Leishmania donovani.

Amastigotes of Leishmania are spherical to ovoid and measure 1-5 µm long by 1-2 µm wide.  They possess a large nucleus, a prominent kinetoplast, and a short axoneme, the last of which is rarely visible by light microscopy.  The organisms reside in macrophages of the host and can be found throughout the body.

A	B

A:  Leishmania spp. amastigotes in a Giemsa-stained tissue scraping.
B:  Leishmania (Viannia) panamensis amastigotes in a Giemsa-stained tissue scraping.  Identification to the species level is not possible based on morphology and other diagnostic techniques such isoenzyme assay or PCR are needed.

C	D

C, D:  Leishmania (Viannia) panamensis amastigotes in a Giemsa-stained tissue scraping.

Amastigotes of Leishmania are spherical to ovoid and measure 1-5 µm long by 1-2 µm wide.  They possess a large nucleus, a prominent kinetoplast, and a short axoneme, the last of which is rarely visible by light microscopy.  The organisms reside in macrophages of the host and can be found throughout the body.

A	B

A, B:  Leishmania spp. amastigotes; touch-prep stained with Giemsa.

A	B

A, B:  Leishmania tropica amastigotes from an impression smear of a biopsy specimen from a skin lesion.  In Figure A, an intact macrophage is practically filled with amastigotes (arrows), several of which have a clearly visible nucleus and kinetoplast; in Figure B, amastigotes are being freed from a rupturing macrophage.  Patient had traveled to Egypt, Africa, and the Middle East.  Based on culture in NNN medium, followed by isoenzyme analysis, the species was identified as L. tropica.

Amastigotes of Leishmania are spherical to ovoid and measure 1-5 µm long by 1-2 µm wide.  They possess a large nucleus, a prominent kinetoplast, and a short axoneme, the last of which is rarely visible by light microscopy.  The organisms reside in macrophages of the host and can be found throughout the body.

A

A:  Amastigotes of Leishmania sp. in a biopsy specimen from a skin lesion, stained with hematoxylin and eosin (H&E).

B

B:  Leishmania mexicana in a biopsy specimen from a skin lesion stained with H&E.  The amastigotes are lining the walls of two vacuoles, a typical arrangement.  The species identification was derived from culture followed by isoenzyme analysis.

Promastigotes are not found in human tissue; this stage occurs in the mid-gut of the sand fly (genera Phlebotomus and Lutzomyia) intermediate hosts.  Promastigotes are elongate, slender and measure about 10-12 µm in length.  They have a large central nucleus and a kinetoplast located near the anterior end.  A flagellum arises at the anterior end, that may be longer than the rest of the promastigote.

A

A:  Leishmania sp. promastigotes from culture.