Page 457 - Review of Medical Microbiology and Immunology ( PDFDrive )

mebooksfree.com

mebooksfree.com
mebooksfree.com
mebooksfree.com
mebooksfree.com
mebooksfree.com
mebooksfree.com mebooksfree.com mebooksfree.com mebooksfree.com mebooksfree.com mebooksfree.com
446
PART VI Parasitology

mebooksfree.com mebooksfree.com mebooksfree.com mebooksfree.com mebooksfree.com mebooksfree.com

mebooksfree.com mebooksfree.com mebooksfree.com mebooksfree.com mebooksfree.com mebooksfree.com

FIGURE 52–13
Leishmania donovani. Life cycle. Right side of figure describes the stages within the human (blue arrows). Humans are
infected at step 1 when the sandfly bites human and injects promastigotes. Sandfly is infected at step 5 when it ingests macrophages contain-
ing amastigotes in human blood. Left side of figure describes the stages within the sandfly (red arrows). (Source: Dr. Alexander J. da Silva and Melanie
Moser, Centers for Disease Control and Prevention.) The infected cells die and release progeny amastigotes
mebooksfree.com mebooksfree.com mebooksfree.com that infect other macrophages and reticuloendothelial cells. mebooksfree.com
mebooksfree.com
mebooksfree.com

The cycle is completed when the fly ingests macrophages
containing the amastigotes.

Pathogenesis & Epidemiology
In visceral leishmaniasis, the organs of the reticuloendo-
thelial system (liver, spleen, and bone marrow) are the
most severely affected. Reduced bone marrow activity,
coupled with cellular destruction in the spleen, results in
anemia, leukopenia, and thrombocytopenia. This leads
mebooksfree.com
mebooksfree.com mebooksfree.com mebooksfree.com cells. The marked increase in IgG is neither specific nor mebooksfree.com
mebooksfree.com
to secondary infections and a tendency to bleed. The
striking enlargement of the spleen is due to a combina-
tion of proliferating macrophages and sequestered blood
FIGURE 52–14
Leishmania donovani—amastigotes. Arrow
protective.
points to an amastigote (nonflagellated form) in cytoplasm of bone
Kala-azar occurs in three distinct epidemiologic pat-
marrow cell. (Source: Dr. Francis Chandler, Public Health Image Library, Centers
terns. In one area, which includes the Mediterranean basin,
for Disease Control and Prevention.)

mebooksfree.com mebooksfree.com mebooksfree.com mebooksfree.com mebooksfree.com mebooksfree.com