Alternative definition : KEGG: Leishmania is an intracellular protozoan parasite of macrophages that causes
visceral, mucosal, and cutaneous diseases. The parasite is transmitted to humans by
sandflies, where they survive and proliferate intracellularly by deactivating the
macrophage. Successful infection of Leishmania is achieved by alteration of signaling
events in the host cell, leading to enhanced production of the autoinhibitory molecules
like TGF-beta and decreased induction of cytokines such as IL12 for protective immunity.
Nitric oxide production is also inhibited. In addition, defective expression of major
histocompatibility complex (MHC) genes silences subsequent T cell activation mediated
by macrophages, resulting in abnormal immune responses.;