Giardiasis: clinical and therapeutic aspects.

Malabsorption was present in 29 of 40 symptomatic patients with giardiasis. Twenty-three had impaired D-xylose absorption; in 20 vitamin B12 absorption was low, and 15 patients had steatorrhoea. More severe malabsorption was associated with more marked histological abnormalities. Metronidazole, 2-0 g as a single daily dose on three successive days, produced a parasitological cure rate of 91%. In contrast, the standard course of mepacrine, 100 mg thrice daily for 10 days, eradicated the parasite in only 63% of patients. Improvements in absorption and jejunal morphology followed anti-giardial treatment. Tetracycline in eight patients failed to eradicate the parasite, intestinal absorption was unaltered, and histological appearances of the jejunal mucosa often deteriorated.