Is psoriasis contagious disease?

No. Psoriasis is a chronic, non contagious, inflammatory, autoimmune disease, with the genetic predisposition, and can be triggered by various environmental factors (infection, medication). And psoriasis develops when the immune system mistakenly sends signals to the skin cells to speed  multiplication. The entire cycle of skin cells, in this situation lasts a few days insted of several weeks. And immature keratinocytes do not peel from the skin, forming a psoriatic plaque. But touching these lesions, you can not get infected.