An intestinal infection caused by a giardia parasite. Giardiasis can be transmitted from person to person or by contaminated food or water. It most frequently occurs in places with inadequate sanitation and contaminated water.
Humans have coexisted with parasites for hundreds of thousands of years, and many diseases result from parasitic infections ranging from asymptomatic presentation in some intestinal parasites to fatal fever and anemia in malaria.
Diarrhea is one of the most common presentations of parasites, and a large number of worms can cause it if they infest the gastrointestinal system. Giardia is perhaps one of the most common of these parasites.