Pathophysiology
Promastigotes of leishmania are transmitted to human skin by the bite of a sandfly. Leishmania then invades human macrophages and replicates intracellularly.
A raised, red lesion develops at the site of the bite (often weeks or sometimes years afterwards). The lesion then ulcerates and may become secondarily infected with bacteria. In many species (for example, L. major) the lesion often spontaneously heals with atrophic scarring. In some species (for example, L. viannia braziliensis) the lesion may spontaneously heal with scarring, but then re-appear elsewhere (especially as destructive mucocutaneous lesions). Lesions of other leishmania species may spontaneously heal and then re-appear as satellite lesions around the site of the original lesion, or along the route of lymphatic drainage.
Some species tend to cause cutaneous leishmaniasis (e.g., L. major and L.tropica), whereas some species tend to cause visceral leishmaniasis (e.g., L. infantum and L donovani), though emerging research (due to high deployment rates of western countries to indigenous areas) is showing these species specific presentation lines are blurring.
Read more about this topic: Cutaneous Leishmaniasis