Psoriasis

This skin disorder that affects around two percent of Americans has nothing to do with germs or bacteria. “Psoriasis is an autoimmune condition in which the immune system attacks the skin,” explains Dr. Adalja. “It is not caused by a microorganism that can be passed between people.” Telltale signs include red, itchy patches of skin topped by white or silvery scales that are often found on the elbows, knees, and scalp; they occur when the body creates and accumulates new skin cells too quickly. Don’t miss these 6 surprising signs of disease your skin can reveal