Psoriasis is a disease whose main symptom
is gray or silvery flaky patches on the skin which are red and inflamed
underneath. In the United States, it affects 2 to 2.6 percent of the
population, or between 5.8 and 7.5 million people. Commonly affected areas
include the scalp, elbows, knees, arms, stomach and back. Psoriasis is
autoimmune in origin, and is not contagious. Around a quarter of people with psoriasis
also suffer from psoriatic arthritis, which is similar to rheumatoid arthritis
in its effects. Psoriasis was first given that name in complete differentiation
from other skin conditions by the Austrian dermatologist Ferdinand von Hebra in
1841, although there are what are believed to be descriptions of the disease in
sources going back to ancient Roman and possibly even biblical times.
