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Ascariasis is a disease caused by the parasitic roundworm ''Ascaris lumbricoides''.〔 Infections have no symptoms in more than 85% of cases, especially if the number of worms is small. Symptoms increase with the number of worms present and may include shortness of breath and fever in the beginning of the disease.〔 These may be followed by symptoms of abdominal swelling, abdominal pain and diarrhea.〔 Children are most commonly affected, and in this age group the infection may also cause poor weight gain, malnutrition and learning problems.〔〔〔(【引用サイトリンク】url=http://www.who.int/mediacentre/factsheets/fs366/en/ )〕 Infection occurs by eating food or drink contaminated with ''Ascaris'' eggs from feces.〔 The eggs hatch in the intestines, burrow through the gut wall, and migrate to the lungs via the blood.〔 There they break into the alveoli and pass up the trachea, where they are coughed up and swallowed.〔 The larvae then pass through the stomach for a second time into the intestine where they become adult worms.〔 Ascariasis is classified as a neglected tropical disease as it is a type of soil-transmitted helminthiasis. These diseases are in turn part of a group of diseases called helminthiasis. Prevention is by improved sanitation, which includes improving access to toilets and proper disposal of feces.〔 Handwashing with soap appears protective. In areas where more than 20% of the population is affected, treating everyone at regular intervals is recommended.〔 Reoccurring infections are common.〔 There is no vaccine.〔 Treatments recommended by the World Health Organization are the medications albendazole, mebendazole, levamisole or pyrantel pamoate. Other effective agents include tribendimidine and nitazoxanide.〔 About 0.8 to 1.2 billion people globally have ascariasis with the most heavily affected populations being in sub-Saharan Africa, Latin America, and Asia.〔〔 This makes ascariasis the most common form of soil-transmitted helminthiasis. As of 2010 it caused about 2,700 deaths down from 3,400 in 1990. Another type of ''Ascaris'' infects pigs.〔 == Signs and symptoms == Most people who are infected with only a small number of worms have no symptoms. It is common to find that most people are infected by a small number of worms, while a small number of people are heavily infected, something that is characteristic of many worm infections.〔〔 Clinical features depend on the affected body site. 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「Ascariasis」の詳細全文を読む スポンサード リンク
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