Dying one by one - long but please read, I'm terrified!

Hello,

I have raised chickens for many many years and I have never encountered anything like what is now happening with my flock. I know where i made my mistakes and I am not here to be chastised or put down, so please try to help me regardless of what you feel i did wrong.

I had 18 hens from a hatchery that I have raised from 3 days old, they are now 18 months old and have been going through their first molt. Everyone has been healthy, happy and eating/drinking and pooping normally.

We had a very large coop built in order to accommodate up to 30 hens so I ended up buying 10 additional English Orps from a neighbor. These hens were varied in age from 8 weeks to 3 months. All large enough to hold their own. We kept them near the original flock but separated by fencing for a week.
Then we let them all free range together on our 6 acres and go home into the coop together. The following week was extremely hot. Near 100 degrees with 100% humidity and the dying started. It was always the new hens that were dying despite all of the cooling measures that we had in place. And as much as chickens enjoy a little cannabalism, they have never touched the dead hens. At the same time, all egg laying stopped in its tracks. I went from getting on average a dozen eggs a day to ZERO. This was July and there were always feathers all over the pen and yard. At this point I asked my neighbor if his hens were vaccinated for Mareks and he said that they are not. OMG! WHAT HAVE I DONE!

At first they were dying 1 hen every day or 2 days for the first week. I lost 5 that first week. Then it stopped for a while.
In August, I lost 3 more in the same manner. AGAIN, all the English Orps i had just bought. I worked away from home and never saw the hens in the interim, just found the bodies.

Now I work at home and am watching the girls very closely.
I have lost 2 more hens in the last 2 weeks. And now I know the symptoms.
2 to 3 days prior to their death, the hen stops perching and stays on the floor of the coop at night. Still eating and drinking.
The next day they are seemingly becoming slowly paralysed on one side of the body.
The next day they die.

Today it was one of my own hens that i raised from the hatchery that was vaccinated.
There are no mites or lice
The eyes, nares and mouth are clear
There are no sores or lumps on the skin

Am I going to watch my entire flock die from Mareks?
Please help me figure this out. There are no vets in my area for chickens.

 

Thank you everyone for your replies. When you ask about pictures, I will post some, but only of those that are healthy and their coop/run and basic forage area. I have not taken any photos of the dead or dying but can in the future if I am not done with this yet. Please God, let this end now.....

They are free to forage on the entire 6 acres but stay mainly in the area around their coop which is surrounded by large trees. In the sun they dust bathe, bask in the sun or go under the trees. These are old growth evergreen and hardwoods.

They eat only Organic feed and scratch from a local grainary. Same food from day 1 with me. I do give them kitchen scraps like potato peels, fruit, greens. They don't get rotted human food, if I wouldnt eat these kitchen scraps, my birds dont get them either.

It has been VERY wet here in Southern Wisconsin. Lots of mushrooms growing in the grass. Hens are always scratching and picking through grass and eating God knows what. They have no access to chemicals or poisons on any kind. There is bound to be mold in a lot of places outside due to so much rain, but nothing that i can pin point.

I had a total of 28 hens, 18 of my hatchery raised and 10 Eng Orps from the neighbor.

I have 15 of my original hatchery hens. 2 taken by a coyote and 1 died yesterday from this horrific illness.

Of the 10 Eng Orps i bought, I have 2 left. All others died of this horrible thing.
Of the 2 that are left, 1 was the youngest of those i bought and the other is the oldest of the 10 i bought. They seem healthy at this time.

I have not sent any one in for neceopsy and guess I'm not sure who that would be? Our state lab? I am just dumbfounded by this. I have never had so much as a car of bumblefoot. I am a RN by profession and meticulous about keeping their coop and run clean.

Just the fact that no one is totally convinced this is Mareks gives me some hope that I can save some of these birds.

Again, thank you all very much!