Giardia lamblia is one of the most prevalent intestinal protozoan of the human. G. lamblia is a flagellated parasitic which it transmits via fecal-oral route through direct or indirect ingestion of infectious cysts, causing giardiasis. Giardiasis has a global distribution and it is common in both children and adults. The prevalence of Giardia infection is higher in developing countries. Giardia protozoa are a common contaminant of freshwater, including many lakes and streams.