绦虫-科普123

绦虫

杂烩百科2023-02-02 15:54:02百科

绦虫(tapeworm)

扁形动物门绦虫纲一种身体两侧对称的寄生性扁虫，约3,000种，呈世界性分布。体长从约1公厘到15公尺余。头节上有吸盘，通常还有钩，用於固着在宿主的肝和消化道内。一旦固着成功，就通过其表皮吸收食物。整个躯体大体分为数段：头或头节，上有吸盘和钩；不分段的颈；以及一列形状相同的节片（具备雌雄生殖器官的身体部件）。节片由颈底部的一个生长区连续生成。受精後内含数千个胚体的成熟节片爆裂，随宿主粪便排出。整个生命周期可能需要不止一个宿主，但一般说来会与旋毛虫的生命周期十分相像。多种以人为宿主的绦虫属於带绦虫类；其中间宿主则可从其学名中辨识（如牛带绦虫是以牛为中间宿主）。在美国东南部，人被绦虫寄生的现象颇为常见；人被绦虫感染的途径主要是接触了受到污染的土壤或水，以及食用了烹煮不充分的肉和鱼。

English version：

tapeworm

Any of about 3,000 species (class Cestoda, phylum Platyhelminthes) of bilaterally symmetrical parasitic flatworms found worldwide. Tapeworms range from 0.04 in. (1 mm) to more than 50 ft (15 m) long. The head bears suckers and often hooks for attaching to the liver or digestive tract of the host. Once attached, tapeworms absorb food through their body wall. The body is often divided into a head or scolex possessing the suckers and hooks, an unsegmented neck, and a series of proglottids (units containing both male and female reproductive organs) which continually form in a growth region at the base of the neck. Following fertilization, each mature proglottid containing thousands of embryos breaks off and is eliminated in the host's feces. The life cycle may require more than one host but otherwise somewhat resembles that of the roundworm trichina. Many species that infest humans belong to the genus Taenia; the intermediate host is implied by the name (e.g., beef tapeworm, T. saginata). Human infestation is common in the southeastern U.S.; humans usually acquire tapeworms through fecal contamination of soil or water or inadequate cooking of meat or fish.