Vaccinate or Not

[jolenesdad]

Mareks is always kind of a hot-button topic. I have hatchery birds and non in my flock, and most of my hatchery birds are mareks vaccinated. My non-hatchery birds have zero vaccinations.

@Mixed flock enthusiast has Mareks in her flock and has interesting experiences and knowledge around vaccinating she was sharing with us in a hatch a long last year. Maybe she can chime in with what she knows.

as far as I know, mareks is interesting in that certain birds can be resistant to it. So it’s all over and brought in by wild birds, but some birds get it and others don’t. The point of breeding for resistance for any disease is that you are trying to continually breed until you only have resistant birds. Lots of culling and improving. Without breeding, culling, and improving the lines, there’s probably much more reason to vaccinate. A serious breeder is going to cull a chick with pasty butt because that’s indicative of a chick with some level of weakened immune system. Are you going to cull a chick you ordered for pasty butt?

if I were only going to have hatchery birds, or just hatch some on my own from others without breeding, I would get mareks vaccination on everything.

many people who do both hatchery and hatch, but don’t seriously breed, vaccinate what they can and treat the non vaccinated bird as sort of “canaries in a coal mine”.

I’m not educated enough on the long term facets of breeding, or the ways chicken immune response and resistance works, so I have a really uninformed opinion, but I have often wondered if the “breeding for resistance” is more of a trope born out of necessity, as breeders don’t have the same access to use such large dose vaccines. In other words, if the vaccines were more cost effective and widely available at smaller doses, would more people be using them? Maybe someone can help me with that view and course-correct my thoughts.

 

[ChocolateMouse]

I definitely think that vaccines would be more prevalent and used in back yard enthusiasts if they were cheaper.
The salmonella vaccine for example. After shipping it'd be about $55 to have it shipped to my house. It's 1000 doses. Assuming it has a retention time long enough to last the two weeks for both doses you need to give for it to be effective that's 500 chicks. That's a tidy $0.11 per chick, very reasonable if you have 500 chicks to vaccinate.
But across 20 chicks it's over $2 per chick. But, if I could get even a 100 dose bottle for $10 or $15, their profit margin is huge compared to the 1000 dose bottle (50 chicks for $15, or $0.30/chick) but I don't have some crazy overhead from a ton of wasted vaccine. I can do 20 chicks for $15 and only add $0.75/chick to my costs.

I think if options like this were more available more people would use vaccines, especially for very specific problems. Since I do mostly artisan egg/some meat production and have some immune compromised people in my life salmonella's a real concern for me so I'd use it.

 

[Mixed flock enthusiast]

We’ve only had poultry for about two years, and my knowledge of Marek’s disease virus (MDV) was pretty superficial at the beginning. I knew about Marek’s but thought it was rare in backyard flocks. I did inoculate our first group of barnyard mix chicks that we hatched with the common, acellular HVT (herpesvirus of turkeys) vaccine. We then purchased two separate groups of purebred chicks from a local, well-known breeder who did not vaccinate but “bred for resistance”. We lost only a few chicks from the first breeder group, but most chicks from the second group died before 2 mo old. At the same time, we started losing older juveniles from the first, POL breeder group. Picture is of Lemonhead, 5 month old East Frisian Gull cockerel, our first bird diagnosed with Marek’s. State lab necropsies showed that all dying birds had Marek’s, which weakened their immune system so some died from coccidiosis or other diseases. Current day, more than a year after buying those two sets of breeder chicks, we’ve lost almost all of those breeder birds at various, vulnerable times: chicks, POL, maturing roosters, after fights, after treating mites, etc. We’ve lost none of our original, backyard mix, HVT vaccinated birds. We now only buy chicks that have been Rispens strain MDV vaccinated, or I vaccinate with Rispens as eggs at day 17-18 if we are breeding them. We don’t sell or rehome chickens. We’ve lost none of these vaccinated, broody raised chicks (knock on wood) which are now POL or just past laying age, even as we’ve continued to lose our unvaccinated chickens.


As for the numerous news article mentioned earlier about Marek’s vaccination leading to hotter strains of virus, those all refer to the same study. That study does suggest that our huge, commercial poultry houses have indeed engaged in a biological arms race between MDV and its vaccines. However, what it shows is that, IF chicks contract the most rapidly lethal strain of MDV, termed highly pathogenic or very virulent Marek’s disease virus (vvMDV), then the vaccine protects them long enough that the virus has time to replicate and be shed by those birds, potentially infecting other birds. IF they are not vaccinated, then they all die so fast that the birds don’t have time to shed virus.


