinated chicks can catch the virus from vaccinated birds but it's the same rarity as a bird catching the disease from being vaccinated itself. I personally would not use it as a way to gain immunity for an unvaccinated bird as it's such a crap shoot. The other scary thing is the virus is no longer a form of the turkey virus. They had used that for many many years but of course, the virus mutated and became more virulent. Now they use a combination of at least two different strains of the virus in the latest vaccines.

Why some birds get it and some don't...the same reason some people get the fashionable flu of the season and others don't. Some people have a stronger immune system or their system has encountered the germ before and has an immunity to it. Same could be said of birds...stronger or "been there, done that" immunity. If Mareks is "everywhere" it's not hard to imagine our beloved, brooder raised babies have come in contact with the virus in small enough amounts OR if they are vaccinated, they have a immunity.

Birds that succumb to it are, perhaps, more easily stressed which lowers their immunity or they personally went through something that lowered their immunity. As our vet put it, herpes is an opportunistic virus so it's always knocking at the door just looking for a chance when the immune system is preoccupied.

Here is the problem I have with the vaccine: Its said you MUST vaccinate chicks within 24 hours of hatching -- fine. WHY are vets recommending people with outbreaks vaccinate their older birds as a precaution? How is that logical? Our vet said...if they are older than 24 hours, don't even bother, go for age developed immunity. I know vets all over have different takes on this disease (frustratingly) but can someone explain to me what was told to them about vaccinating their older birds when it goes against what is said about giving it to chicks?

(Another bachelor pad family here.
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Hi Miss Reikistar (proud bachelor pad owner, LOL)

As far as I know, unvaccinated chicks CAN catch the virus from vaccinated chicks. If those vaccinated chicks have been exposed to the virus, before or after vaccine. Example; my flock carries it. New chicks will be vaccinated. However, those vaccinated chicks will most likely carry the virus that the flock has, and can shed it. But 90% of those vaccinated chicks will not die from it.

My silkies were exposed 2 years ago and 1 died. The rest produced and hatched their own offspring, and they have not died from it, most likely some maternal resistance. However they will still be carriers and shedders.

You must vaccinate chicks prior to exposure to Marek's, the vaccine only prevents tumors and inflamed nerves. Vaccinating older birds ONLY works if the adults have NEVER been exposed to Marek's. But is vaccinating adults any better than age-aquired resistance? And chances are adult birds have most likely been exposed already, and it will be their age aquired resistance that saves them-not the vaccine. Vaccinating older adults would be like the vaccine acting as a booster shot. But if the vaccine can be used as a booster shot, why are we not giving it periodically rather than just once in chicks? I'm thinking it's because the vaccine does not protect against the virus, just the tumors and paralysis.

I think alot of this Marek's stuff is confusing to vets as well as us. We all think that a vaccine prevents a virus, period. It's hard for us to understand the concept of a vaccinated bird still carrying the virus, although not dying from it.

Chicken farms vaccinate, grow out, remove chickens, disinfect, get chicks, vaccinate...etc. The vaccine works for them and most vets and farmers do not need to know any more than that. But we with the small backyard flocks being added to or subtracted from, is a whole newer concept, esp when our chickens are going to live longer than 12-20 weeks (life of a broiler). In 4 years, I've seen BYC go from 8,000 members to 100,000 members , and that's just members. I don't think research has kept up with the increase in the # of small flock owners, and the more complex problems.

Okay, off my pedestal!
 
Well, like I said previously, Marek's is a herpes virus. We all know that once you catch it, it is always there. Marek's lays latent in the cells and waits for an opportunity to take over. Some people also catch the flu after being vaccinated because the virus is constantly mutating and changing. The viruses in the vax for each season are a guess as to which strains they think are going to be the worst for the season. Not to mention, in the human population, vaccines are only effective in 70% of the population. Yeah, it's true. I didn't just say the things that I said because I heard them from an unreliable source like a local pet vet (no insult intended). The info I got was from my state vet, the one who was supervising the necropsy on two of my chickens who had been sent in to UC Davis (a very high ranking vet school). Since the virus in the vaccine is attenuated or "weakened" it does reproduce although slowly, it can be spread to other birds in contact. I am not saying that the birds in contact with the vaccinated birds will get sick. I would guess that if they do contract it, it would only help build their immunity just as the introduction into the vaccinated birds helps build their own immunity. My thought about the unvaccinated birds getting an immunity boost from the virus contracted from the vaccinated birds was an educated guess. I am continuing my education in microbiology and when you know how the human immune system works and how viruses work, it seems logical. When we come in contact with the virus in question or one in the same family (keep in mind, viruses are very simple organisms consisting of DNA or RNA and a protein coat so when our system recognizes it by cell surface markers, it will usually recognize many different kinds of that virus in the same family) our memory cells kick in to fight it and build even more immunity to it.

The smallpox vaccine was discovered because milk maids seemed to have immunity to smallpox. In 1796, a scientist named Edward Jenner inoculated a small boy (very immoral and illegal by today's standards) with the cowpox virus and later with the smallpox virus to see if in fact, the introduction of cowpox "taught" the immune system to recognize smallpox as as a threat as well. We later learned that this was because the two viruses are very genetically similar even though cowpox only causes small blisters and smallpox causes death.

When humans are infected with a herpes virus, it lays latent (hides) in the cells of the nervous system. Our immune system cannot expel the virus and so it is basically held at bay. When our immune system becomes compromised for some reason (a nasty cold or the flu), it shows itself and we see the signs (cold sores), sometimes even before we see the symptoms of the illness that is suppressing our immune system.

