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Leishmania parasites as the causative agent of leishmaniasis belong to Trypanosomatidae family. Parasite, vector, vertebrate host and environment are major factors in pathogenesis of Leishmania. 
Parasite dependent factors are virulence factors which exist in Leishmania species such as LPG, GP63. In recent years, the importance of these factors in the field of vaccine and drug has been considered by researchers. Sand fly biting behavior and salivary gland proteins are vector dependent factors which are effective in the Leishmania pathogenesis. Age, gender, nutrition, immune system, infectious diseases, genetic, occupation, socio-economic characteristics, and habitat are vertebrate host mediated factors. Temperature, rainfall, wind and its speed, soil, and continuous changes in climate are also environmental factors. Therefore the aim of this study was to evaluate the pathogenesis of Leishmania parasites.