【摘要】 <正> 一、前言 双腔科某些吸虫是对牛、羊、猪、骆驼等家畜危害严重的一类寄生虫,例如寄生在胰脏的各种阔盘吸虫(Eurytrema Looss,1907)及寄生在肝脏的矛形双腔吸虫(Dicrocoelium lanceatum Stiles et Hassall,1896)。前者分布全国各地,许多牛、羊群因此寄生虫病而大批死亡;后者主要分布在我国从东北到西北的各牧区中,在羊肝脏中寄生的虫体数量是以千、万来计算,严重地影响畜牧业生产。阔盘吸虫像矛形双腔吸虫一样,不仅是牲畜的重要寄生虫病的病原,而且也都能感染人体致病(图版Ⅰ图1),国内外病例常见不鲜(张月更多还原

【Abstract】 The present article reports on the biology and epidemiology of Eurytrema,coolo-maticum and E.pancrcaticum in China.The studies have been undertaken for many years in Fu-jian,South China,for E.coelomaticum in cattle,while special invcstiga-teins were conducted in Shuang-liao steppes in Western Ji-lin Province bordering Meng-gu,where E-pancrcaticum is highly endemic.The incidence of infection for E.coelomaticum in dairy cows is 62.20-72.22% and in ordinary cattle used for tilling the land in several People’s Communes in the vicinity of Fu-zhou is 14.22-45.50%.The incidence of infection in sheep in Shunng-liao steppes is 16-73% (average 51.07%).In Shuang-liao steppes it was found that the molluscan intermediate hosts for E.pancrcaticum belong to the land-snail of the genus Gancsclla Blanford,1863 (Family Pleurodontidae).They were tentatively assigned to species,Ganesella ste-arnsii Pilsbry,G.japonica (Pfeiffer) and G.myomphala (V.Martens).In Fu-zhou and other localities along the coast of Fu-jian epidemiologic studies were made for E.coelomaticum,the intermediate hosts of which,Bradybaena similaris Ferrusae and Cathaica ravida sieboldtiana Pfeiffer,were examined in successive years with the incidence of infection,0.54-7.96% (.average 3.52%) for the former and 0.08-7.41% (average 0.23%,) for the latter species.The second intermediate host of E.coelomaticum in Fu-zhou was found to be the meadow grasshopper,Conocephalus miculatus Le Guillou,first discovered by Basch (1965) in Malaysia.On the grassy hillside surrounding a dairy-farm outside the north gate of Fu-xluu city 314 of this Tettigoniid grasshoppers were examined with 21 positives (6.68%).Cysts contained in the haemocoel of each grasshopper were counted,the smallest number being 23 and the largest 1444.The seasonal infecton rates for both molluscan and insect intermediaries have been investigated the whole year round with the result that both intermediate hosts show high incidence of infection in the summer time and reach their peak in the fall-(July to September),and drops down in winter months.Experiments were conducted to feed mature daughter sporocysts of E.coelomaticum to several species of Tettigoniid grasshoppers,namely Conocephalus maculatiis Le Guillou,Xiphidiopsis suzukii Matsumura,Ducetio japonica Thub.,Hemacentrus unicolor Serv.,Euconocephalus varius (Walk).Subsequent dissections revealed three of them infected.They are C.maculatus,Xiphidiopsis suzukii and Euconocephalus varius.The last two allow us to record new experimental insect hosts for E.coelo- malicum.Further inquiries were made on the development of E.coelomaticum It was observed that the miracidimn hatches in the lumen of digestive gut of Bradybacna similaris,penetrates through its intestinal wall and comes to lie in the peri-intestinal connective tissue as an oval mother sporocyst with two excretory vesicles and a few germinal cells.The growing mother generation first shows internal partitions and later becomes irregularly lobed.As it matures and disintegrates the daughter sporocysts inside disperse and migrate to the respiratory chamber of the snail host.The entire molluscan phase of development takes about 6 months to one year before the emergence of mature daughter sporocysts and cereariae.The snails,which are infected in the spring begin to expel daughter sporoeysts in the autumn,while those infected in the fall do not shed sporocysts until the summer of next year.After being expelled from the mollusean host,the daughter sporocysts by their rhythmic contraction of both outer and inner cyst-walls transform into cystic structures with tail-like filaments on both ends.They are thus protected from desiccation and opportunities are afforded to be eaten by meadow grasshoppers.The cereariae then penetrate into the hacmoeoel of the insect and begin to form biconcave metacercarial cysts.At first the cysts are small and thin-walled.Gradually they become larger and the walls thicker.During the fall season when the room temperature declines to 26° to 32℃.,it takes about 20-25 days for the cysts to becom更多还原