I just checked the vaccine I have in my fridge, it's Fort Dodge serotype 3 live virus and does contain the live Marek's virus in addition to cells infected with the live turkey herpes virus. I've used this for all my day old chicks and so far, so good. Remember, my original flock are carriers of a very virulent strain of Marek's. It is also possible the little ones have gained some immunity from indirect contact to them as youngsters though. While my chicks were young, I tried my best to practice an aseptic technique when caring for both the infected flock and the young ones but since feather dander is carried on the wind and I don't have acres and acres, (I'm in CA...North CA no less) but in fact a small city lot, it was just impossible. My broody hatch had constant contact with their "mom" and the rest of the flock the whole while and are now 6mo olds. All seem to be doing well and I am keeping my fingers crossed. If they make it to 2 years, I believe they will be just fine.
 
Jadeybaby, you have certainly done alot of reading. I understand "virus" but never fully understood "herpes virus", and I think you've made sense of it for me here.

I've noticed, too, that my own chickens own hatches by brooding, that the chicks were resistant, and went on to hatch their own chicks, etc. But when I bought eggs and let my chickens hatch them, 7 out of 10 died of Marek's.

Do the vaccinated chicks actually "get" the virus to carry and shed-from the vaccine, or does the vaccine just protect them when they pick up the virus , meaning they won't develop the tumors, but can carry and shed the virus ? I've read that the vaccine can not give them the virus.

Do you where I can find the info or ingredients of this Marek's vaccine?
 
Hi Karen,
I got my info actually from an MSDS report for the specific Fort Dodge vaccine. Here's the address https://www.pfizeranimalhealth.com.au/documents/e/1379/6147,Poulvac HVT CF Vaccine.pdf
after looking at it again, I believe that I was originally right in saying that it was purely the turkey herpes virus. BUT this MSDS report is from 2007, so let me see if I can find anything more recent.

Chickens can become infected with may forms or variants of the virus and they carry and shed them all. Like you said, the vax only prevents nerve inflamation and tumors but does not prevent infection by the virus nor does it stop the virus from reproducing in the birds. Becoming infected with one or more of the less virulent viruses helps the bird's immune system for when it may eventually come in contact with a more virulent strain. Now, I'm not sure how the virus works in the cells of the bird. It involves an increase of leukocytes and lymphocytes (the immune system soldiers), T cells in particular but I have not been able to find info about the direct histology. I know also that it also effects certain cells such as neurons, muscle cells and the cells of visceral organs (heart and lungs in particular).

I don't have a roo (not a mature one anyway). I have bought hatching eggs and hatched them myself or with a broody. I admit I was careless with the broody hatch because the little ones were exposed directly to the virus the second they were born. I vaccinated them the day they hatched but that doesn't mean that they weren't able to pick up the bad strain first and they would have to build up immunity before being exposed to it. I don't know if they have temporary immunity from their moms like mammals do either. BUT the eggs that I let my broody hatch were Marans eggs and the breed is known to be very disease resistant from what I have read. So, they may just be superior genetically in this case. Who knows
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Like I said, if they make it to 2yrs, I will assume we are home free
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Jadey, those bought eggs may have come from a hen who had some immunity.

I was studying the label of my Marek's vaccine in the fridge, and it says "serotype 3-live virus". I think there are other types as well. But mine seems to be an attenuated virus.

I have 3 out of the 10 left that my silkies hatched. They look okay and they are 17 weeks old. Can I put them out with the flock? I know they are all exposed but I'm worried anyway.
 
Mareks is everywhere. I had the UConn vets here and they told me that they consider Mareks to be all over the place. There is no way to prevent it, and the vaccine works on those it works on in the isolation of the incubator or brooder, before the chick has been exposed. It doesnt work all every chick either, but I assumed that was due to the instability of the vaccine itself.
Mareks is all over the place and wild birds carry it, so unless you run a huge poultry facility, its not as much of an issue as to how you got it or cleaning up...
MG is also everywhere as is staph....you can only practice the best biosecurity you can...
I have turkeys and have lost a few young birds this year to Mareks. These were vaccinated birds...and its hard to tell why.
I think that the vaccine is not 100% effective for every strain.
Most of my birds are vaccinated, I keep turkeys, and I keep a very clean setup here, using the UConn vet extension for anything questionable and testing my birds for anything it makes sense to test for.
Its hard to lose a bird to mareks, but the disease is seemingly not painful because of the paralysis, so its not the worst way to go. Ive never had a bird with it that seemed in pain.
I suggest to everyone in my group that they try to only buy vaccinated birds. Vaccinating broody chicks in the nestbox doesnt do anything, and only introduces the live virus via the vaccine to the flock, in case anyone there is likely to get it.
also silkies and other small weaker birds are more likely to get it.
Most of what I believe about mareks comes from myown first hand experience, and experience in running this group and helping people out. I also have researched and asked the extensions whenever I could.
Vets dont know much. Ive watched even avian vets state things incorrectly and dispense incorrect meds over and over. If anything the poultry specialists may know at the university extension, but then, keep in mind that their knowledge is much more about large poultry operations rather than the backyard chicken keeper.
a big problem that Ive found is that previously, as backyard chicken keeping has grown, hatchery owners have believed that vaccinations were unnecessary for small backyard flocks. I completely disagree... they also dont explain about isolating your day old vaccinated chicks. The average person starting out in chickens would already have made many mistakes before they even cracked a book or looked online.
So, I say vaccinate, and just try to cope with the cases of mareks you get, put the birds down asap, if you can, because they are shedding the disease.
Make use of your state vet if you can, and try to necropsy birds unless you are sure of the diagnosis....but know that this is not a curable disease, and vaccinating adult birds or babies in the barn will not work, and might hurt. good luck!

Melina
 

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