2015—2020年四川省石渠县小型哺乳类动物棘球蚴感染率调查

Prevalence of Echinococcus infection in small mammals captured from Shiqu County,Sichuan Province from 2015 to 2020

目的了解四川省石渠县小型哺乳类动物棘球蚴感染率及变化趋势,为当地棘球蚴病防控提供科学依据。方法2015—2020年,选择石渠县人体多房棘球蚴病流行较重的9个乡(镇),每个乡(镇)各选1个小型哺乳类动物活动频繁的区域作为调查点。每年7—8月,在各调查点均设置2个50 m×50 m的样方,捕捉样方内小型哺乳类动物并记录其形态学特征等数据,通过形态学方法鉴定其物种。现场解剖所捕获小型哺乳类动物,采用目检法判断是否其感染棘球蚴;采集感染动物病变脏器,采用PCR法检测棘球蚴感染情况,并鉴定棘球蚴虫种。计算各种小型哺乳类动物棘球蚴感染率,分析感染率随时间变化趋势,并对目检法和PCR法检测结果进行比较。结果2015—2020年共在石渠县调查点捕捉小型哺乳类动物2692只,经形态学鉴定,其中青海田鼠1360只(50.52%)、高原鼠兔1332只(49.48%)。2015—2020年,目检法小型哺乳类动物棘球蚴感染总阳性率分别为35.63%、19.16%、21.41%、8.40%、7.68%、4.44%,PCR法检测总阳性率分别为18.96%、5.36%、5.61%、4.58%、3.30%、0.37%,均呈逐年下降趋势(χ^(2)=215.024、117.045,P均<0.001)。除2018年外,其余各年目检法棘球蚴感染阳性率均高于PCR法(χ^(2)=33.597、21.815、51.373、17.268、9.537,P均<0.01)。PCR法检测结果显示,2015—2020年石渠县小型哺乳类动物多房棘球蚴感染阳性率从10.21%降至0.37%,石渠棘球蚴感染阳性率从8.75%降至0,均呈逐年下降趋势(χ^(2)=117.045、43.436,P均<0.001);青海田鼠多房棘球蚴感染阳性率从15.19%降至0.45%,石渠棘球蚴感染阳性率从8.23%降至0;高原鼠兔多房棘球蚴感染阳性率从7.76%降至0,石渠棘球蚴感染阳性率从9.01%降至0。结论青海田鼠和高原鼠兔为四川省石渠县小型哺乳类动物优势种。青海田鼠以多房棘球蚴感染为主,高原鼠兔以石渠棘球蚴感染为主;两类动物棘球蚴感染阳性率均呈逐年下降趋势。

Objective To investigate the prevalence of Echinococcus infection in small mammals in Shiqu County,Sichuan Province from 2015 to 2020,so as to provide insights into echinococcosis control in Shiqu County.Methods One setting with frequent activity of small mammals was sampled as the survey site from each of 9 townships where human alveolar echinococcosis was hyperendemic,in Shiqu County,Sichuan Province from 2015 to 2020.Two quadrats measuring 50 m×50 m were assigned in each survey site during the period between July and August from 2015 to 2020 to capture all small mammals in quadrats,and the species of small mammals were identified by morphological characteristics.All captured small mammals were dissected in the field and Echinococcus infection was identified by visual examinations.The affected organs of Echinococcus-infected small mammals were collected,and Echinococcus infection was detected using PCR assay,with Echinococcus species characterized.The prevalence of Echinococcus infection was calculated in small mammals,and the trends in the prevalence of Echinococcus infection were analyzed during the period from 2015 to 2020.In addition,the prevalence of Echinococcus infection was compared in small mammals using visual examinations and PCR assay.Results A total of 2692 small mammals were captured in the survey sites of Shiqu County from 2015 to 2020,and morphology characterized 1360 Microtus fuscus(50.52%)and 1332 Plateau pika(49.48%).The prevalence rates of Echinococcus infection were 35.63%,19.16%,21.41%,8.40%,7.68% and 4.44% by visual examinations and 18.96%,5.36%,5.61%,4.58%,3.30% and 0.37% by PCR assay in small mammals in Shiqu County from 2015to 2020,both showing a tendency towards a decline year by year(χ^(2)=215.024 and 117.045,both P values<0.001).The prevalence of Echinococcus infection was significantly higher in small mammals by visual examinations than by PCR assay during the period from 2015 to 2020 except in 2018(χ^(2)=33.597,21.815,51.373,17.268 and 9.537,all P values<0.01).PCR assay detected a reduction in the prevalence of E.multilocularis infection from 10.21% to 0.37% and a reduction in the prevalence of E.shiquicus infection from 8.75% to 0 in small mammals in Shiqu County from 2015 to 2020,both appearing a tendency towards a decline year by year(χ^(2)=117.045 and 43.436,both P values<0.001).In addition,the prevalence of E.multilocularis and E.shiquicus infections reduced from 15.19% to 0.45% and from 8.23% to 0 in M.fuscus,and the prevalence of E.multilocularis and E.shiquicus infections reduced from 7.76% to 0 and from 9.01% to 0 in P.pika in Shiqu County from 2015 to 2020.Conclusions M.fuscus and P.pika were dominant species of small mammals in Shiqu County,Sichuan Province from 2015 to 2020,and E.multilocularis infection was mainly found in M.fuscus and E.shiquicus infection mainly found in P.pika.The prevalence of Echinococcus infection appeared a tendency towards a decline in both M.fuscus and P.pika year by year during the period from 2015 to 2020.