Leishmaniasis is a complex disease caused by Leishmania infection, producing variable clinical symptoms, e.g., cutaneous, mucocutaneous, and visceral leishmaniases [1–3]. Cutaneous leishmaniasis (CL) caused, for example, by Leishmania major/L. tropica is marked by the appearance of skin lesion in various forms, which are often innocuous and self-healing, while mucocutaneous leishmaniasis (MCL) caused, for example, by L. braziliensis is a protracted disease, resulting sometimes in facial disfigurement of the ear, mouth, and nose. Neither CL nor MCL is life-threatening per se. Only in non-healing case has death of these patients been reported due to secondary infections or other causes, e.g., suicide as a result of unbearable psychological stress. Visceral leishmaniasis (VL) caused by L. donovani/L. infantum is far more severe. It is often fatal, if untreated, resulting from systemic and progressive infection of macrophages by Leishmania in the reticuloendothelial systems or lymphoid organs, chiefly the spleen, liver, and bone marrow. Disorders of hematological and hepatosplenic functions are thus the clinical manifestations of VL, including hepatosplenomegaly, fever, anemia, leucopenia, hypergammaglobulinemia, and cachexia. The development of all leishmaniases follows a chronic course lasting for months and sometimes years.