Life after Marek's ???

[jaimedes]

I have lost two pullets in the last few months, presumably from the dreaded Marek's. Two different vets were used for the 2 different birds and both suspected Marek's but no necropsy was performed. Both came from a local breeder who says they were vaccinated for Marek's. Prior to that I had 4 girls that I had for about 8 months before getting the 2nd group that came from a hatchery (vaccinated for M) who are still quite alive and quite healthy. I have one bird out of 3 left from the local breeder who looks healthy.
Question is this... is it ever safe to add new birds? I am ordering 3 pullets, also vaccinated, but am fearful. I have read the FAQ's about Marek's on this site and many forum threads regarding the disease. The FAQ said that even vaccinated birds would get the disease if it is present (which it seems to be). WHAT???!!!??? How do you ever add new birds if that is the case?
Any insight into this or advice on how to add new girls safely would be most welcome.

 

[Lady of McCamley]

Adding birds is a risk but not unwarranted, in my opinion. It is simply the normal risks you take with birds as Marek's is considered to be very common in the general environment. A mixed flock is the best protection from a flock wide Marek's disaster.

So choose from breeds that are naturally resistant and add birds that have been vaccinated to lower your chances of a flock wide losses. That's the best anyone can hope for. You may lose some from time to time, but you will have many healthy flock members too.

Selling or re-homing birds from your flock is more problematic. If you truly have active Marek's, obviously you don't want to pass that along to others and would need to keep a closed flock. However, there are those buyers who would be interested in birds (survivors) who have proven to be naturally resistant or whose vaccination immunity is showing strong. Full disclosure would be important so the buyer can judge if it is worth risking their current birds to gain (and breed from) ones that may be Marek resistant.

I think this way because of the facts surrounding Marek's.

All flock owners should consider their birds have been exposed to Marek's as it is so prevalent in the general environment.

Marek's is a virus that causes tumors to grow in birds that do not have natural resistance, in other words, those that do not keep the virus in check.

Marek's comes in many different strains (like the cold virus). Which means the vaccination does not address all strains. Also, the vaccination is "leaky." It prevents, or slows, the tumor growth, but does not prevent actual infection of Marek's.

Currently there are two lines of thought. Generally those birds vaccinated for Marek's have the best chances of not succumbing to tumors. However, there is growing concern that the vaccine, being leaky, is causing (through natural selection) a super virus to brew.

Many in the industry now recommend breeding Marek's resistant birds rather than relying on the leaky vaccine. That means breeding from those birds who have been exposed to Marek's but show no symptoms (over a long term).

So that means buying and selling non-vaccinated birds that appear healthy but have no guarantee against Marek's as there is none. Obviously that means accepting some risk as well.

You could compare it to the virus that causes cold sores in humans. It is ever present in the environment but not everyone develops cold sores. I've never had one. My husband however, is very prone. He has learned to take certain vitamins and watch his lifestyle so that he doesn't lower his immune system.

Likewise with your birds. As the Marek's virus is considered to be ever present in the environment, every bird could potentially harbor the virus, but not every bird will develop the tumors unless some stressor lowers their immune system.

So my line of thinking is purchase a variety of Marek's resistant breeds. Purchase some vaccinated birds. Then I do my very best to take good care of my birds to keep their stress low (clean litter, food/water, regular worming/parasite management, plenty of room).

I even make a point to purchase some chickens (my brooding Cochin bantams) from a turkey breeder since turkey's carry the turkey strain (which the original chicken vaccines were made from).

So hopefully I've diversified my flock well enough that my losses will be only a few over the years. If I sell or re-home, I make sure the buyer/receiver knows they've been exposed over the years to Marek's, but that they appear to be resistant to the strains in my area. However, they should keep the birds in isolation before introducing, and they need to understand adding any new birds to an existing flock brings risk.

The other option is to keep a closed flock. Birds coming in but no birds going out. Older birds are either culled (killed) or kept until they die of natural causes.

My thoughts.
Lofmc

 

[jaimedes]

"So choose from breeds that are naturally resistant and add birds that have been vaccinated to lower your chances of a flock wide losses. That's the best anyone can hope for. You may lose some from time to time, but you will have many healthy flock members too."

"So my line of thinking is purchase a variety of Marek's resistant breeds. Purchase some vaccinated birds. Then I do my very best to take good care of my birds to keep their stress low (clean litter, food/water, regular worming/parasite management, plenty of room)."





Thank you, there is a lot of insight in your response and I appreciate the time you took to write it. Is there a resource that you are aware of that would help me figure out which breeds are more resistant to the virus?

 

[Lady of McCamley]

From what I've read, Fayoumis are known to be naturally Marek's resistant.

Most commercial production lines are bred for Marek's resistance, although they also rely on vaccination. I have read several studies that indicate several White Leghorn strains are very resistant as are several White Rock strains, but you would have to get the correct strain.

