Hesi medi surg Giardiasis

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What is Giardiasis? Giardiasis is a major diarrheal disease found throughout the world.  The flagellate protozoan Giardia intestinalis (previously known as G. lamblia or G. duodenalis), its caus... ative agent, is the most commonly identified intestinal parasite in the United States and the most common protozoal intestinal parasite isolated worldwide. Giardiasis usually represents a zoonosis with cross-infectivity between animals and humans.  G. intestinalis can cause asymptomatic colonization or acute or chronic diarrheal illness. The organism has been found in as many as 80% of raw water supplies from lakes, streams, and ponds and in as many as 15% of filtered water samples. Pathophysiology Infection with Giardia intestinalis most often results from fecal-oral transmission or ingestion of contaminated water. Person-to-person spread is common, with 25% of family members with infected children themselves becoming infected. Giardia has one of the simplest life cycles of all human parasites; the life cycle is composed of 2 stages: (1) the trophozoite, which exists freely in the human small intestine; and (2) the cyst, which is passed into the environment. Upon ingestion of the cyst (see the second image below), contained in contaminated water or food, excystation occurs in the stomach and the duodenum in the presence of acid and pancreatic enzymes. The trophozoites pass into the small bowel where they multiply rapidly, with a doubling time of 9-12 hours; as trophozoites pass into the large bowel, encystation occurs in the [Show More]

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