广州管圆线虫生活史的实验室构建与观察

目的实验室构建广州管圆线虫生活史，进一步了解其生长变化及其致病性，为广州管圆线虫病的防治提供基础资料。方法福建省采集的广州管圆线虫L3经口、腹腔注射、皮下注射和皮肤接触等途径感染SD大白鼠，观察感染效果。从SD大白鼠粪便中获得广州管圆线虫L1，感染人工繁殖的福建子代福寿螺，25．5～26．5℃条件下，分别置于无水环境和水族环境饲养，观察广州管圆线虫在宿主体内的生长规律、发育进程、分布状况、不同发育期幼虫形态特征及诱导的病理变化等。结果L3经口感染的感染率较其他感染途径为好；无水环境中的福寿螺在休眠状态不影响广州管圆线虫发育；实验室完成一个广州管圆线虫生活史最短为50d；休眠状态螺体L3出现前期为16．5d，水族环境螺L3出现前期为18．5d，鼠粪L1开放前期为33．5d。L3主要分布于感染螺的肺、肌肉及肝脏等处，螺肺囊可出现明显的L2、L3结节病理表现。折光颗粒、头部特征、鞘膜变化是各期幼虫形态特征的主要鉴别指标。观察期感染鼠多数死亡，虫卵诱导的肺纤维化和肺动脉虫栓是主要死因。结论经口感染大白鼠及感染性螺置休眠状态是维持实验室广州管圆线虫生活史较好的方式。广州管圆线虫生活史长短取决于中间宿主及环境温度。螺肺的特殊结构和幼虫结节病理表现为创立新的检测方法奠定了基础。

Establishment and observation of the life cycle of Angiostrongylus cantonensis in a laboratory setting

Objective To establish and observe the life cycle of Angiostrongylus cantonensis in a laboratory setting and to further understand the growth and development process and pathogenicity of A. cantonensis in hosts in order to provide basic information for disease control. Methods SD rats were infected by third stage larvae （L3） of A. cantonensis collected from Fujian Province via intragastric injection, peritoneal injection, subcutaneous injection, and skin exposure. Descendants of Pomacea canaliculata snails from Fujian Province were infected with first stage larvae （L1） of A. cantonensis and then divided into two groups and placed in an aquatic environment or an environment without water. Both settings were kept at 25.5--26.5 ℃. The growth and development process, morphology, distribution, and pathogenicity of A. cantonensis larvae living in snails and rats were observed. Results Intragastric injection led to a higher rate of infection than other forms of infection. The dormancy of snails in the environment without water had little effect on the growth and development of A. cantonensis larvae in snails. In the laboratory, a single life cycle was completed in 50 days at the shortest. L3 of the parasite developed about 16.5 days after infection in dormant snails in a dry environment without water, while it developed about 18.5 days after infection in an aquatic environment. L1 hatched in rat feces about 33.5 days after infection. L3 was mainly distributed in the lung, muscle, and liver of infected snails. Infected snails had lung walls with capsules containing larvae that displayed nodular pathology. The distribution of refractive granules, head features, and sheath variation were the main features used to morphologically distinguish the stages of larval development in snails. Definitive hosts （rats） mainly died of pulmonary fibrosis due to worm eggs and parasitic emboli. Conclusion Intragastrie injection and use of dormant P. canaliculata were effective ways of maintaining the life cycle of A. cantone