saginata causing intestinal taeniasis), most highly developed form of the parasite(e.g Trypanosoma cruci causing African sleeping sickness) or where the parasite replicates sexually(e. g, Paragonimus westermani) are called the definitive hosts. The definitive hosts may be human or non-human living things 2) Intermediate host(中间终主) The hosts which harbour the larval stages of parasite development or the asexual forms of the parasite are called intermediate host. Some times two different hosts may be required to complete different larval stages. These are known as the first and second intermediate hosts respectively(e. g snails t] are the first intermediate hosts and fresh water fish are the second intermediate hosts for Clonorchis sinensi AfRs s 3) Reservoir host(保虫宿主) The animal which harbours the parasites and serves as an important source of infection to other susceptible hosts are known as reservoir host(e.g,water buffalo is the reservoir host for schistosomiasis血吸虫病) 4) Paratenic host or transport host(转续宿主) The larva of some parasites can invade a non-normal host, but can not develop, and only keep the larva stage. If the larva enter a normal definitive host, it can continue to develop into adult worm. The non-normal host is called paratenic lost or transport host. It functions as a transport or carrier host TAXONOMY(分类学) ature(命名法) Nature”1758), each parasite has two names: a Genus(属名) and a Species name(种名). These names are derived either from (1)Greek or Lati n wor (2) Names of their discoverers (3) Geographical area where found (4)Hosts in which parasites are found, or (5)Habitat of the parasite The correct scientific name of the parasite consists of the genus and species to which belong, the name of the designator and the year in which it was discovered(e.g, Angiostrongylus cantonensis管圆线虫Chen,1935) Dougherty,1946) The animal parasites of human and most vertebrates are contained in five or more major ubdivisions or phyla (IT) Phylum Sarcomastigophora(肉鞭毛虫门). This phylum is divided into two subphyla:the Mastigophora or flagellates(鞭毛虫纲), and the Sarcodina or amebae(肉足纲) Phylum Apicomplexa(JiAl]) Members of this phylum are tissue parasites. Apicomplexa have a complex life cycle with alternating sexual and asexual generations. Phylum Microspore(微孢子门) Members of the Microspora are minute intracellular parasites of many kinds of vertebrates and invertebrates, and they differ significantly in structure from the Apicomplexa. Microsporidia rarely cause diseases in immunocompetent persons, but many do so with greater frequency in immunosuppressed persons Phylum Ciliophora(纤毛虫纲) The ciliates include a variety of free- living and symbiotic species. The only ciliate parasite of human is Balantidium coli, found in the intestinal tract. Although rare, it is important, as it may produce severe intestinal symptoms Phylum Platyhelminthes(扁形动物门) The Platyhelminthes, or flatworms,are multicellular animals characterized by a flat bilaterally symmetric body. Most flatworms are4 saginata causing intestinal taeniasis), most highly developed form of the parasite(e.g., Trypanosoma cruzi causing African sleeping sickness) or where the parasite replicates sexually(e.g., Paragonimus westermani) are called the definitive hosts. The definitive hosts may be human or non-human living things. 2) Intermediate host（中间终主） The hosts which harbour the larval stages of parasite development or the asexual forms of the parasite are called intermediate host. Some times two different hosts may be required to complete different larval stages. These are known as the first and second intermediate hosts respectively(e.g., snails 钉螺 are the first intermediate hosts and fresh water fish are the second intermediate hosts for Clonorchis sinensi 肝吸虫 s). 3) Reservoir host（保虫宿主） The animal which harbours the parasites and serves as an important source of infection to other susceptible hosts are known as reservoir host(e.g., water buffalo is the reservoir host for schistosomiasis 血吸虫病). 4) Paratenic host or transport host（转续宿主） The larva of some parasites can invade a non-normal host, but can not develop, and only keep the larva stage. If the larva enter a normal definitive host, it can continue to develop into adult worm. The non-normal host is called paratenic host or transport host. It functions as a transport or carrier host. TAXONOMY（分类学） According to the biomial nomenclature（命名法） as suggested by Linnaeus(“Systema Nature” 1758),each parasite has two names: a Genus(属名) and a Species name（种名）. These names are derived either from ⑴ Greek or Latin words ⑵ Names of their discoverers ⑶ Geographical area where found ⑷ Hosts in which parasites are found, or ⑸ Habitat of the parasite The correct scientific name of the parasite consists of the genus and species to which it belong, the name of the designator and the year in which it was discovered(e.g., Angiostrongylus cantonensis 管圆线虫(Chen, 1935) Dougherty, 1946). The animal parasites of human and most vertebrates are contained in five or more major subdivisions or phyla（门）. Phylum Sarcomastigophora(肉鞭毛虫门). This phylum is divided into two subphyla: the Mastigophora or flagellates(鞭毛虫纲), and the Sarcodina or amebae（肉足纲）. Phylum Apicomplexa(顶复门) Members of this phylum are tissue parasites..Apicomplexa have a complex life cycle with alternating sexual and asexual generations. Phylum Microspora(微孢子门) Members of the Microspora are minute intracellular parasites of many kinds of vertebrates and invertebrates, and they differ significantly in structure from the Apicomplexa. Microsporidia rarely cause diseases in immunocompetent persons, but many do so with greater frequency in immunosuppressed persons. Phylum Ciliophora(纤毛虫纲) The ciliates include a variety of free-living and symbiotic species. The only ciliate parasite of human is Balantidium coli, found in the intestinal tract. Although rare, it is important, as it may produce severe intestinal symptoms. Phylum Platyhelminthes( 扁 形 动物 门) The Platyhelminthes, or flatworms, are multicellular animals characterized by a flat, bilaterally symmetric body. Most flatworms are