Sick chickens - help needed asap for a diagnosis.

We have our first infectious disease outbreak in our flock and have so far been unable to positively ID the cause. Could really use some help.

We have had two birds die in the past 3 days, and have a third one sickening. Sick birds have been isolated, but what ever it is is still spreading.

Symptoms - blue/purple discolouration to the comb, general listlessness which progresses over about 24 hours to being unable to move around. Wings drooping down. Sleeping on the ground instead of roosting.

We are on high alert due to avian flu in this area, but I spoke to the person from DEFRA who seemed to think ours was not likely a high risk case and to keep separating sick birds and monitoring.

I really want to know what this thing is. Any ideas what I can do to test?  This is our first flock, and these brids are about 18 months old.

This sounds pretty awful, Michael. The symptoms, especially the discoloured combs, drooping wings and lack of mobility are all signs of Marek's Disease:

https://www.thehappychickencoop.com/mareks-disease/

Once this is in your region, it's spread continually by wild birds and about impossible to get rid of. You can vaccinate developing chicks while they're still in the egg but it is not cheap for the smallholder (commercial operations do it as a matter of course in NZ).

The good news (if you call it that) is that many or most of your chickens are likely to develop immunity and after that happens what you will probably see is a handful of cases each year. Chicks will usually succumb, but strong adult birds often come right after a few days and go on to live normal productive lives. I've had a couple hens that I found in the ditch, fully paralysed, that recovered after a couple of days in quiet and warm respite boxes. One is sitting on a clutch of eggs at the moment.

Thanks Phil, that is really helpful. With your suggestion of Marek’s I have done some more digging and it does seem to fit.

You mention that chicks are vulnerable, but that you have some brooding right now. Do a reasonable number make it to adulthood, or do you expect really high chick mortality?

We've had to live with Marek's ever since we started raising chickens here and the most we ever lose from our broods is usually 15-20%. Predation by cats and hawks is more of an issue here, as is inexperienced mother hens (one decided to go back to roosting in a tree when her chicks were only a few days old...they died of exposure when it rained hard one night).