Mareks Disease

[Lisa Weaver]

Hi there

Does everyone vaccinate their chicks against Mareks Disease? I have read so many conflicting things that I don't what to do???

 

[rick]

I've just read the Wikipedia page on Marek's and it's pretty shocking!
You wont get the vaccine in small quantities Lisa and so domestic chickens will never get vaccinated. Any breeders for the domestic market would have to vaccinate at the same scale as commercial flocks so I very much doubt that they do either. Apparently all commercial flocks worldwide are vaccinated (with scary effect if I understood it right) but they will be buying it in bulk and it doesn't keep so the vet can't put some aside for later.
I wouldn't worry about it as there is very little, if anything, that you can do but (again if I understand right - and it does make sense from what I've heard) non-vaccinated birds are very unlikely to get highly virulent strains of the disease so they can recover with care although the flock has to be kept closed from then on as they will be carriers.
https://en.wikipedia.org/wiki/Marek%27s_disease
... It very much highlights the difference between domestic and commercial chicken keeping - We rely on keeping them on good food, in a good environment and with little stress so their immune systems can usually deal with things. Commercial flocks may be fed well (thought with very limited variety) but the environment and stress means that if they weren't vaccinated and anything like this got in it would wipe them all out like a wildfire!
... Sorry to go on, but the implications of this are just sinking in! - If a vaccinated bird gets Mareks (and the vaccine wont stop them getting it) then they will show no symptoms but will/may quickly become carriers of a highly virulent strain. Any non-vaccinated bird with a depressed immune system that they come into contact with would not stand a chance!!! Ouch!

 

[rick]

As a footnote - the vaccine is given most often in the egg. One day old chicks can also be vaccinated. I think breeders often dont shoot themselves in the foot by saying that their stock isn't vaccinated - everyone is saying it so to not say it would look complacent - but none of them are! What does happen is protection against coccidiosis by giving medicated feed which is very sensible. So when asked the question 'have they been vaccinated?' - Oh, yeah - totally!
Honestly, dont worry about it. The only vaccinated hens come from the industry. Some of those eggs may end up in a backyard (lucky hens!) but the rest - all the lovely hybrids and pure breeds - it doesn't happen and it doesn't matter because they are not subject to the same pressures.

 

[Marigold]

I agree with Rick that vaccinating against Mareks is impracticable for small-scale keepers, - but so is vaccination against a whole raft of other chicken diseases which commercial flocks will be protected against. Some of the doses have to be given more than once, and at particular ages. As you’ll know, once Mareks is present in a flock all the birds will be carriers and can infect new stock imported from elsewhere, thus potentially causing flare ups. It’s just a choice you have to make if you want to hatch or breed your own. It’s not inevitable that Mareks will occur in an unvaccinated flock, especially if they are well kept in all other respects so their immune systems are strong. Unvaccinated flocks are just as likely to suffer from other diseases that are difficult or impossible to eradicate without an all-out policy, such as infectious bronchitis for example.
It depends what you want to do with your chickens. If you just want a few healthy birds as pets who also lay well, then vaccinated hybrid POL pullets are a good choice. If you want to buy and hatch unvaccinated purebreds, be very careful about the source of your original eggs or young birds, reduce the chances of infection by keeping to one trusted source if possible, and keep a closed flock thereafter.

 

[Hen-Gen]

Totally agree. The only thing I would add is that if at all possible never buy in new birds for your flock. Buy hatching eggs and rear your own birds.
If you do have to buy in birds then do so Nov-Jan. Introductions at this time are relatively stress free and Mareks, perhaps more than most disease, seems more common when birds are stressed.

 

[MrsBiscuit]

Hardly anybody vaccinates against mareks at home, its not practical with just a few birds.

It didn't use to be widespread, the advice about keeping a closed flock, but I will agree, just based on personal experience, although its not something you are likely to achieve or necessarily want to achieve in the early days of chicken keeping because you are finding your way and what you like or the calibre of bird you have to work with. I have only experienced a very mareks-like disease once (you can only tell definitively if a bird has had mareks via a post mortem and hardly anyone has that done unless there is a compelling reason), and that was from a pair of bought in local 8 week old pullets, only one fell ill and died several weeks/months later and there was no flare up subsequently, so maybe it wasn't mareks, who knows. The surviving sibling went on to be a super layer and Mum. I don't remember quite why I was buying them now, but I have learnt my lesson. My advice is to try to buy from a reputable breeder if you go for non-hybrids. I used to source mine via shows, my local poultry club, and the back of Practical Poultry magazine, where you'd get to know the names, particularly those of experienced breeders.

 

[Marigold]

But be aware that Mareks can be transmitted in the egg, hence many infections show up in chicks.

 

[Hen-Gen]

But be aware that Mareks can be transmitted in the egg, hence many infections show up in chicks.

Yes it’s a very interesting disease both because much new work is being undertaken and also because it can resemble some other diseases. For those with an addiction to learning about this disease then I’d recommend:-
Mareks Disease - An Evolving Problem by Fred Davison and Venugopal Nair. (2004).
It is known that disease transmission is via a healthy hen inhaling infected particle of feather dander or dead epithelial skin cells from an infected bird. It is therefore quite possible that eggs from an infected hen could carry the infection as dust particles on the shell which could then infect the new chick at, or soon after, hatching. It is also important that hatching and rearing is done in a clean environment. A strategy of washing and sanitising bought in hatching eggs would seem a wise precaution. But so far as I have been able to ascertain the infection is not passed on within the egg from mother to hatchlings.
This is a disease which is distressing to encounter. I have only experienced it once years ago amongst a batch of Welsummers. I subsequently read that some breeds are more susceptible than others, notably Welsummers and Silkies. Euthenasia followed by thorough sterilisation would seem the most practical strategy.
Genetic resistance can be quickly developed. By breeding from survivors of an outbreak where losses were 50% then in just three generations resistance was up to 94%. It is also possible, I might say certain, that new techniques such as gene editing will be used to create immunity in commercial strains of chickens.

 

[Marigold]

That’s interesting about the infection originating from virus particles deposited on the shelI by the hen. I had assumed it was within the egg, I.e, via direct transmission from the hens oviduct to the embryo before the shell was developed around the contents. I had also heard that it was important to use naturally clean eggs for hatching as messy eggs could obviously carry infection, and that washing eggs wasn’t a good idea as it removes the protective coating from the shell and allows infections to enter more easily through the pores of the shell.
How do you recommend washing and sanitising eggs, HenGen?

 

[Hen-Gen]

All valid points. All eggs incubated from ones own hens should be clean. Thus they are never washed because any infections in my birds will be passed to the chicks in due course anyway. Soiled ones should be discarded, fed to livestock etc. The shell is a protection against bacterial infection but with bought in eggs you may need to be a bit more suspicious.
So:-
1) Prepare a bowl of hand warm water. Too hot and you damage the egg. Too cold and the egg actually sucks in any bacteria.
2) Add Egg Disinfectant at the prescribed dilution.
3) Hold the egg pointy end down and immerse in the solution. Straight in and out, do not leave in the solution.
4) Dry each egg immediately with tissues. Do not set aside to dry as the cooling water may be sucked into the egg.
Is all this worthwhile? Does it reduce hatch ability? I can’t answer those questions. The risks are low anyway not least because diseased hens stop laying. As with many things in life when buying in eggs, as I do sometimes from eBay, then one has to trust the honesty and integrity of the vendor. You can tell a lot about the details they give in their ad and the accompanying pictures. You see some ads you wouldn’t go anywhere near!
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