旋毛虫成囊前期幼虫感染性观察

Observation on the infectivity of pre-encapsulated larvae of Trichinella spiralis

目的观察旋毛虫成囊前期幼虫的感染性。方法将80只雄性昆明小鼠随机分成8组,每只感染300条旋毛虫肌幼虫,感染后14～21d每天剖杀1组,将小鼠膈肌(即含9～16日龄的成囊前期幼虫)分别再喂饲10只小鼠:同时将贝氏法收集的9～16日龄的幼虫用灌胃法感染10只小鼠(每只300条)。感染后42 d将2种方法感染的小鼠剖杀,分别剪碎肌肉,人工消化后收集并计数旋毛虫肌幼虫。光学显微镜下观察不同日龄幼虫的形态并测量其长度。结果旋毛虫9～12日龄幼虫2种方法感染的小鼠均未检获肌幼虫;13～16日龄幼虫膈肌喂饲法小鼠的感染率均为100%,幼虫灌胃法对小鼠的感染率分别为30%、30%、40%和40%。幼虫日龄与喂饲法在感染小鼠后42d收集的肌幼虫数呈相关性(r=0.939,P<0.05)。旋毛虫9～16日龄幼虫长度随幼虫日龄的延长而增大,9日龄幼多呈腊肠状,未见虫体活幼;12日龄幼虫多呈卷曲状,可见缓慢蠕动;15日龄幼虫呈明显的卷曲状,幼虫周围已形成明显的囊包,可见虫体明显活动。结论旋毛虫感染后18d的成囊前期幼虫(13日龄)对新宿主具有感染性,幼虫的感染性与长度随着日龄的延长而增大。

Objective To observe the infectivity of pre-encapsulated larvae of Trichinella spiralis. Methods Eighty male Kunming mice were randomly divided into 8 groups (10 mice per group), each mouse was inoculated with 300 muscle larvae of T. spiralis. One group of the infected mice was daily killed 14-21d after infection. The diaphragms contained pre-encapsulated larvae with 9-16 day-old were respectively given to another 10 mice by feeding method,the pre-encapsulated larvae with 9-16 day-old collected by Baermann's method were respectively applied to infect another 10 mice by intragastric injection (300 larvae per mouse). All mice infected were killed 42d after infection, muscles were cut into pieces and digested by artificial digestion method, the muscle larvae were collected and numbered. The morphology of the pre-encapsulated larvae with different day-old was observed and the length was measured under microscope. Results No muscle larvae were found in mice infected with 9-16 day-old larvae by two methods. The infection rate of mice inoculated with 9-16 day-old larvae by feeding method was 100%. The infection rate of mice inoculated by stomach perfusion was 30%,30%,40% and 40%, respectively. There was a correlation between the larval day-old and number of muscle larvae collected 42d after infection in mice infected by feeding method (r= 0.939,P<0.05). The length of larvae with 9-16 day-old increased with the prolongation of the day-old larvae. Most of the larvae with 9 day-old was sausage-like and immobile, a majority of the larvae with 12 day-old was spiral and moved slowly, the larvae with 15 day-old was spiral and moved obviously, the capsule around larvae have been formed. Conclusion The pre-encapsulated T. spiralis larvae collected 18d after infection (with 13 day-old) have the infectivity to new hosts, the infectivity and length of larvae increase with the prolongation of the larval day-old.