In New Testament times, it was normal to group all disfiguring diseases, whether curable or not, under the term 'leprosy'.
Strictly speaking, leprosy (Hansen's disease) is a specific disfiguring disease that results in total loss of feeling, such that sufferers are likely to injure themselves, even breaking off fingers, without realising they had done so. Leprosy is mildly contagious but with modern treatment is curable.
Psoriasis is a chronic autoimmune disease that appears on the skin, and occurs when the immune system sends out faulty signals that speed up the growth cycle of skin cells. Quite different to leprosy in cause and effect, Psoriasis is not contagious.
The word "plague" has two meanings. "The Plague" is a specific disease, or rather a series of specific diseases: bubonic plague, pneumonic plague etc. On the other hand "a plague" is any rapidly spreading epidemic. The King James Bible, contemporary with Shakespeare, talks about "the plague of leprosy", and obviously leprosy and plague are two very different diseases. It is this secondary sense which Mercutio uses in his curse: he is wishing some unspecified epidemic disease on the Montagues and Capulets, not the specific disease called "the plague".
The black death (plague) it killed 70% of the population in Brema, and even more in other places) and leprosy
psorasis
I do not have leprosy.
unicellular organisms
Some people are genetically resistant to leprosy, probably and no matter what, they do not get leprosy. Other with tuberculous type of leprosy have high resistance to leprosy. Those with lepromatous type of leprosy have least resistance to leprosy germs. The intermediate leprosy type have intermediate resistance to leprosy germs. Body reacts to leprosy by trying to kill the leprosy causing germs. There is an inflammatory response.
no
LEPROSY "worse than acne)
No you can not catch leprosy by a cockroach.
leprosy is a pandemic disease
No, it is called Mycobacterium leprae!http://www.medicinenet.com/leprosy/page2.htm#causes
leprosy causes your skin to rot away.