Spiritual plagues are widespread infestations of highly contagious and deadly attitudes. The spiritual analogues of The Black Death and all the other biological plagues have existed at least as far back in time as we have records, and no doubt much further. The major feature of any type of spiritual plague is that the infected seldom recognize their condition but actually identify with and enjoy passing on the disease. It is in the very nature of this category of diseases to replicate through the enthusiastic and willing participation of the infected. Unlike physical diseases, these invisible plagues depend on the host misinterpreting the presence of the parasite as a positive and life-enhancing addition. Their method of replication relies on the inability of their hosts to identify them as diseases at all. source.