Diagnostic Parasitology

 Giardia lamblia
Giardia lamblia is the most common intestinal parasite identified in the U.S. The cysts, shown at right, are oval measuring from 11 to 14 µm in length and 7 to 10 µm in width. Four nuclei are usually visible along with axonemes, and median bodies. Often, the cyst will appear shrunken, pulling away from the cyst wall.
The trophozoites are described as having a 'tear-drop' shape and are 10 to 20 µm long and 5 to 10 µm wide. The trophozoites contain two nuclei, four pair of flagella, two axonemes, and two curved bodies called the median bodies. The image at left is from an iodine-stained wet-mount (1000x).
The image at right is a wet mount of a trophozoite viewed by phase-contrast microscopy. Image courtesy of Gustavo Gini.

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Copyright 2008 Don Lehman