They will bite humans, and if you have that many bites that quickly, unless you live in an area heavily infested with mosquitoes I personally would treat for parasites regardless. I have never heard of anything that can be transferred to humans by mites, just itchy bites, but it isn't something I've researched either. The chickens they can harm, especially if there are a lot of them, they suck their blood and if there are enough of them it can kill the birds.
Discard the bedding, spray the coop down with permethrin and let it dry and then rebel with fresh shavings; dip or spray all your birds with permethrin, or dust them with permethrin powder. Repeat in 7 days for treating the birds, and you may have to spray the coop daily to kill all the newly hatched mites if it's a bad infestation.
If it turns out to not be mites but some other critter the permethrin will probably take care of it. You can usually find them in the coop in spaces where two pieces of wood meet, little tiny moving dots.