This is a phase II/III open, comparative dose trial to find the lowest single dose of AmBisome for the treatment of primary, symptomatic visceral leishmaniasis(VL), in HIV negative patients. In this trial, the minimum effective dose will be determined in a sequential step, dose escalation design, which minimises the number of patients exposed to low, potentially inadequate doses and provides contemporaneous comparative data against the manufacturer's recommended dose schedule in this indication.