Leprosy patient, Manila, Philippines,1899. Leprosy, also known as Hansen's disease, is a neurological disease caused by the bacterium Mycobacterium leprae. It results in damage to the nerves leading to disfiguring skin lesions, deformities, and loss of the extremities. The disease is spread by droplet infection, but it is not very contagious and is now curable with medication. It occurs more commonly among those living in poverty, and historically sufferers were often stigmatised and segregated.