Diagnostic Findings [Last Modified: ]
Giardiasis
[Giardia intestinalis (syn. Giardia lamblia)]
Causal Agent Life Cycle Geographic Distribution Clinical Features Laboratory Diagnosis Treatment

Microscopy

Giardia intestinalis trophozoite, trichrome Giardia intestinalis trophozoite, iron hematoxylin Giardia intestinalis trophozoite, iron hematoxylin
A B C

A, B, C: Three trophozoites of Giardia intestinalis, stained with trichrome, (A), and stained with iron hematoxylin (B and C).  Each cell has two nuclei with a large, central karyosome.  Cell size: 9 to 21 µm in length.

Giardia intestinalis trophozoites in culture
D

D: Giardia intestinalis in culture.  In these preparations, the flagellae (four pairs per cell) are clearly visible.

Giardia intestinalis cyst, iron hematoxylin Giardia intestinalis cysts, iron hematoxylin Giardia intestinalis cyst, wet mount
E F G

E, F, G: Cysts of Giardia intestinalis, stained with iron hematoxylin (E, F) and in a wet mount (G, from a patient seen in Haiti).  Size: 8 to 12 µm in length.  These cysts have two nuclei each (more mature ones will have four).

Cysts of Giardia intestinalis and oocysts of C. parvum
H

H: Cysts of Giardia intestinalis (lower right) and oocysts of C. parvum (upper left) labeled with commercially available immunofluorescent antibodies.
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