Vaccinate or Not

[Mixed flock enthusiast]

"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.

It’s true that we don’t know the true incidence of MDV in backyard poultry. I do know people who transferred MDV into their backyard flock from feed store chicks, and so am guessing that just walking into and out of a feed store (or livestock show) has the potential to transfer this highly persistent and contagious virus. Since most people don’t maintain a closed flock, plus go to feed stores, swaps, and shows, there is tremendous potential for transfer. Actual surveys of prevalence that I’m familiar with have been of commercial poultry, such as:

https://www.ncbi.nlm.nih.gov › pub...Industry-Wide Surveillance of Marek's Disease Virus on Commercial Poultry Farms.

There is some info about backyard poultry incidence of MDV, with several US state diagnostic labs that serve small flocks stating that this is their most common infectious disease diagnosis:

oces.okstate.edu › delaware › newsWeb resultsMarek's Disease in Backyard Chickens — Delaware County Cooperative Extension
Causes of mortality in backyard chickens in northern California: 2007–2011
Postmortem survey of disease conditions in backyard poultry

 

[ChocolateMouse]

None of that seems like conclusive evidence that most back yard flocks aren't MVD free at all. Just because it's the most common infectious disease diagnosis doesn't mean it exists in most flocks. It's an infectious disease after all and something has to be the most common.

What this does scream to me is that people are woefully uneducated about biosecurity and quarantine procedures. I don't wear the same shoes out that I do into my lawn or chicken pen. I have special yard shoes and change my clothes before I go into my pen after being around other poultry keeper intensive areas like the feed store. If there's actually live chickens there, say like at shows or fairs, I take a shower afterwards too and wash my shoes even though I don't use the same ones to go outside. New chickens are quarantined for a minimum of a month before going outside, longer if they're chicks, and they get cared for last and have their own equipment that doesn't rotate to avoid cross contamination. To some people this sounds like a lot but it's actually really easy common sense procedures. This is the minimum biosecurity I think people should have. I really ought to be doing more.

I'd think that having a vaccinated flock would make it really easy to "hide" if you have Mareks and make it MUCH easier to spread it on your clothes or other objects to other chickens or even sell infected chickens to an otherwise clean flock.

I really hate the idea that my clean flock could be ruined by someone who has no idea that they even have sick birds because their flock came in vaccinated and they thought they were healthy and never thought about it again. Everyone with vaccinated birds should treat their flock as if it's diagnosed with mareks IMO. Including cleaning up before going out to common spaces and not selling, showing or swapping any birds.

Non sterile vaccines are always going to be a hard no for me. They don't prevent anything and put other keepers at risk if I don't have a diagnosis and a strictly closed flock. This way everyone who gets birds from me KNOWS they're clean.

 

[ChocolateMouse]

I suspect that what we can all agree on is we are in desperate need of a sterile vaccine for Mareks or a massively successful anti-viral treatment or resistant breeding program. And then have the heck promoted out of it. And I wish more was being developed for it.

 

[CSAchook]

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.

Thanks for sharing your findings and experiences.

 

[Mixed flock enthusiast]

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.

Infectious Marek’s disease virus persists in feather dander for 3 weeks to 3 years, depending on temperature and humidity.

Survival and Disinfection of Marek's Disease Virus and the Effectiveness of Filters in Preventing Airborne Disseminationa

 

[ChocolateMouse]

Yep. I'd rather take the nuclear option and wait 3 years than have a mareks flock. It would make progress towards getting rid of the disease if everyone did but most people just... Won't. So there it is.

I think it would also be nice if Mareks were on the NPIP. And we had state sponsored testing for it and a program the incentives a Mareks free flock. As it is, every chick is a potential disaster.

 

[FortCluck]

To me a lot of people freak out over things like Marek's and to me it seems almost fear mongering... Hopefully I don't sound like too much of a tool, but I've yet to meet someone locally with it in their flock or experienced it.

If it were that common, wouldn't I know at least 1 person of the 30 farmers/chicken owners I know personally?

 

[ChocolateMouse]

I've also never met anyone locally with it, but sometimes I wonder because if they are the sort to have vaccinated birds... How would I know if they have it? But most people I know with chickens are also unvaccinated so it'd be pretty obvious. Hence my deep skepticism over the statement most flocks have it.

In any case, I've heard enough horror stories to set up biosecurity routines. But I think the biggest problem is that once you have it it can take years to get rid of it and without the vaccine that means no chickens for years. Either that or the chickens are more pets less breeders or food or livelihood and so of course you don't want your pets to die horribly and are worried. Most people don't want to (or can't) scrap their whole flock or see their pets die only to wait years to start again.

 

[Fluffyflufffluff]

Who gets their chicks vaccinated...

Why or why not

Answer poll then comment you opinions below

Conventional poultry are usually vaccinated against a variety of diseases including Marek's disease, Newcastle disease, infectious bronchitis, infectious laryngotracheitis, fowl pox, and fowl cholera. Since these diseases can also infect organic poultry, a routine vaccination program is recommended.

 

[NHMountainMan]

To me a lot of people freak out over things like Marek's and to me it seems almost fear mongering... Hopefully I don't sound like too much of a tool, but I've yet to meet someone locally with it in their flock or experienced it.

If it were that common, wouldn't I know at least 1 person of the 30 farmers/chicken owners I know personally?

I think so few chicken owners send a dead chicken for a necropsy, that the true infection rate is completely unknown. And since many chickens survive it, though still carry it - it's likely a much high rate of incidence than we think. Likewise - the weakened chicken could die from coccidiosis, or other illness, and the underlying infection would never be identified.

regardless - the chicks I'm ordering today will be vaccinated (except the cornishX)