It depends on the hatchery. Many simply breed for production and have stock with weaker immune systems.

I have read that Bantam Cochins are more Marek's resistant while Silkies are not. They are very Marek's prone as are Sebrights. Cream Legbar have been problematic. The original imports died from Marek's, but the subsequent lines imported were stronger.

I can personally attest my Silkie died of Marek's while her coop mate, a bantam Cochin was unaffected. I'm waiting on my Cream Legbar growouts.

Bottom line, the one breed that came up again and again for resistance was Fayoumi. After that, it is hatcheries with resistant lines. For small private breeders, it is breeding from the strong survivors after an out break which means keeping careful breeding lines. Hybrid vigor may help especially if one of the parent stock is resistant.

I'll link an especially comprehensive article below about Marek's.

LofMc

http://www.birdhealth.com.au/mareks-disease

 

[jaimedes]

Thank you again Lady of McCamley, very useful information. I feel like a may be an MD expert shortly (unfortunately).
I do have bats that live in my barn (where my birds that have died have their indoor coop space), I never asked my vet, but have you ever heard of bats carrying anything that can cross infect species? I realize they aren't birds, but just have a nagging curiosity about it since I have found 3 dead ones in my barn in the last month. These were the first bat mortalities I have seen in the almost two years I have lived there. It is most likely coincidence.

 

[Lady of McCamley]

*Most* diseases are species specific and do not cross over.

However, having said that, bats are also known to harbor viruses, such as rabies, that do infect other animals.

Further, their droppings, along with the chickens, can harbor diseases that produce lung illness in humans (histoplasmosis).

They also can be vectors of mites and such, carried on their fur.

So while it is likely a coincidence that you have dead bats and dead chickens, I would not rule out that some disease transition may have occurred.

While bats are very helpful in ridding insect pests, I personally would get rid of the bats in the barn or put the chickens in another area.

LofMc

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1539106/
https://www.cdc.gov/niosh/docs/97-146/default.html

 

[orrpeople]

Adding birds is a risk but not unwarranted, in my opinion. It is simply the normal risks you take with birds as Marek's is considered to be very common in the general environment. A mixed flock is the best protection from a flock wide Marek's disaster.

So choose from breeds that are naturally resistant and add birds that have been vaccinated to lower your chances of a flock wide losses. That's the best anyone can hope for. You may lose some from time to time, but you will have many healthy flock members too.

Selling or re-homing birds from your flock is more problematic. If you truly have active Marek's, obviously you don't want to pass that along to others and would need to keep a closed flock. However, there are those buyers who would be interested in birds (survivors) who have proven to be naturally resistant or whose vaccination immunity is showing strong. Full disclosure would be important so the buyer can judge if it is worth risking their current birds to gain (and breed from) ones that may be Marek resistant.

I think this way because of the facts surrounding Marek's.

All flock owners should consider their birds have been exposed to Marek's as it is so prevalent in the general environment.

Marek's is a virus that causes tumors to grow in birds that do not have natural resistance, in other words, those that do not keep the virus in check.

Marek's comes in many different strains (like the cold virus). Which means the vaccination does not address all strains. Also, the vaccination is "leaky." It prevents, or slows, the tumor growth, but does not prevent actual infection of Marek's.

Currently there are two lines of thought. Generally those birds vaccinated for Marek's have the best chances of not succumbing to tumors. However, there is growing concern that the vaccine, being leaky, is causing (through natural selection) a super virus to brew.

Many in the industry now recommend breeding Marek's resistant birds rather than relying on the leaky vaccine. That means breeding from those birds who have been exposed to Marek's but show no symptoms (over a long term).

So that means buying and selling non-vaccinated birds that appear healthy but have no guarantee against Marek's as there is none. Obviously that means accepting some risk as well.

You could compare it to the virus that causes cold sores in humans. It is ever present in the environment but not everyone develops cold sores. I've never had one. My husband however, is very prone. He has learned to take certain vitamins and watch his lifestyle so that he doesn't lower his immune system.

Likewise with your birds. As the Marek's virus is considered to be ever present in the environment, every bird could potentially harbor the virus, but not every bird will develop the tumors unless some stressor lowers their immune system.

So my line of thinking is purchase a variety of Marek's resistant breeds. Purchase some vaccinated birds. Then I do my very best to take good care of my birds to keep their stress low (clean litter, food/water, regular worming/parasite management, plenty of room).

I even make a point to purchase some chickens (my brooding Cochin bantams) from a turkey breeder since turkey's carry the turkey strain (which the original chicken vaccines were made from).

