Abstract: Visceral Leishmaniasis (Leash’ma NIGH a sis) is a vector- borne anthrozoonotic disease caused by obligate intracellular macrophage protozoan Leishmanian donovani belongs to genus within the family Trypanosomatidae. This is very serious disease and endemic in warmer part of the world covering almost 88 countries (16 developed and 72 developing or 66 countries in the Old World while 22 countries located in the New World). A total of 350 million people at risk and 12 million cases of infection every year. Out of 500, 000 cases of Visceral Leishmaniasis, more than 90 percent are reported from India, Bangladesh, Southern Sudan, Nepal and Northeast Brazil. The protozoan parasite Leishmania exists at least in two alternative forms in two different hosts, 1. Amastigote form 2. Promastigote form Promastigotes of Leishmania (infective stage in human) are released in human blood by female sand fly (Phelobotomus argentipes). After entering, these parasites are engulfed by the macrophages of the patients for killing them but due to several protective mechanisms leishmanian promastigotes are not only protected himself inside the macrophages but also rapidly divide within it and releases about ~20 amastigotes form each infected macrophages by bursting them.