Instead of reading the news articles about the study, go to the actual study, which is freely available at: https://www.ncbi.nlm.nih.gov › pmcWeb resultsImperfect Vaccination Can Enhance the Transmission of Highly Virulent Pathogens

Look at Figure 1, which shows three different outcomes of interest, from top to bottom: percent of chicks surviving after MDV inoculation, MDV shedding over time, and cumulative or total amount of virus shedding over the time that the birds are alive. The unvaccinated groups have dashed lines or lighter color shading. From left to right, we have MDV of different virulences, from mildest to hottest. The first, HPRS-B14, is an older, less virulent MDV where “only” 60% of chicks die. The last strains, like Md5, are vvMDV, where all chicks die. If you have a less virulent MDV, then both vaccinated and unvaccinated chicks get infected and spread virus. But, the vaccinated chicks shed LESS virus, because the vaccine kicks up the immune system of vaccinated birds so they fight viral replication. In addition to shedding less virus, the vaccinated chicks are more likely to survive. IF your have a hotter, vvMDV strain, then just the fact that the vaccinated chicks survive means that they are still capable of shedding virus. The unvaccinated chicks are all dead, so no virus shedding is going on there.


My take on this: Considering that there are probably few chicken flocks that are really MDV free, it makes more sense to me to vaccinate and increase the likelihood that our birds live when a hotter virus strain makes its way to us. Backyard flocks aren’t the ones driving this evolutionary arms race, and we aren’t able to escape it either.

 

[getaclue]

I won't vaccinate. When we hear the term vaccine, we all know what a vaccine is, right? It's a small dose of either live, or dead "bugs" to help build some immunity, and protect against a contagion. That's known as a closed vaccine, and required by law for people. The problem with chicken vaccines, are that they are NOT closed vaccines. Being animals, the laws are very different in the requirements, and the ability to call something a vaccine. What they pass off as vaccines for chickens, typically are not.

 

[NHMountainMan]

Here’s some interesting (IMO. I’m weird lol) articles on it.
https://www.pbs.org/newshour/science/tthis-chicken-vaccine-makes-virus-dangerous
https://www.pbs.org/newshour/science/tthis-chicken-vaccine-makes-virus-dangerous

https://www.nationalgeographic.com/...s-enhance-spread-of-deadlier-chicken-viruses/

https://www.sciencemag.org/news/2015/07/could-some-vaccines-make-diseases-more-deadly

Thanks for sharing those links. Really interesting

 

[jolenesdad]

We’ve only had poultry for about two years, and my knowledge of Marek’s disease virus (MDV) was pretty superficial at the beginning. I knew about Marek’s but thought it was rare in backyard flocks. I did inoculate our first group of barnyard mix chicks that we hatched with the common, acellular HVT (herpesvirus of turkeys) vaccine. We then purchased two separate groups of purebred chicks from a local, well-known breeder who did not vaccinate but “bred for resistance”. We lost only a few chicks from the first breeder group, but most chicks from the second group died before 2 mo old. At the same time, we started losing older juveniles from the first, POL breeder group. Picture is of Lemonhead, 5 month old East Frisian Gull cockerel, our first bird diagnosed with Marek’s. State lab necropsies showed that all dying birds had Marek’s, which weakened their immune system so some died from coccidiosis or other diseases. Current day, more than a year after buying those two sets of breeder chicks, we’ve lost almost all of those breeder birds at various, vulnerable times: chicks, POL, maturing roosters, after fights, after treating mites, etc. We’ve lost none of our original, backyard mix, HVT vaccinated birds. We now only buy chicks that have been Rispens strain MDV vaccinated, or I vaccinate with Rispens as eggs at day 17-18 if we are breeding them. We don’t sell or rehome chickens. We’ve lost none of these vaccinated, broody raised chicks (knock on wood) which are now POL or just past laying age, even as we’ve continued to lose our unvaccinated chickens.


As for the numerous news article mentioned earlier about Marek’s vaccination leading to hotter strains of virus, those all refer to the same study. That study does suggest that our huge, commercial poultry houses have indeed engaged in a biological arms race between MDV and its vaccines. However, what it shows is that, IF chicks contract the most rapidly lethal strain of MDV, termed highly pathogenic or very virulent Marek’s disease virus (vvMDV), then the vaccine protects them long enough that the virus has time to replicate and be shed by those birds, potentially infecting other birds. IF they are not vaccinated, then they all die so fast that the birds don’t have time to shed virus.


