Pathogenesis+-+Leishmaniasis

When an infected sandfly bites a human, the parasite that causes Leishmaniasis are released into the human host. The host's macrophages (or other phagocytic cells such as neutrophils in the blood stream) then ingest the parasite. The parasite then changes from its "original" form in the macrophage. Once this change occures, the parasite starts reproducing inside of the macrophage. It is then able to escape the macrophage and infect the host. When a sandfly bites an infected human, the sandfly ingests some of the human's infected macrophages. The parasite escapes the macrophage and then changes into its "original" form in the sandfly's gut. This form then reproduces and is ready to infect humans that the sandfly may bite.