Little white parasites in my chickens?

[Luciana069]

I spotted a very small white "parasite" very close to my chicken's eye. It was white and it was smaller than a flea. I barely saw it.
Could it be a dangerous parasite?
I'm worried because one of my three chickens is looking not very good. I saw her sitting on the ground some days ago. She also seem to have less appetit than the others, drinks a lot of water and spend much time scratching her feathers. I didn't find the white "parasite" in that hen (the one that looks sick), but I thought it could be in all the chickens just that is affecting her first.

 

[orloffer]

Check them all for poultry lice. I have not had it in my flock, but it is very common.

 

[dawg53]

Yep, lice. Inspect the vent area and you'll see them crawling around. Also look for lice eggs attached to feather shafts. The eggs can be removed with coconut oil. Use Permethrin dust to dust your birds or spray them with Permethrin 10% liquid concentrate mixed in water. The mixing instructions are attached to the container.
Clean out your coop and spray inside the coop including roosts and nest boxes. The liquid Permethrin has a 28 day residual.

 

[aart]

Sounds like it could be lice.

Might depend on.....
Where in this world are you located?
Climate, and time of year, is almost always a factor.
Please add your general geographical location to your profile.
It's easy to do, and then it's always there!

Check them over real well for mites and/or lice?

Google images of lice/mites and their eggs before the inspection so you'll know what you're looking for.

Part the feathers right down to the skin around vent, head/neck and under wings.

Best done well after dark with a strong flashlight/headlight, easier to 'catch' bird and also to check for the mites that live in structure and only come out at night to feed off roosting birds.

Wipe a white paper towel along the underside of roost to look for red smears(smashed well fed mites).

Good post about mite ID by Lady McCamley:
https://www.backyardchickens.com/threads/my-chicken-has-mites-now-what.1273674/page-2#post-20483008