You're welcome. Well draining soil, weeds and vegetation cut back, a dry coop environment with good ventilation, not allowing the accumulation of droppings under roosts or within the confines of the yard, removal of wild bird nests on property, control of rodent populations, preventing wild birds from pilfering poultry feed troughs, clean water up high enough to keep from getting fouled, are all things you can do to prevent problems you are experiencing.
I've found doing a thorough cleaning by removing old shavings every 3-4 months, treating coops with an effective emulsified concentrate premise insecticide will keep mites/lice off the birds.