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Cryptosporidiosis, also known as crypto,〔(【引用サイトリンク】publisher=Centers for Disease Control and Prevention )〕 is a parasitic disease caused by ''Cryptosporidium'', a protozoan parasite in the phylum Apicomplexa. It affects the intestines and is typically an acute short-term infection. It is spread through the fecal-oral route, often through contaminated water;〔 the main symptom is self-limiting diarrhea in people with intact immune systems. In immunocompromised individuals, such as AIDS patients, the symptoms are particularly severe and often fatal. ''Cryptosporidium'' is the organism most commonly isolated in HIV-positive patients presenting with diarrhea. Treatment is symptomatic, with fluid rehydration, electrolyte correction and management of any pain. Despite not being identified until 1976, it is one of the most common waterborne diseases and is found worldwide. The parasite is transmitted by environmentally hardy microbial cysts (oocysts) that, once ingested, exist in the small intestine and result in an infection of intestinal epithelial tissue. ==Signs and symptoms== Symptoms appear from two to ten days after infection, with an average of 7 days,〔 and last for up to two weeks, or in some cases, up to one month.〔 There are 3 possible forms of the illness in immunocompetent people. The disease can be tragic or cause acute diarrhea or persistent diarrhea that can last for a few weeks. Diarrhea is usually watery with mucus. It is very rare to find blood or leukocytes in the diarrhea. As well as watery diarrhea, there is often stomach pains or cramps and a low fever. Other symptoms include nausea, vomiting, malabsorption and dehydration. Asymptomatic individuals (those with no symptoms) are nevertheless infective, and thus can pass on the infection to others. Even after symptoms have finally subsided, an individual is still infective for some weeks. Severe diseases, including pancreatitis, can occur. Immunocompromised people, cancer patients on chemotherapy, as well as very young or very old people, can develop a more severe form of cryptosporidiosis. There are 4 clinical presentations for patients with AIDS. 4% have no symptoms, 29% have a transient infection, 60% have chronic diarrhea, and 8% have a severe, cholera-like infection. With transient infections diarrhea ends within 2 months and Cryptosporidium is no longer found in the feces. Chronic diarrhea is diarrhea that lasts for 2 or more months. The most severe form results in the patients excreting at least 2 liters of watery diarrhea per day.〔 They can lose up to 25 liters per day. AIDS patients can have up to 10 stools per day. They experience severe malabsorption and can have 10% weight loss. Many of them never completely eliminate ''Cryptosporidium'' from their bodies. When ''Cryptosporidium'' spreads beyond the intestine, as it can predominantly in patients with AIDS, it can reach the lungs, middle ear, pancreas, and stomach. Thus, one symptom is pain in the right upper quadrant.〔 The parasite can infect the biliary tract, causing biliary cryptosporidiosis. This can result in cholecystitis and cholangitis.〔 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「Cryptosporidiosis」の詳細全文を読む スポンサード リンク
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