Blackhead wiping out chicks fast

[SpookZoneSpooker]

I'm in urgent need of help. I bought two Black Australorp from a reputable feed store. I quarantined them, they showed no signs of any illness. What I didn't know is they both had dormant histomoniasis. The peachicks interacted with them before I knew they had it, killed them within two days. It's starting to spread around my other chickens like wildfire, and I'm worried it's going to spread to my adult Peas very soon. All of them are free ranged, and I cannot stop them from interacting. I need urgent treatment to try to save my flock, any help is greatly appreciated.
Thank you for your time.

 

[Midnightman14]

If it's killing your chickens to it probably isn't blackhead.

 

[BirdsBeesTrees]

 

[ChickNanny13]

Would it be possible to take/send a carcass to a vet/lab to determine what really killed them? Sorry for you losses & wish I knew more Hopefully someone will.

http://www.vetdna.com/test-type/avian-bird
https://www.metzerfarms.com/PoultryLabs.cfm

 

[007Sean]

I agree with @Midnightman14
Have you had a necropsy done on the pea chicks that died? Have you had histopathologic test (blood tests)done on the the suspected birds.
Are your birds showing any signs, such as, listlessness, drooping wings, yellow colored droppings.
Blackhead, historically hasn't caused mortality in chickens, except for very young chicks. Older birds may be infected for quite sometime before symptoms appear, usually an emaciated appearance is commonly seen in older birds.

 

[KsKingBee]

I agree with Sean and Josh, also considering that there was not enough time for the transference to the chicks and to bring them down. I would lean towards cocci as being the problem.