Mycobacterium leprae causes leprosy, a chronic infectious disease. It has an impact on the peripheral nerves and the skin. It has no impact on the spinal cord or the brain. Leprosy is the most complicated and persistent of all human bacterial infections, with an average incubation time of 5-7 years. The disease can either be pauci- or poly-symptomatic. Pauci-symptomatic patients have nerve damage but no visible lesions on the skin, while poly-symptomatic patients have both nerve damage and visible skin lesions. Leprosy affects the immune system, causing people to become susceptible to other infections. It can also cause disabilities by damaging nerves in the skin and eyes. Although the disease cannot spread through the air, it can be transmitted from person to person via close contact with infected skin or mucous membranes. The only way to prevent leprosy is by avoiding exposure to M. leprae. There is no vaccine available for leprosy; however, multidrug therapy (MDT) can help control the disease if it is detected early. People with lepromatous leprosy, which is highly contagious, should not be housed with healthy individuals. Those who are diagnosed with dimorphic leprosy, which includes tuberculoid leprosy and indeterminate leprosy, can be treated with antibiotics and their health should not be put at risk by being housed with healthy individuals.