psoriasis that causes stiffness is it contagious
1 Psoriasis is not contagious. 2  Psoriasis is a condition of the immune system. 3  The severity of psoriasis is based on how it affects you and how much of your body is covered. 4  About 1 in 5 people with psoriasis have moderate to severe plaque psoriasis.soriasis is a lifelong condition of the immune system. The exact cause is unknown; however, researchers think that family history, environment, and the immune system can all play a role in psoriasis.