Abstract:

Objective To study the in vitro effect of dihydroartemisinin （DHA） on Giardia lamblia. Methods Trophozoites of G. lamblia were cultivated with modified TYI-S-33 medium that contains dihydroartemisinin （DHA）. The trophozoites were morphologically observed respectively with light and electron microscopes after treated with the drug. Results The mortality increased with the prolongation of the time of the drug action and the increase of drug concentration（P<0.01）. While at the same concentration of 100 μg/ml, the mortality increased from 46.6% for 12 h to 100% for 24 h（P<0.05）. For 12 h, the mortality of G. lamblia was from 46.6% at concentration of 100 μg/ml to 100% at 200μg/ml. Under optical microscope, deformation and swelling of the parasites were observed when treated with DHA for 12、24 and 48 h. Movement of the flagella became slow or stopped. Under electron microscope, the trophozoites were swollen and deformed, vacuoles were seen in the cytoplasm, and the cell membrane ruptured and fell off. The cytoplasm protrusions appeared on the surface of the plasma membrane. The adhesive disc changed into large bubbles and the perinuclear space became wider and the deformed nucleus was seen. Conclusion DHA shows a strong impairment on the plasma membrane and cytoskeleton of Giardia lamblia.

Key words: Giardia lamblia, Dihydroartemisinin, Injuries