This book discusses the current public health challenges in leprosy control face, exploring opportunities that may potentially accelerate progress towards the elimination of leprosy. Leprosy is the least contagious of infectious diseases; it is caused by M. leprae and M. lepromatosis and mainly affects the skin and peripheral nerves. In addition to existing interest due to the variation in the clinical characteristics of the disease between people, the immune response in this pathology will also differ. In the course of the disease, leprosy patients can experience episodes of acute inflammatory reactions known as leprosy reactions. Leprosy reactions are complications that may occur before, during, or after treatment, and cause further neurological damages that can cause chronic disabilities. As such, the authors discuss the role of immune response in leprosy pathogenesis and leprosy reactions. The treatment of leprosy is always based on the final clinical and laboratory confirmation of the diagnosis. The diagnosed patient must be treated for 6 months in case of paucibacillary and 12 months in case of multibacillary. Further, precaution should be always taken to treat a confirmed disease, as many diseases mimic leprosy. In closing, the authors highlight the current evidence about the association of vitamin D and VDR to leprosy disease progression. This knowledge will help in developing new strategies for the treatment and clinical management of leprosy patients.