Skin

"The skin is the largest organ of the body, with a total area of about 20 square feet. The skin protects us from microbes and the elements, helps regulate body temperature, and permits the sensations of touch, heat, and cold.
Skin has three layers: The epidermis, the outermost layer of skin, provides a waterproof barrier and creates our skin tone.
The dermis, beneath the epidermis, contains tough connective tissue, hair follicles, and sweat glands.
The deeper subcutaneous tissue (hypodermis) is made of fat and connective tissue.
The skin’s color is created by special cells called melanocytes, which produce the pigment melanin. Melanocytes are located in the epidermis."

Leprosy

Leprosy is a disease that has been known since biblical times. It causes skin sores, nerve damage, and muscle weakness that gets worse over time. Leprosy is caused by the bacterium Mycobacterium leprae. It is not very contagious and it has a long incubation period (time before symptoms appear), which makes it hard to know where or when someone caught the disease. Children are more likely than adults to get the disease.