A threshing floor in Santorini in Greece. Russian women using a hand powered winnowing machine in a barn. Note the board across the doorway to prevent grain from spilling out of the barn, this is the origin of the term threshold.
Psoriasis is not contagious. It is not something you can âcatchâ or that others can catch from you. Psoriasis lesions are not infectious and cannot be passed from person to person.It is okay to have contact with people who have psoriasis.t is not something you can âcatchâ or that others can catch from you. Psoriasis lesions are not infectious and cannot be passed from person to person. It is okay to have contact with people who have psoriasis.
Certain factors may trigger psoriasis in a person who has never had symptoms before. And for those who have psoriasis, these same factors can trigger another bout with the disease. Triggers include: 1  bacterial or viral infections, such as strep throat or the common cold. 2  diseases that weaken your immune system, such as AIDS or cancer. 3  emotional stress. 4  dry air or dry skin (particularly from changes in weather). 5  some medicines, such as beta-blockers, lithium, and anti-malaria drugs.