螺类宿主感染钩棘单睾吸虫尾蚴的调查与感染实验

本文对钩棘单睾吸虫的第一中间螺蛳宿主自然感染情况进行调查，显示了一年中该虫尾蚴感染率随季节呈动态变化，10月份瘤拟黑螺感染率高达5.42％。各地瘤拟黑螺与纹沼螺平均感染率分别为2.45％（38／1548）与0.73％（20／2726），表明前者为本吸虫更为适宜的第一中间宿主。感染实验结果表明，该虫尾蚴侵染鱼类宿主后须经25d囊蚴发育完全成熟，而囊蚴感染终未宿主仅4d即可发育为成虫并产卵，其发育迅速为吸虫类所罕见。     

螺类宿主感染钩棘单疲睾吸虫尾蚴的调查与感染实验

本文对钩棘单睾吸虫的第一中间螺蛳宿主自然感染情况进行调查。显示了一种中该中尾蚴感染率随季节呈动态变化，１０月份交瘤拟黑螺感染率高达５．４２％。各地瘤专黑螺与纹沼螺平均感染率分别为２．４５％（３／１５４８）与０．７３％（２０／２７６５），表明前者为本吸虫更为适宜的第一间宿主。感染实验结果表明，该虫尾螺侵染鱼类宿主后须经２５ｄ囊蚴发育完全成熟，而囊螺感染终末缩主仅４ｄ即可发育成为虫并产卵，其发育迅速为     

日本棘隙吸虫尾蚴的生态学研究

通过对日本棘隙吸虫尾蚴生态学观察,结果表明尾蚴的发育、逸放、活动,感染鱼类宿主等均与温度、光度有密切关系。在水温27～32℃时,螺体内子雷蚴可不断增殖尾蚴,并有大量的尾蚴逸出;低于24℃,增殖能力减弱,尾蚴逸出明显减少;14℃时不再有尾蚴逸出。小型鱼种的日本棘隙吸虫囊蚴感染率和感染度之所以比大型鱼种者高,在于尾蚴具有明显的趋光性和好在水体浅层活动,与小型鱼种接触的机会较多之故。纹沼螺内尾蚴自然感染率以采于7～10月者为高,调查第一中间宿主应选择适宜的季节进行。     

藐小棘隙吸虫不经中间宿主完成囊蚴期发育的发现

本文观察了藐小棘隙虫尾蚴在天然及实验室条件下生长发育情况。结果显示该尾蚴不仅可在第二中间宿主淡水鱼的鱼鳃中发育成囊蚴,还能在英终宿主犬的胃液中以及生理盐水等实验条件下完成囊蚴期发育。这一发现解释了藐小棘隙吸虫尾蚴经口直接感染终宿主(人、犬、猫)的原因。     

铜锈环棱螺内叶形棘隙吸虫尾蚴实验感染观察

叶形棘隙吸虫(Echinochasmus perfoliatusRatz,1908)病系人畜共患的鱼源性寄生虫病。在日本与我国湖北汉川等地均有报道人体感染。其第一中间宿主为纹沼螺。我们在铜锈环棱螺(Bellamyaaeruginosa)内,发现一种具棘口科吸虫特征的尾蚴,通过动物感染实验,证明其为叶形棘隙吸虫。 材料与方法 铜锈环棱螺采自福建云霄县火田乡居民区附近的池塘内。除去螺体外壳,捣烂内脏后,于     

藐小棘隙吸虫尾蚴直接感染终宿主的研究

本实验为藐小棘隙吸虫尾蚴直接经口感染终宿主人、犬的可行性研究。9只幼犬分别喂以不同数量的尾蚴(4500～88000),并于感染后3.5h～34d分别解剖。结果:实验犬藐小棘隙吸虫感染率为100％,获虫率4.01％;感染后3.5b,部分尾蚴在胃中发育成囊蚴;8b,脱囊蚴虫在小肠内发现;13d,蚴虫发育成熟,虫卵在大便中检获。两自愿者分别感染尾蚴8400条和1500条,于感染后第15d、16d自粪中检获虫卵。提示人、畜生饮含有藐小棘隙吸虫尾蚴的水可致感染。     

