Giardia intestinalis is one of the most common intestinal protozoa in humans.This parasite, which has a cosmopolitan distribution, poses a significant public health problem, particularly in countries with poor socioeconomic conditions and sanitation.It is known to be one of the main causes of waterborne diarrhea outbreaks. The parasite’s life cycle consists of two stages: The trophozoitestage is the form responsible for the clinical symptoms of the disease and is activelypresent in the intestine. The cyst stage is resistant to the external environment and is the form responsible for the transmission of the diseaseto different hosts. The disease can be transmitted to humansthrough food and water contaminated with cysts, the infectious form of the parasiteor directly through the fecal-oral route. The most prominent clinical symptom is diarrhea; stools are typically greasy (steatorrhea), watery, and foul-smelling. Other symptoms include abdominal cramps, dehydration, nausea, vomiting, gas, bloating, weight loss, and growth retardation in children. These symptoms may vary depending on the clinical course of the disease. To prevent the spread of the disease in the community, basic protective measures include paying attention to personalhygiene and preventing sewage water from mixing with drinking or irrigation sources.