Are my chickens in danger?!

[arihen]

My black australorp hen passed away unexpectedly about a week ago while I was away, she showed no signs of disease or anything. I’m worried for my 3 other hens, they all seem energetic and fine but one has stopped laying entirely, another has strange breakage in her feathers so she looks a bit skinny. I gave them some depurox about 3 days ago… haven’t seen any worms in stool though. They have chicken lice!

 

[ChickyCh00k]

Have you treated for the lice? An infestation can cause stress and health issues.

 

[Wyorp Rock]

My black australorp hen passed away unexpectedly about a week ago while I was away, she showed no signs of disease or anything. I’m worried for my 3 other hens, they all seem energetic and fine but one has stopped laying entirely, another has strange breakage in her feathers so she looks a bit skinny. I gave them some depurox about 3 days ago… haven’t seen any worms in stool though. They have chicken lice!

Sorry for your loss.

Without a necropsy, there's really no way to know why a bird died.

You have another thread asking about the feather loss, it can be found in the link below. You've noticed lice, so it's best to treat all the birds to get the parasites under control.
https://www.backyardchickens.com/threads/strange-feather-loss.1600587/#post-27221839

If you suspect they have worms, getting a fecal float will confirm whether they need to be dewormed or not.
If you wish to deworm them without a fecal float, then use an anthelmintic like Safeguard (Fenbendazole) or Valbazen (Albendazole) to treat your flock. "Natural" supplements like Depurox will not be an effective dewormer.