de Souza C P, Jannotti-Passos L K, Ferreira S S, Sampaio I B
Centro de Pesquisas René Rachou, FIOCRUZ, Belo Horizonte, MG, Brasil.
Rev Inst Med Trop Sao Paulo. 1995 Jul-Aug;37(4):319-24. doi: 10.1590/s0036-46651995000400006.
In these experiments the ratio of male to female S. mansoni larvae in B. glabrata from Belo Horizonte and Ribeirão das Neves Minas Gerais, Brazil, either reared in laboratory or collected in the field, varied from 1:1 to 1:1.3 or 1.4:1. Cercariae of LE strain of Schistosoma mansoni, shed by 39 snails maintained at 25 +/- 0.5 degrees C were used to infect mice on a weekly basis. Subsequent perfusion resulted in 76.6% male and 23.4% female worms. The cercariae produced by 32 infected snails maintained at 27 +/- 0.5 degrees C were inoculated into mice and produced 43.4% male and 56.6% female worms (p < 0.05). Cercariae eliminated by snails collected in Barreiro and Ressaca, Belo Horizonte, during hot months, produced 45.7 to 47.7% male and 52.3 to 54.3% female worms. A lower number of cercariae shed by snails collected in Gorduras, Belo Horizonte, at 20 +/- 3.0 degrees C, produced 51.6% male and 48.4% female worms. Thus, in this region the infection of vertebrate hosts with S. mansoni cercariae would be more severe in the summer due to the higher level of parasites and the number of eggs.
在这些实验中，来自巴西米纳斯吉拉斯州贝洛奥里藏特和里贝朗达斯内维斯的光滑双脐螺中曼氏血吸虫雌雄幼虫的比例，无论是在实验室饲养还是在野外采集的，都在1:1至1:1.3或1.4:1之间变化。曼氏血吸虫LE株的尾蚴由39只饲养在25±0.5摄氏度的蜗牛每周排出，用于感染小鼠。随后的灌注结果显示，雄虫占76.6%，雌虫占23.4%。由32只饲养在27±0.5摄氏度的受感染蜗牛产生的尾蚴接种到小鼠体内，产生了43.4%的雄虫和56.6%的雌虫（p<0.05）。在炎热月份从贝洛奥里藏特的巴雷罗和雷萨卡采集的蜗牛排出的尾蚴，产生了45.7%至47.7%的雄虫和52.3%至54.3%的雌虫。在贝洛奥里藏特的戈尔杜拉斯，在20±3.0摄氏度下采集的蜗牛排出的尾蚴数量较少，产生了51.6%的雄虫和48.4%的雌虫。因此，在该地区，由于寄生虫水平较高和虫卵数量较多，夏季曼氏血吸虫尾蚴对脊椎动物宿主的感染可能会更严重。
