There are several different types of alopecia with different names and different causes. Alopecia areata is the best known—it’s like an inexplicable spot baldness anywhere on the body, but often on the head. Alopecia areata affects about 2% of the population in the United States.
A rarer form of alopecia is alopecia universalis, which in Europe affects about one person in 4000 or 0.025% of the population (we don’t have reliable statistics for the US). In alopecia universalis, the person loses all the hair on the body. Aside from the psychological effects, which shouldn’t be discounted, the physical effects of total hair loss are considerable. Imagine having no eyelashes to protect your eyes or no nose hairs to protect and filter your airways.