Instead of reading the news articles about the study, go to the actual study, which is freely available at: https://www.ncbi.nlm.nih.gov › pmcWeb resultsImperfect Vaccination Can Enhance the Transmission of Highly Virulent Pathogens

Look at Figure 1, which shows three different outcomes of interest, from top to bottom: percent of chicks surviving after MDV inoculation, MDV shedding over time, and cumulative or total amount of virus shedding over the time that the birds are alive. The unvaccinated groups have dashed lines or lighter color shading. From left to right, we have MDV of different virulences, from mildest to hottest. The first, HPRS-B14, is an older, less virulent MDV where “only” 60% of chicks die. The last strains, like Md5, are vvMDV, where all chicks die. If you have a less virulent MDV, then both vaccinated and unvaccinated chicks get infected and spread virus. But, the vaccinated chicks shed LESS virus, because the vaccine kicks up the immune system of vaccinated birds so they fight viral replication. In addition to shedding less virus, the vaccinated chicks are more likely to survive. IF your have a hotter, vvMDV strain, then just the fact that the vaccinated chicks survive means that they are still capable of shedding virus. The unvaccinated chicks are all dead, so no virus shedding is going on there.


My take on this: Considering that there are probably few chicken flocks that are really MDV free, it makes more sense to me to vaccinate and increase the likelihood that our birds live when a hotter virus strain makes its way to us. Backyard flocks aren’t the ones driving this evolutionary arms race, and we aren’t able to escape it either.

Thank you! I’m so sorry you all have gone through all of this, but thankful for your information.

 

[NHMountainMan]

Not true. You cannot compare Marek's vaccines to the ones humans get. Most vaccines (for humans and animals) prevent the recipient from ever contracting the disease. The Marek's vaccines (there are several) are different. They do not prevent the disease. They only prevent the worst of the symptoms.

That is why wide spread use of human vaccines has lead to the complete eradication of some diseases, while Marek's vaccines have arguably just led to the development of more potent strains.

Also, get a flu shot!

Agree!

 

[ChocolateMouse]

"Considering that there are probably few chicken flocks that are really MDV free"

??? What makes you think this is the case, out of curiosity? I hatch my own chicks and get ones from hatcheries and certainly none of my birds show any signs of Mareks. I think that if the majority of flocks weren't Mareks free we'd see a lot more people talking about it - it would be a fact of life for all chicken owners, not a matter of if but when, like CCD in bees - but as it is I'm pretty sure Mareks flocks are still a minority.

Unless you have some research to back this statement up?

Personally I'd rather have all my chicks die and shed no disease and know for sure I have a serious, contagious disease in my flock than to vaccinate and maybe something dies from complications and I have no idea I'm spreading diseased birds around. If Mareks ever hits my flock I want to know for sure with no shadow of a doubt so I don't keep raising/distributing sick chickens.

Good biosecurity should always be the first step to protecting birds also. So I maintain my flock with that in mind. It's better to prevent infection in the first place.

Rest assured, if the Mareks vaccine were sterile or even 50% sterile I would use it every day. But I'd rather have dead chickens than sick chickens. I cull sick birds. I know that's not always popular, especially in pet flocks.

 

[Nay]

Thank you all for the informative discussion in this thread. As someone who is at a similar stage as @KDOGG331 was in the quote below, I've found your posts incredibly helpful. Thanks all

So I guess long story short I was a bit of a newbie and didn’t really know better and thought “vaccinate? Sure! Why not?” And/or thought you had to. I mean, they wouldn’t offer it if it wasn’t a good idea right? Or so I thought at the time.

The Marek's vaccines (there are several) are different. They do not prevent the disease. They only prevent the worst of the symptoms.

My take on this: Considering that there are probably few chicken flocks that are really MDV free, it makes more sense to me to vaccinate and increase the likelihood that our birds live when a hotter virus strain makes its way to us.

 

[NHMountainMan]

I chose to vaccinate my hatchery chicks because that's what we do - kids, dogs, flu shots Yada Yada. Didn't really think about it.
Then I did some reading and saw some of the same articles posted earlier in the thread and the source study. It's hard to know what's the best thing to do for our backyard flocks.
After reading @mixed flock enthusiasts post, I think I'll keep with the vaccinations. To me, survival rate matters.
For what it's worth, somewhere in all of that reading I saw that vaccinated or not, once Marek's hits, it sheds. Not just to your other birds, but coop, bedding etc. And is virtually impossible to eradicate.
Can anyone confirm that? Because if true- the only thing that matters is survival rate.