Giardia is an enteric protozoan pathogen, which infects humans, domestic animals and wildlife worldwide. The giardiasis is an infectious disease caused by Giardia intestinalis, waterborne transmission and has a common link with poverty. Travelers are at risk to be infected with giardiasis when they visit poor countries and consume non potable water. Our current state of knowledge of Giardia is summarized here and a list of some effective control measures is enumerated.Giardiasis como causa de Diarrea