Life Cycle
< Infection occurs when infected sandfly regurgitates infective promastigotes into the blood while feeding.

< The promatigotes are phagocytized by macrophages and transform into amastigotes.
< The amastigotes multiply by binary fission in the macrophages.
Microscopy of Leishmania species
< The life cycle is continued when a sandfly feeds on an infected person and ingests the amastigotes in the macrophages.


Infection with Leishmania species can result in 3 main types of disease depending on the species, geographic region and host immune response.

Leishmania donovani produces visceral leishmaniasis (kala-azar).  Symptoms include fever (often 2 fever spikes per day), enlargement of the spleen and liver, weakness, and progressive emaciation.  The disease is often fatal without treatment, but survivors often develop immunity. 

Leishmania tropica and  L. mexicana produce cutaneous leishmaniasis which is characterized by skin lesions (oriental sore).  Infected macrophages containing amastigotes are found primarily at the site of infection around the sores.  The sores are chracterized by an elevated rim encircling the lesion.  The sores generally heal by themselves within a year, but secondary bacterial infections are possible in open sores.

Leishmania braziliensis produces mucocutaneous leishmaniasis, characterized by lesions near mucosal membranes.  The intitial site if infection is a small red papule that ulcerates in a few weeks.  The lesions are flat (no raised rim) and often oozing.  Infections of the ear, nose and mouth area lead to degeneration of the cartilage and soft tissues, resulting in disfigurement.

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