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Visceral leishmaniases (VL) or kala-azar is the most dreaded and devastating amongst the various forms of leishmaniases. The disease, though localized in certain areas only, has gained immense importance because of high mortality rate, mainly in children. The parasite is responsible for a spectrum of clinical syndromes, which can, in most extreme cases, go from an asymptomatic infection to a fatal form of VL. Chemotherapeutic measures, alone are not sufficient to control and contain the disease. As an alternate strategy, vaccination is also under experimental and clinical trails. The situation unquestionably demands the use of proper screening system, rationale chemical synthesis, vaccine development and targeted vaccine delivery. Thus, development of an acceptable vaccine is not an easy task. While the factors, which determine clinical outcomes, are in part, a feature of the parasite, it is the nature of the host and its genetic make up and immune status that play crucial role. The prerequisite of reliable animal model is that it should have a considerably good correlation with the clinical situation and is expected to mimic the pathological features and immunological responses observed in humans when exposed to a variety of Leishmania spp. with different pathogenic characteristics. Many experimental animal models like rodents, dogs and monkeys have been developed, each with specific features, but none accurately reproduces what happens in humans. In addition to the nature of the host, the major difference between natural and experimental infections is the parasite inoculum; in natural conditions, the infected sand fly vector deposits a …