Any bacteria do not cause psoriasis. No virus or fungus causes it. It is not a contagious disease. There is nothing but body that decides if you will get psoriasis or not. A gene is responsible for psoriasis. Those who have that gene may get psoriasis if it is triggered. Psoriasis - common triggers The common triggers of psoriasis are sunburn, stress, skin injury, some medications, infections, smoking, drinking, and change in weather. Any of these can trigger psoriasis in a person who has the faulty gene. The gene makes skin act abnormally. Again it is not necessary that every time the triggers will work. Sometimes they don't while sometimes a small trigger flares up psoriasis. Talking about the gene, not all siblings get psoriasis. It can be hereditary many times. As we discussed, for getting psoriasis you need a faulty gene and a trigger. Many healthy persons who show no sign of psoriasis sometimes get a small injury and the skin does not heal. After some days, the doctors find out that the person has psoriasis, which is not allowing the skin to heal. The strange behavior of skin at certain places on the body is responsible for psoriasis. Skin misbehaves at the command of a gene. Let us see how skin acts differently in psoriasis. Psoriasis - skin action in psoriasis In our skin the bottom layer produces new cells. These new cells take up to a month to travel to the top and the dead cells from the top are shed off. We can say that the skin renews itself every month. What skin cells you have today are not those you were born with. Old cells die and new cells are born. That way our whole body renews itself. In psoriasis skin, the speed at which skin brings up the new cells and sheds the old increases many fold. The cells are shed every third or fourth day instead of a month. This creates the red patches, flakes and itching. The skin misbehaves at the command of a gene. Every treatment aims towards providing relief to itching, removing the flakes and slowing down the process of skin cells coming up. This article is only for informative purposes. This article is not intended to be a medical advise and it is not a substitute for professional medical advice. Please consult your doctor for your medical concerns. Please follow any tip given in this article only after consulting your doctor. The author is not liable for any outcome or damage resulting from information obtained from this article.