leprosy:

chronic granulomatous communicable disease occurring in tropical 
and subtropical regions; characterized by inflamed nodules beneath 
the skin and wasting of body parts; caused by the bacillus 
Mycobacterium leprae 
A chronic mycobacterial disease that is sometimes infectious. It 
primarily affects the peripheral nervous system and secondarily 
involves the skin and certain other tissues. If untreated, there 
can be progressive and permanent damage to the skin, nerves, limbs 
and eyes.