日本棘隙吸虫尾蚴的生态学观察

日本棘隙吸虫(Echinochasmus japonicus Ta-nabe,1926)是人、畜和禽类的寄生虫。Muto(1921)、Yamaguti(1951)、Takahashi(1953)等曾对日本棘隙吸虫的尾蚴形态作过详细描述,但未见尾蚴生态学方面的报道。为此,我们对尾蚴的生态作了某些观察。 一、尾蚴自第一中间宿主纹沼螺内逸出情况 在螺体头颈部伸出贝壳外时从右触角下方的泄殖孔逸出,尾蚴随孔内产生的冲击力被送至距孔口2mm以外     

藐小棘隙吸虫病流行病学研究 2、中间宿主感染情况及其季节消长

和县陈桥洲藐小棘隙吸虫中间宿主调查首次报告了铜锈环棱螺为藐小棘隙吸虫第一中间宿主。其自然感染呈明显的季节性变化,7月下旬至12月上旬可检到阳性螺,以9～11月份感染率最高。检查第二中间宿主淡水鱼19种(1855尾),其中17种检出囊蚴,平均感染率为83.68%。淡水鱼各月感染率变化差异无显著性,但感染度从11月至翌年4月最高。文中就该地藐小棘隙吸虫流行因素以及中间宿主感染的季节消长与气温、降雨等因素的关系作了讨论,并提出了中间宿主调查的适宜季节。     

日本棘隙吸虫生活史的实验观察

本文报告日本棘隙吸虫生活史,包括虫卵、毛蚴、胞蚴、母雷蚴、子雷蚴、尾蚴以及成虫各期的发育。虫卵置27～32℃室温孵育,8d 后毛蚴发育成熟并孵出。毛蚴感染纹沼螺后60d,在螺体内找到发育成熟的尾蚴,然后将尾蚴感染小鳉鱼,在鱼鳃获得囊蚴再感染鸽子、金黄色地鼠和幼犬,20d 后解剖获得完全成熟的虫体。     

藐小棘隙吸虫尾蚴直接感染终宿主的实验研究

本实验为用藐小棘隙吸虫尾蚴直接经口感染终宿主人、犬的研究。９只幼犬分别喂以不同数量的尾蚴（４５００～８８０００条），于感染后３．５ｈ至３４ｄ分别解剖。结果实验犬藐小棘隙吸虫感染率为１００％，获虫率４．０１％；感染后３．５ｈ，部分尾蚴在胃中发育成囊蚴；８ｈ脱囊幼虫在小肠内发现；１３ｄ，幼虫发育成熟，虫卵在大便中被检获，两名志愿者分别口服尾蚴８４００条和１５００条，于感染后第１５ｄ、１６ｄ自粪中检获虫卵。结果提示人、畜生饮含有藐小棘隙吸虫尾蚴的水可致感染。     

Melanoides tuberculata (Mollusca: Thiaridae) as an intermediate host of Centrocestus formosanus (Trematoda: Heterophyidae) in Brazil

Pleurolophocercous cercariae emerged from naturally infected Melanoides tuberculata from Minas Gerais State, Brazil, were used to perform experimental infection of laboratory-reared Poecilia reticulata. Mature metacercariae were obtained from the gills of fishes and force-fed to Mus musculus. The adult parasites which recovered from small intestines of mice were identified as Centrocestus formosanus. This is the first report of M. tuberculata as intermediate host of this heterophyid in Brazil.     

Melanoides tuberculata as intermediate host of Philophthalmus gralli in Brazil

Melanoides tuberculata that naturally harbored trematode larvae were collected at the Pampulha dam, Belo Horizonte (Minas Gerais, Brazil), during malacological surveys conducted from 2006 to 2010. From 7,164 specimens of M. tuberculata collected, 25 (0.35%) were infected by cercariae, which have been morphologically characterized as belonging to the Megalurous group, genus Philophthalmus. Excysted metacercariae were used for successful experimental infection of Gallus gallus domesticus, and adult parasites recovered from the nictitating membranes of chickens were identified as Philophthalmus gralli. This is the first report of P. gralli in M. tuberculata in Brazil.     

