异地子代钉螺对日本血吸虫的易感性研究

Progeny snails from a distant location experimental study on the susceptibility of Schistosoma japonicum

目的观察异地子代成(新)螺、子代幼螺对日本血吸虫的易感性和存活情况,为血吸虫病监测预警(哨鼠疫水测定)和防治提供科学依据。方法在安徽安庆和江苏南京采集野外成(老)螺,在现场控制条件下自然繁殖,获取子代成(新)螺和幼螺,然后在室内人工感染无锡株日本血吸虫毛蚴(20条/只),并经饲养70d后分别解剖观察其感染情况及生存率。结果安庆和南京同龄成(老)螺的子代成(新)螺和幼螺毛蚴感染率分别为40.63%(91/224)、36.36%(88/242)和18.23%(33/181)、13.85%(27/195),差异均无统计学意义(χ2=0.892 92、1.346 41,P均>0.05);而两地子代成(新)螺与子代幼螺的感染率比较,则差异有统计学意义(χ2=29.568 3,P<0.01)。两地人工感染后的同龄子代成(新)螺和幼螺生存率分别为74.67%(224/300)、80.67%(242/300)和60.33%(181/300)、65.00%(195/300),差异均无统计学意义(χ2子代成螺=3.113 19、χ2子代幼螺=1.396 28,P均>0.05);但同地子代成(新)螺的存活率与子代幼螺比较差异有统计学意义(χ2安庆=14.047 5、χ2南京=18.607 1,P均<0.01)。结论安庆和南京两地子代成(新)螺及子代幼螺在实验室条件下均能感染无锡株日本血吸虫毛蚴,其感染率前者高于后者。因此,建议在现场开展哨螺测定时宜选择新鲜且活力强的成(新)螺为佳。

Objective To observe the susceptibility to Schistosoma japonicum and survival in snails from a distant location and their recent progeny upon manual infection with miracidia of S.japonicum in order to provide a basis for control work and surveillance.Methods Adult snails were collected from the countryside in Anqing and Nanjing and then bred under natural conditions on-site to obtain adult and young snails.Snails were manually infected indoors with miracidia of the Wuxi strain of S.japonicum（20 miracidia per snail）.After 70 days of care,the snails were dissected to observe the state of infection and determine survival.Results The rate of infection in snails of the same age from Anqing and Nanjing,adult snails bred on-site,and their recent progeny was 40.63%（91/224）,36.36%（88/242）,18.23%（33/181）,and 13.85%（27/195）,respectively.Differences in the rate of infection were not statistically significant（χ2=0.89292,1.34641,P0.05）.The rate of infection in adult snails differed significantly from that in young snails（χ2=29.5683,P0.01）.The survival rate of the manually infected snails of the same age from Nanjing and Anqing was 74.67%（224/300） and 80.67%（242/300） vs.60.33%（181/300） and 65.00%（195/300）,respectively.Differences in the rate of infection were not statistically significant（χ2adults=3.11319,χ2recent progeny=1.39628,P0.05）.The survival rate of adult snails from the same areas differed significantly from that of young snails（χ2Anqing=14.0475,χ2Nanjing=18.6071,P0.01）.Conclusion Adult and young progeny of snails from Anqing and Nanjing were both susceptible to infection with miracidia of the Wuxi strain of S.japonicum.Adult snails bred on-site had a higher rate of infection than did their progeny.This finding suggests that fresh and vital snails be selected when surveilling sentinel snails in the field.