日本血吸虫单性感染虫体与复性感染虫体的比较

Comparison of Schistosoma japonicum development between single sexual infection and double sexual infection in mice and rabbits

目的对单性感染或复性感染钉螺的日本血吸虫发育结果进行观察。方法采用单个毛蚴感染单个钉螺,26℃恒温箱中饲养,60 d后逸蚴感染小白鼠(单性感染),40 d后解剖小白鼠,以检获的成虫性别鉴别各个钉螺中的尾蚴性别。再分别以单性尾蚴和混合双性尾蚴感染鼠、兔,40 d后解剖观察宿主感染情况及虫体。结果单性感染小鼠和兔后解剖获得日本血吸虫雄虫或雌虫。复性感染小鼠或兔后检出的虫体主要有3种形态:雌雄合抱、雄虫和雌虫,极少数能看到雄虫合抱未发育成熟雌虫的现象。单性感染的鼠、兔肝脏均未见虫卵,而复性感染的鼠、兔肝脏均查见虫卵。单性感染的雄虫能发育成熟,但体型较合抱成熟的雄虫略小,仅凭肉眼难以与合抱成熟雄虫区分;而单性感染的雌虫则不能发育成熟,镜下卵巢不易见到或仅见到雏形,体型明显细小。结论单性感染的雄虫和雌虫体型比复性感染合抱成熟的雄虫和雌虫的体型小,单性感染的雄虫能发育成熟,而雌虫则不能发育成熟。在解剖哨鼠时,即使未查见肝脏虫卵,仍需检查肠粘膜血管中是否有单性感染的血吸虫。

Objective To observe the development of Schistosoma japonicum after single sexual infection and double sexual infection respectively. Methods A single Oncomelania hupensis snail was infected by a single schistosome miracidium. The lar？va were induced and released from the snail after 60？day incubation at 26℃. The mice were infected by the larva（single sexual infection）and dissected 40 days after the infection. All the worms were collected and the sex of the larvae was determined by the sex of the adult worms. Then,the mice and rabbits were infected by single sex of larvae（single sexual infection）and double sex of larvae（double sexual infection）respectively. The mice and the rabbits were dissected 40 days after the infection. All the worms were collected and measured under a microscope. Results All the male or female worms were collected from the mice and rabbits after single sexual infection. There were three main forms of worms after dissection of double sexual infection of mice and rabbits：folded mature male and female,male or female. Few folded male and immature female were found. Only the double sexual larva infected mice or rabbits had schistosome eggs in the liver and the liver had typical schistosome egg nodules. The sin？gle sexual larva infected mice or rabbits had no schistosome eggs or schistosome egg nodules in the liver tissues. The single male larva could develop to worms with the testis,and with a little smaller size compared to the mature folded male,while the single sexual infection female worm could not develop to the mature stage with much thinner and smaller compared to the mature folded female. Conclusions The male or female worms from single sexual infection are smaller than those from double sexual infection （mature worms？folded male and female）. So it is necessary to check single sex worms in vessels of intestinal mucosa thoroughly in the sentinel mice when no schistosome eggs were found in the liver.