So hopefully I've diversified my flock well enough that my losses will be only a few over the years. If I sell or re-home, I make sure the buyer/receiver knows they've been exposed over the years to Marek's, but that they appear to be resistant to the strains in my area. However, they should keep the birds in isolation before introducing, and they need to understand adding any new birds to an existing flock brings risk.

The other option is to keep a closed flock. Birds coming in but no birds going out. Older birds are either culled (killed) or kept until they die of natural causes.

My thoughts.
Lofmc

What would be your opinion of selling hatching eggs or incubating chicks for sale. I realize infected dander could be anywhere...

 

[Lady of McCamley]

What would be your opinion of selling hatching eggs or incubating chicks for sale. I realize infected dander could be anywhere...

Hatching eggs for sale are fine as the virus does not penetrate the shell.

Chicks are more problematic. It depends on where they are incubated. By hen? Or sterile brooder far away from the flock.

You could also sell with full disclosure...non vaccinated chicks bred from Marek's resistant stock.

Or vaccinate the chicks at a day old and keep them away from the flock as it takes the vaccine a couple of weeks to take effect.

Marek's is assumed to be so prevalent that almost all birds have been exposed, but when selling, care and disclosure would be important.

 

[orrpeople]

Hatching eggs for sale are fine as the virus does not penetrate the shell.

Chicks are more problematic. It depends on where they are incubated. By hen? Or sterile brooder far away from the flock.

You could also sell with full disclosure...non vaccinated chicks bred from Marek's resistant stock.

Or vaccinate the chicks at a day old and keep them away from the flock as it takes the vaccine a couple of weeks to take effect.

Marek's is assumed to be so prevalent that almost all birds have been exposed, but when selling, care and disclosure would be important.

Yes, I am thinking along the same lines...but still trying to make an informed decision with my flock, as my diagnosis is so new. I have 4 lovely breeding groups of rare/semi-rare birds and now this....
My Cream Legbars seem especially susceptible to the disease. I have one more with symptoms this morning. Will probably cull her early. I have two that are laying eggs though, so perhaps they may be a bit more resistant? Only time will tell. I also lost a Bielefelder- so am wondering about them as well.
If you have any other words of wisdom, I would be grateful for them. I'm giving myself a week to weigh all my options (from the extreme: cull them all - to trying to figure out a way to live with it but do no harm to anyone else.)
Thank you for all you well informed earlier posts, they have really given me food for thought.
-Kathy

 

[Lady of McCamley]

Yes, I am thinking along the same lines...but still trying to make an informed decision with my flock, as my diagnosis is so new. I have 4 lovely breeding groups of rare/semi-rare birds and now this....
My Cream Legbars seem especially susceptible to the disease. I have one more with symptoms this morning. Will probably cull her early. I have two that are laying eggs though, so perhaps they may be a bit more resistant? Only time will tell. I also lost a Bielefelder- so am wondering about them as well.
If you have any other words of wisdom, I would be grateful for them. I'm giving myself a week to weigh all my options (from the extreme: cull them all - to trying to figure out a way to live with it but do no harm to anyone else.)
Thank you for all you well informed earlier posts, they have really given me food for thought.
-Kathy

No...don't cull them all! Breed from those that are resistant!

And if you haven't done so yet, send the bird with the most obvious symptoms to an Ag lab for necropsy. A definite diagnosis would really help your business plans. There are other things that can mimic Marek's.

Yes, Cream Legbars are susceptible. The first breeding pairs (I think that Greenfire Farms brought over) all succumbed to Marek's in the US. Later stock was better, but the breed is known to have problems with it.

I lost a Cream Legbar x Barnevelder cross to what I am pretty sure was Marek's, though both hens that could have been her mother (CL's) never showed signs.

I'll link some information for you about how the industry is encouraging breeding for resistance rather than relying solely on the vaccine.

Informing buyers is the important thing. However, that also means being fully informed. Many buyers are aware that Marek's is part of the atmosphere, and all chickens are considered exposed. Many are interested in chicks from resistant flocks rather than chicks who have been vaccinated.

Personally, I would cull those who are severely affected. Clean your coops thoroughly. Watch for those who show no signs, and breed from them. Then sell the fertile eggs, which in themselves are profitable. (The cheapest I can find around here was $3 an egg, or $20 a dozen...better lines are $5 an egg).

The nice thing about selling fertilized eggs is there is less risk on your part, and no transmission of Marek's possible.

After your line settles, and you have no sign of Marek's for a generation, or two, then you can sell chicks...unless you decide to incubator hatch chicks and immediately vaccinate them for sale...keeping the unvaccinated chicks for the next generation of breeding, or you could decide to vaccinate all chicks (or eggs at day 18).

It is very frustrating...I know.

LofMc

https://www.pbs.org/newshour/science/tthis-chicken-vaccine-makes-virus-dangerous

http://www.merckvetmanual.com/poultry/neoplasms/marek’s-disease-in-poultry