异盘并殖吸虫生活史的研究

STUDIES ON THE LIFE CYCLE OF PARAGONIMUS HETEROTREMUS

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。

AIM:In order to clarify the biological features of the lung fluke, Paragonimus heterotremus , it is necessary to replicate its complete life cycle in the laboratory. METHODS: Tricula wumingensis infected with the miracidiae of P.heterotremus were regularly dissected after infection for larvae observation. The cercariae of P. heterotremus from positive snails were used for experimental infection of the crab, Samanniathelphusa nanningensis . The crabs were then examined for the metacercariae at regular intervals. The infection of mammals ( cats and rats) was performed with the metacercariae obtained from exerimentally infected crabs. RESULTS: The miracidia were hatched by incubating the eggs in water (room temperature 20 ℃ to 31 ℃) for 16 days to 21 days. The epidermal cells of the miracidia were arranged in 4 transverse rows,6 in the first row, 7 in the second, 3 in the third, and a single terminal cell at the posterior end of the body.The cells of the first row have indentation in their bases.Mature sporocysts, first generation rediae and second generation rediae(containing dissociative cercariae),were found on the 26th day,41 st day and 58th day after infection of the snails respectively( room temperature 21℃-30℃).The sporocyst had a birth pore at its anterior tip.The length ratio of the gut to the body was 1∶3 in the first and 1∶6 in the second generation rediae. The mature second generation rediae contains 5-21 mature cercariae which emerge from its pharynx. The cercaria has general characteristics of Paragonimus . Its flame cell pattern was formulated as 2[(2+2+2)+(2+2+2)]=24.After the infection of crabs with cercariae, the mature metacercariae were found in the crabs on the 60 th day. The crabs could be successfully infected by either: giving mature cercariae orally to them or raising them in water with postive snails. After the metacercariae obtained from experimental crabs were given to cats and rats, P. heterotremus adult worms were recovered from the worm cyst in their lungs. The morphology of various larval stages and adult worms were described.CONCLUSION: The life cycle of P. heterotremus was completed for the first time in the laboratory. The whole life cycle from egg to adult worm has been described in the present study.