Studies on the morphology of cercariae obtained from freshwater snails at Erawan Waterfall, Erawan National Park, Thailand

The morphology of cercariae of freshwater snails from Erawan Waterfall, Erawan National Park, Kanchanaburi Province was studied between December 2002 and August 2003. The snail samples were collected by handpicking using a counts per unit of time sampling method. The cercariae, larva stage of a trematode, were investigated using the shedding method where they were categorized into three groups and six species. The first group, Pleurolophocercous cercariae, consists of Haplorchis pumillo (C1) and Stictodora tridactyla (C3). The second group, Furcocercous cercariae, consisted of Mesostephanus appendicalatus (C2), Transversotrema laruei (C6) and Cardicola alseae(C4). The third group, Xiphidio cercariae, has only one species which is Loxogenoides bicolor (C5). Out of 1163 snails, only 62 were found to be infected by cercariae, equivalent to a 5.33% infection rate. The infections grouped by species of the cercariae are as follows: C, 22 (1.9%), C, 29 (2.5%), C2 1 (0.1%), C6 1 (0.1%), C4 6 (0.5%) and C5 3 (0.3%). The freshwater snail samples consist of four species. From a total of 1163 samples, there are 687 Melanoides jugicostis, 91 Tarebia granifera, 296 Thiara scabra and 89 Melanoides tuberculata. Infections were found in 45 (6.5%), 6 (6.6%), 1 (0.3%) and 10 (11.2%), respectively.     

Freshwater mollusks of medical importance in Kalasin Province, northeast Thailand

A snail survey was performed in six districts around irrigation areas of Lampao Dam, in Kalasin Province. The survey caught a total of 5,479 live snails and classed them into five families, 12 genera and 15 species, of which 7 species are suspected of transmitting human parasitic diseases. The seven species were Pila polita, Pomacea canaliculata, Filopaludina (S.) m. martensi, Bithynia (Digoniostoma) siamensis goniomphalos, Melanoides tuberculata, Radix rubiginosa, and Indoplanorbis exustus. Of these, B. (D.) s. goniomphalos and I. exustus were found to harbor emergent cercariae. Only B. (D.) s. goniomphalos hosted several types of cercariae--Opisthorchis viverrini, unidentified species of intestinal flukes, echinostomes, xyphidio and furcocercous cercariae. Indoplanorbis exustus shed only echinostome cercariae. B. (D.) s. goniomphalos showed a rather high natural infection rate with O. viverrini, 1.3% in Yang Talat district, and 0.61% in Kamalasai district, in Kalasin Province.     

华支睾吸虫生活史在实验室的建立

目的 构建华支睾吸虫生活史的室内生态系统。 方法 解剖自然感染华支睾吸虫的家猫,收集华支睾吸虫虫卵,放入养殖缸内自然感染纹沼螺和长角涵螺,待尾蚴发育成熟,分离阳性螺,放入养殖缸内与各种鱼类同缸饲养,使阳性螺释放的尾蚴自然感染缸内的各种鱼类。螺类释放尾蚴后的第30天开始,定时检查鱼类的感染情况,分别采用鱼肉压片法和消化法检查各种鱼体内的感染率和感染度。分离、收集鱼肉中囊蚴感染家猫和SD大鼠。 结果 水温在24.3～37.2 ℃时,尾蚴发育成熟逸出螺体的时间需95 d。纹沼螺的感染率为12.5%（25/200）,长角涵螺为18%（9/50）。水温在20 ℃以下时,螺体内尾蚴停止逸出。鱼类感染尾蚴后形成囊蚴的时间为30 d,至囊蚴完全成熟需45 d。麦穗鱼、草鱼、鳑鮍鱼、鳙鱼、鲮鱼、鲫鱼、鲤鱼和罗非鱼体内囊蚴的感染度不尽相同,每克鱼肉含囊蚴数分别为1 792、16、8、6、5、4、4和2个。将鱼体内分离的囊蚴分别感染大鼠和家猫均获得成虫。 结论 华支睾吸虫生活史室内生态系统构建成功。     

Diversity and cercarial shedding of malaco fauna collected from water bodies of Ratnagiri district, Maharashtra

