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Giardiasis

life science Maturity 11-13 Next article →

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"text": "Giardiasis is a widespread parasitic disease caused by a microscopic organism called Giardia duodenalis. This protist is a major human pathogen found in many parts of the world. In developed nations, infection rates can reach 7%. In developing countries, these rates are much higher, sometimes hitting 30%. In 2013 alone, approximately 280 million people worldwide suffered from symptomatic cases. Because of its high prevalence and impact, the World Health Organization classifies it as a neglected disease.

US giardiasis incidence 2005
US giardiasis incidence 2005

\n\nThe life cycle of Giardia duodenalis consists of two distinct forms. The first is the cyst, which is a hardy, protective stage. These cysts are highly infectious and can survive in cold water for nearly three months. When a person swallows these cysts, they undergo a process called excystation. They transform into the trophozoite form inside the host. Trophozoites are the active, moving stage of the parasite. They attach themselves to the intestinal wall to replicate within the gut. Eventually, they convert back into cysts to be excreted in feces.

\n\nUnderstanding the mechanism of infection requires looking at the small intestine. Once trophozoites attach to the intestinal lining, they cause significant physical changes. They cause villous flattening, which means the tiny, finger-like projections in the gut become flat. This process inhibits brush border enzymes, which are necessary to break down sugars. The parasite also triggers programmed cell death, also known as apoptosis, in intestinal cells. This damage increases intestinal permeability, allowing substances to leak through the barrier. As a result, the body suffers from malabsorption, meaning it cannot properly take in nutrients and water.\n\nSymptoms of giardiasis vary greatly among different people. Some individuals are asymptomatic, meaning they show no signs of illness even if the parasite remains. Others experience severe gastrointestinal distress. A prominent symptom is steatorrhea, a type of diarrhea characterized by fatty, greasy, and foul-smelling stools that often float. This occurs because the body cannot absorb fats correctly. Other common symptoms include abdominal cramps, gas, nausea, and vomiting. In some cases, people may experience skin rashes, hives, or joint swelling. Fever is less common, occurring in only about 15% of cases.

Histopathology of Giardia lamblia in duodenum
Histopathology of Giardia lamblia in duodenum

\n\nLong-term infection can lead to serious nutritional issues. Malabsorption of vital nutrients like vitamin A, folate, and vitamin B12 is common

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File:Giardia LifeCycle.gif
Giardia LifeCycle.gif
File:Histopathology of Giardia lamblia in duodenum.png
Histopathology of Giardia lamblia in duodenum.png
File:US giardiasis incidence 2005.gif
US giardiasis incidence 2005.gif
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