Giardia – Flagellates
Giardia intestinalis inhabits the intestine of man. It has the distinction of being probably the first parasitic protozoan to be seen by Antony Van Leeuwenhoeck in 1681, in his own faeces. This is a very common parasite in human especially in children and can cause a disease giardiasis. The trophozoite is pear shaped.
Figure: Giardia intestinalis Cyst with two cells as often seen in faeces.
It has two nuclei between which lie 8 basal bodies giving rise to 8 flagellae by means of which the parasite can swim. Normally this protozoan lives in the small intestine but severe infestation cause diarrhoea and epigastric pain. The cysts are discharged in faeces and infection occurs via faeces contaminated drinking water.