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Giardiasis (popularly known as beaver fever) is a zoonotic parasitic disease caused by the flagellate protozoan ''Giardia lamblia'' (also sometimes called ''Giardia intestinalis'' and ''Giardia duodenalis''). The giardia organism inhabits the digestive tract of a wide variety of domestic and wild animal species, as well as humans. It is the most common pathogenic parasitic infection in humans worldwide; in 2013, there were about 280 million people worldwide with symptomatic giardiasis.〔 ==Signs and symptoms== Symptoms include weakness in the body, loss of appetite, diarrhea, loose or watery stools, stomach cramps, upset stomach, projectile vomiting (uncommon), bloating, excessive gas, and burping (often sulfurous). Symptoms typically develop 9–15 days after exposure,〔 but may occur as early as one day. Symptoms are caused by Giardia organisms infecting the cells of the duodenum and jejunum of the small intestine〔 and blocking nutrient absorption. Most people are asymptomatic; only about a third of infected people exhibit symptoms. If the infection is not treated, these symptoms may last for six weeks or more. Symptomatic infections are well recognized as causing lactose intolerance, which, while usually temporary, may become permanent. Although hydrogen breath tests indicate poorer rates of carbohydrate absorption in those asymptomatically infected, such tests are not diagnostic of infection. It has been suggested that these observations are explained by symptomatic giardia infection allowing for the overgrowth of other bacteria.〔 Some studies have shown giardiasis should be considered as a cause of vitamin B12 deficiency as a result of the problems caused within the intestinal absorption system. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Giardiasis」の詳細全文を読む スポンサード リンク
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