Alopecia means hair loss. There are different types of hair loss, each with a different name:
Losing all hair on the scalp or body only happens to about five percent of people.
Hair often grows back but may fall out again. Sometimes the hair loss lasts for many years.
Alopecia is not contagious. It is not due to nerves. What happens is that the immune system attacks the hair follicles (structures that contain the roots of the hair), causing hair loss. This disease most often occurs in otherwise healthy people.