Electron microscopy in the diagnosis of giardiasis.

Biopsy specimens of intestinal mucosa from two patients with malabsorption syndrome were examined with routine light and electron microscopy. Both showed intact intestinal mucosa, but by electron microscopy, the presence of Giardia lamblia in the intervillar spaces was identified. Electron microscopy is useful for the identification of this parasite, since the stool examinations in up to 50% may be negative. The parasites appear in light microscopy as cellular debris and can be easily overlooked, while by electron microscopy the typical morphologic features of the parasite are diagnostic.