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Lymphatic filariasis, also known as elephantiasis tropica, is caused by parasitic worms of the roundworm family. Many cases of the disease have no symptoms. Some people however, develop large amounts of swelling of the arms, legs, or genitals. The skin may also become thicker, and pain may occur. The changes to the body can cause social and economic problems for the affected person. The worms are spread by the bites of infected mosquitoes. Infections usually begin when people are children. Three types of worms can cause the disease: ''Wuchereria bancrofti'', ''Brugia malayi'', and ''Brugia timori''. ''Wuchereria bancrofti'' is the most common. The worms damage the lymphatic system.〔 The disease is diagnosed by looking, under a microscope, at blood collected during the night. The blood should be in the form of a thick smear and stained with Giemsa stain. Testing the blood for antibodies against the disease may also be used. Prevention is by treating, yearly, entire groups in which the disease exists, in an effort to get rid of the disease in that group. This takes about six years. Medications used include antiparasitics such as albendazole with ivermectin, or albendazole with diethylcarbamazine. The medications do not kill the adult worms but prevent further spread of the disease until the worms die on their own. Efforts to prevent mosquito bites are also recommended, including reducing the number of mosquitoes and promoting the use of bed nets.〔 More than 120 million people are infected with lymphatic filariasis and about 1.4 billion people are at risk of the disease in 73 countries. It is most common in Africa and Asia. The disease results in economic losses of many billions of dollars a year.〔 ==Signs and symptoms== The most spectacular symptom of lymphatic filariasis is elephantiasis— edema with thickening of the skin and underlying tissues; this was the first disease discovered to be transmitted by mosquito bites. Elephantiasis results when the parasites lodge in the lymphatic system. The skin condition the disease causes is called "elephantiasis tropica" (also known as "elephantiasis arabum"). Elephantiasis mainly affects the lower extremities; the ears, mucous membranes, and amputation stumps are affected less frequently. However, various species of filarial worms tend to affect different parts of the body: ''Wuchereria bancrofti'' can affect the arms, breasts, legs, scrotum, and vulva (causing hydrocele formation), while ''Brugia timori'' rarely affects the genitals. Those who develop the chronic stages of elephantiasis are usually amicrofilaraemic and often have adverse immunological reactions to the microfilariae as well as the adult worms. The subcutaneous worms present with skin rashes, urticarial papules, and arthritis, as well as hyper- and hypopigmentation macules. ''Onchocerca volvulus'' manifests itself in the eyes, causing "river blindness" (onchocerciasis), one of the leading causes of blindness in the world.〔 〕 Serous cavity filariasis presents with symptoms similar to subcutaneous filariasis, in addition to abdominal pain, because these worms are also deep-tissue dwellers. Elephantiasis leads to marked swelling of the lower half of the body. Image:Elephantitus.jpg|Drawn from the collection at the National Museum of Health and Medicine and shows the effect of elephantiasis in an historic context. Anatomical items: Left Leg, Scrotum. Image:Elephantiasis.jpg|Elephantiasis of the legs due to filariasis. Luzon, Philippines. File:Bundesarchiv Bild 105-DOA0229, Deutsch-Ostafrika, Einheimischer mit Elefantiasis.jpg|Man with massive scrotal elephantiasis, Tanzania, early 20th century 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「lymphatic filariasis」の詳細全文を読む スポンサード リンク
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