Infective Investigation And Biological Characteriscits Research From Snake Plerocercoids In Anshun Guizhou

Objective : To investigate the infection statua and study biological characteristics of snake pleroceroids in Guizhou Anshun. Methods:The wild snakes were caught,identified and dissected,then date of parasitic pleroceroids was recorded and analysed. ①A total of 12 kunming mice were divided into 2 groups,a group was orally infected free pleroceroids,while another group was infected encapsulated pleroceroids(6 maice/each group,5 pleroceroids/each mouse),then the infective rates of two groups wete recorded; ②80 mice were equally divided into 8 groups(10 mice/each group,3 pleroceroids/each mouse),the mice in group 1-4 were inoculated with pleroceroids treated with 100% snake bile for 0.5,3,6or12 h,the mice in group 5-8 were inoculated with pleroceroids treated with normal saline for 0.5,3,6oe12 h,served as controls;③20 mice were equally divided into 2 groups, 10 mice/each group, the mice in group 1 were infected snake pleroceroids,the mice in group 2 were infected frog pleroceroids,then the infective rates of two groups wete recorded after two weeks.Resμlt : ①Among 50 snakes examined,78.0%(39/50)were infected with pleroceroids in the rang of 2~347 worms per affected snake;②The pleroceroids settled down mainly subcutaneous tissue(45.2%),muscle tissue(39.8%)and body cavity(15.0%);③The pathological status of pleroceroids found in snakes were calssified as free,encapsulated and degenerative stages.The infected rate of the mice fed with free or encapsulateds pleroceroids was 43.33% and 56.67% respectively(P>0.05);④The infectivity of the pleroceroids treated by snake bile for 0.5-12 h was similar to the control(P>0.05).The reaction of snake muscular tissue infected by free stages was quite mild revealing only simple compression of surrounding tissue and a few neutrophile leucocyte infiltration. The some worms were encapsulated by thin and delicate fibrous tissue.The cyst wall contained a few acute inflammatory cells and the worms in cyst were activity. The cyst size of degenerative stage was usually smaller than that of encapsulated stage. Microscopically the degenerative stage had a thick fibrous wall with mainly lymphocytes,the pleroceroids in degenerative cyst were replaced gradually by necrotic tissue of structureless worms and amorphous materials with infective time extending;⑤The infected rate of the mice fed with snake pleroceroids or frog pleroceroids was 66% and 74% respectively(P>0.05).Conclusion:The infection of pleroceroids in wild snakes was serious fairly in Guizhou Anshun,and the natural infection of snakes might cause food safety problems.The survey of infective rate and study of biological characteristics on snake plerocercoids would be helpful to lay a foundation for prevention and treatment of plerocercoidosis.