Now I see that we are talking about a different desease. Mange is caused by a mite that cannot be seen by the human eye. No lumps involved, just a mites under the skin of an animal. Take a look at these links. Not very pretty as well. Got to feel sorry for these infested tree rats.
http://www.michigan.gov/dnr/0,1607,7...6949--,00.html
And:
http://www.flickr.com/photos/mandj98/349107973/
Now, my question is when you encounter a squirrel like this, do you shoot him or let nature take it's course. I understand that nature isn't hardly ever merciful.
Be safe !!!!