AKA Demodecosis, Demodex, demodectic acariasis, follicular mange, and red mange.
Demodectic mange is the result of mites of the Genus Demodex multiplying out of control. Small populations of these mites are present in healthy animals (dogs, cats, pigs, humans, rabbits, cattle, etc, etc.), but occasionally a population will rocket out of control. This is most likely due to a problem with the host's immune system. This results in irritation, hair loss, inflammation, and thickening of the skin.
The Demodex mite is too small to be seen without a microscope, 0.1-0.4 mm long. Demodex infests a number of mammals, each type of animal having a different species of Demodex to infest it. It lives in hair follicles or the secretory ducts of sebaceous glands connected to the hair follicles; the female lays her eggs there, and when they hatch the larvae and nymphs are swept by the sebaceous flow to the mouth of the follicle. Here they mature, and travel to other hair follicles to begin the cycle again. The entire life cycle takes about three weeks. Since all members of a host's species tend to have some Demodex mite, demodectic mange is not considered contagious. It cannot move between species.
Demodex folliculorum = Humans (in the hair follicles)
Demodex brevis = Humans (in the sebaceous glands)
Demodex phylloides = Hog mange (Pigs)
Demodex canis = (Dogs)
Demodex bovis = (Cattle)
Demodex ovis = (Sheep)
Demodex caprae = (Goats)
Demodex cati = (Cats)
Etc.
Phylum Arthropoda
Class Arachnida
Order Parasitiformes
Suborder Prostigmata