An investigation on the occurrence of snails in the water bodies of five selected sites i.e., Khed, Chiplun, Ratnagiri, Parchuri and Gimvi of district Ratnagiri, Maharashtra (India) was made during April-May 2006. The study revealed occurrence of nine species of snails viz., Indoplanorbis exustus, Lymnaea luteola, L. acuminata, Paludomus obesus, Ferrissia tenuis, Thiara (Melanoides) tuberculata, Bellamya bengalensis, B. dissimilis and Pila globosa, besides some species of bivalves. I. exustus was the most common species by occurrence in all the selected localities and next to it was L. luteola followed by T. tuberculata, B. bengalensis and B. dissimilis, in succession. Infection with liverfluke and amphistome cercariae was found in most of the collected snail species except P. globosa. However, the Schistosome infection has been reported only in I. exustus and L. luteola. The rice fields, streams and riverbeds shared most abundance of snails whereas those collected from rice fields shedded highest number of cercariae.     

异盘并殖吸虫生活史的研究

目的：在实验室完成异盘并殖吸虫生活史，为基础研究提供生物学资料。方法：以异盘并殖吸虫毛蚴人工感染武鸣拟钉螺，定期观察螺内幼虫的发育和形态特征，再以尾蚴人工感染南宁束腰蟹，定期剖检囊蚴并感染终宿主。结果：20℃－31℃室温下，卵培育16d－21d即发育成熟孵出毛蚴，毛蚴纤毛板四列（6、7、3、1），第一列每块下部具凹陷和缺刻；毛蚴感染拟钉螺，室温21℃－30℃时，胞蚴、母雷蚴、子雷蚴（含游离尾蚴）分别于感染后第26、41、58d发育成熟，前者可见产孔，后二者原肠与体长比例分别为1∶3、1∶6；尾蚴具并殖吸虫的一般特征，焰细胞数目及排列方式是2［（2＋2＋2）＋（2＋2＋2）］＝24；束腰蟹经口喂饲尾蚴或饲养于阳性螺环境中，均可受染，60d获成熟囊蚴（室温16℃－27℃），以此囊蚴感染适宜终宿主（猫、大鼠），获得异盘并殖吸虫成虫。对各期幼虫及成虫的形态均作了描述。结论: 在实验室首次成功地完成了异盘并殖吸虫的生活史, 使本虫生活史的主要环节得到阐明。     

Helminths of freshwater animals from five provinces in northern Thailand

Seven species of fishes, 6 species of mollusks, 1 species of crab, and 1 species of shrimp were collected from 12 natural freshwater sites from 5 provinces: Lumpang, Phrae, Phayao, Chiang Rai and Chiang Mai during the Rainy season of 2000. Fishes, Channa striatus, Dermogenus pusillus, Oxyeleotris marmoratus, Trichogaster trichopterus and Trichopsis vittatus were examined for helminths and 34.69% (17/49) were infected. There were 2 genera of monogenean identified as follows: Dactylogyrus and Trianchoratus; 3 genera of metacercariae were as follows: Acanthostomum, Posthodiplostomum and Stellantchasmus. Furthermore, 1 genus of Acanthocephala was found from fishes to be Pallisentis sp. The prevalence of infection in mollusks was 6.20% (17/274); Pleurolophocercous and Furcocercous cercariae were observed only in one species of mollusks, Melanoides sp. A crab and a shrimp were negative.     

Distribution patterns and cercarial shedding of Bulinus nasutus and other snails in the Msambweni area, Coast Province, Kenya

In the Msambweni area of the Kwale District in Kenya, an area endemic for Schistosoma haematobium, potential intermediate-host snails were systematically surveyed in water bodies associated with human contact that were previously surveyed in the 1980s. Bulinus (africanus) nasutus, which accounted for 67% of the snails collected, was the only snail shedding S. haematobium cercariae. Lanistes purpureus was the second most common snail (25%); lower numbers of Bulinus forskalii and Melanoides tuberculata were also recovered. Infection with non-S. haematobium trematodes was found among all snail species. Rainfall was significantly associated with the temporal distribution of all snail species: high numbers of Bulinus nasutus developed after extensive rainfall, followed, in turn, by increased S. haematobium shedding. Spatial distribution of snails was significantly clustered over a range of up to 1 km, with peak clustering observed at a distance of 400 meters. Water lily (Nymphaea spp.) and several aquatic grass species appeared necessary for local colonization by B. nasutus or L. purpureus.