Leprosy

It was 1873, and Dr. Armauer Hansen of Norway had astounding news for the world: leprosy was caused by a bacterium (Mycobacterium leprae). Until then, the disease was thought to be from a curse or sinful ways.

Not very contagious
Modern medicine knows that leprosy is spread when an untreated infected person coughs or sneezes (but not by sexual contact or pregnancy). However, leprosy is not very contagious; approximately 95% of people have natural immunity to the disease. People with leprosy who are treated with medication do not need to be isolated from society. (Historically, people with leprosy were sent to "lepers' colonies" on remote islands or in special hospitals.)

Signs and symptoms
The earliest sign of leprosy is commonly a spot on the skin that may be slightly redder, darker, or lighter than the person's normal skin. The spot may lose feeling and hair. In some people the only sign is numbness in a finger or toe.

If left untreated, leprosy has serious effects on the body, including:

Hands and feet - Leprosy bacteria attack the nerves in the hands and feet and cause them to become numb. A person may get cuts or burns on the numb parts and not know it, leading to infections which cause permanent damage. Fingers and toes may be lost to infection. Serious infections in the feet may require amputation. Paralysis may cause the fingers and toes to curl up permanently.
Eyes - Leprosy bacteria attack the nerves around the eyes causing the loss of blinking reflex (which protects the eye from injury and moistens the surface). The eyes become dry and infected, and blindness may result. Because of numbness of the eye, the person cannot feel dirt or scratches in the eye.
Face - Damage to the internal lining of the nose causes scarring and eventual collapse of the nose.

Treatment available
The good news is that leprosy is curable. In 1981, the World Health Organization recommended the use of a combination of three antibiotics--dapsone, rifampin, and clofazimine--for treatment, which takes six months to a year or more.

During the course of treatment, the body may react to the dead bacteria with pain and swelling in the skin and nerves. This is treated with pain medication, prednisone, or thalidomide (under special conditions).

A hopeful outlook
Before treatment was available, a diagnosis of leprosy meant suffering and pain and being shunned by society. Today, antibiotics and good skin care will prevent the disease from destroying the body. Perhaps in the future a vaccine will eliminate this ancient scourge altogether.

Source: http://rarediseases.about.com/cs/infectiousdisease/a/071203.htm