I hope someone can help me.  I am cosmetologist, not a professional make-up artist for stage and theater.  But I have been asked to head up hair and make-up for an amatuer production.  Mid-scene, on stage, a character is struck with leprosy on his face.  The leprosy is supposed to make the flesh look white and rotted.  The actor has a matter of seconds to change his appearance.  I was wondering what would be the best method for simulating this. 

Well.. let's see

I assume you're speaking of this year's convention.  i play the leprous part in ours.  i have a couple of ideas.  You?

I'm a little late replying but we did figure out what to do.  I made  a mask form using liquid latex and  painted it with  fabric 'puff ' paint in white.  Once I had steamed the paint to create the dimension and texture of infected skin  I ripped some of it away from the latex mask and used bright red and dark brown paint to make those 'open areas' look like open sores.    I attached a thin peice of elastic so He could wear it on his head.  He kept it hidden under a hat, then mid scene knocked the hat off and pulled the mask down while his back was to the audience.  Pretty gross but very effective!  Jandcries, it was at a convention.  The account of  Gahazi.