Mycobacterium leprae. Colour transmission electron micrograph of a section through a group of Mycobacterium leprae bacteria, cause of leprosy. Also known as Hansen's disease. Each bacterium cut through appears rounded, but they are rod-shaped Gram-positive bacilli. The disease is spread in droplets of nasal mucus and a person is infectious only during the first stages of leprosy. The bacteria incubates for 3-5 years. Nerve damage usually occurs in limbs and facial areas, which may lead to skin damage, blindness, and disfigure- ment. Drug treatment kills the bacteria, but surgery may be required. Vaccines are being tested. Magnification: x118,000 at 6x7cm size. x350,000 at 8x10 inch size.