Specialized surface adaptations of Giardia lamblia.

Although Giardia lamblia trophozoites were first described by Von Leeuwenhoek in his own diarrheic stool, relatively little is known of the basic biology of this common parasite or the pathophysiology of giardiasis. In particular, there is little specific information about trophozoite properties that cause diarrhea, as neither toxins nor conventional virulence factors have been identified. Therefore, parasite adaptations that promote cyst survival in the external environment and infection and trophozoite persistence in the small intestine, may be viewed as key virulence properties. This review focuses on unusual surface structures of the trophozoite and cyst forms that enable Giardia to be such a successful parasite.