A desert is a region of land that is very dry because it receives low amounts of precipitation (usually in the form of rain but may be snow, mist or fog), often has little coverage by plants, and in which streams dry up unless they are supplied by water from outside the area.
Alopecia areata is an autoimmune disease. Autoimmune means that the body's immune system attacks the body. When alopecia areata develops, the body attacks its own hair follicles. A person's genetic makeup, combined with other factors, triggers this form of hair loss.
The most common pattern is one or more well-defined spots of hair loss on the scalp. There is also a form of more generalized loss of hair referred to as diffuse alopecia areata throughout the scalp. Occasionally, all of the scalp hair is lost, a condition referred to as alopecia totalis. Less frequently, the loss of all of the hairs on the entire body, called alopecia universalis, occurs. Alopecia areata tends to occur most often in adults 30 to 60 years of age. However, it can also affect older individuals and, rarely, young children. Alopecia areata is not contagious.