IL10 and infection: The outcome of the typical symptomatic VL is influenced by the immune response developed by the host wherein the systemic infection, with the spread of the parasites to the spleen, liver, lymph nodes, bone marrow, and other organs are accompanied by a high titer of circulating antibodies, marked up-regulation of IL-4 and IL-10 [16–18]–and unresponsiveness to Type-1 T-cell mediated immunity.