To be infected, one must come in contact with someone with the infectious form of the disease, and have some defect in one's immune system. There are three types of Hansen's disease of which a person can have either or a combination. The eye is sometimes affected which can lead to blindness. The tuberculoid type is the least serious, but has no association with tuberculosis. The tuberculoid is called that because under the microscope, the pathology looks like tuberculosis.
Lesions never appear in the lung.
They are found in the skin and nerves. The third type is borderline and it is a combination of the lepromatous and tuberculoid types. The warmer areas are usually spared. This means that the body absorbs bone and cartilage that is in the nose, hands and feet, causing them to shrink to a small size. In the hands, the severe bone absorption is called mitten hands.