目的 了解四川省色达县野外棘球绦虫终末宿主粪便污染情况及特征,为制定野外传染源的防控策略提供依据。 方法 2020年10月,采用机械抽样方法,沿色达县主要交通路线及野外放牧路线每隔1~2 km抽取1个调查点,记录调查点地理位置、终末宿主粪便数量、牧场类型、地形类别、植被类型、植被覆盖度、平均草高度、小型哺乳动物密度和终末宿主粪样种类等信息。采集调查点内犬科动物粪样,提取粪样DNA,PCR检测粪样棘球绦虫感染情况。PCR阳性产物送测序,测序结果在NCBI数据库中进行比对,判定感染的虫种。使用SPSS 18.0 软件对终末宿主粪便污染情况及特征进行统计分析。 结果 共选取40个调查点,34个调查点有犬科动物粪便分布（占85.00%）,其中17个调查点有棘球绦虫阳性粪便分布（占42.50%）。共收集犬科动物粪样227份,PCR检测结果显示,粪便棘球绦虫阳性率、石渠棘球绦虫（Es）阳性率、多房棘球绦虫（Em）阳性率分别为18.06%（41/227）、14.10%（32/227）、4.85%（11/227）,其中混合感染Es和Em粪样2份,未发现细粒棘球绦虫阳性粪便。不同牧场类型中,冬季牧场和夏季牧场粪便棘球绦虫阳性率分别为19.90%（40/201）和3.85%（1/26）（P > 0.05）;冬季牧场粪便Es阳性率为15.92%（32/201）,高于夏季牧场的0（0/26）（P < 0.05）。不同地形类别中,平坝、山坡和河滩的粪便棘球绦虫阳性率、Es阳性率和Em阳性率差异均无统计学意义（P > 0.05）。不同植被类型中,高寒草甸和高寒灌木丛草甸粪便棘球绦虫阳性率、Es阳性率和Em阳性率差异均无统计学意义（P > 0.05）;高寒草甸的粪便密度（7.17份/10 000 m²）高于高寒灌木丛草甸（3.44份/10 000 m²）（Z = -2.376,P < 0.05）。稀疏、较为稀疏、中等、较密集、密集等不同植被覆盖度的粪便棘球绦虫阳性率、Es和Em阳性率差异均无统计学意义（P > 0.05）。≤ 5 cm、6~10 cm、11~15 cm和≥ 16 cm等不同平均草高度的粪便棘球绦虫阳性率、Es和Em阳性率差异均无统计学意义（P > 0.05）。小型哺乳动物密度为401~600个/10 000 m²的粪便密度为12.25份/10 000 m²,高于≤ 200个/10 000 m²的3.32份/10 000 m²（Z = -2.738, P < 0.008）;小型哺乳动物密度为≥ 601个/10 000 m²的粪便Es阳性率为29.73%（11/37）,高于≤ 200个/10 000 m²的5.48%（4/73）（χ² = 12.261, P < 0.008）。狐粪的棘球绦虫阳性率和Es阳性率分别为25.95%（34/131）和22.14%（29/131）,均高于犬粪的7.45%（7/94）和3.19%（3/94）（χ ² = 12.580、16.103,P < 0.05）。犬粪和狐粪Em阳性率分别为5.32%（5/94）和4.58%（6/131）,差异无统计学意义（P > 0.05）。结论 四川省色达县野外环境棘球绦虫终末宿主粪便污染严重,狐狸是主要传染源,犬粪Em阳性率高,冬季牧场、高寒草甸、小型哺乳动物密度较高的地区可作为野外传染源防控工作的重点区域。

Objective To understand the feces contamination and characteristics of definitive hosts of Echinococcus in the field in Seda County, Sichuan Province, to provide a basis for a prevention and control strategy of the source of infection in the field. Methods In October 2020, survey spots were selected every 1-2 km apart along the main traffic routes and field grazing routes in Seda County using mechanical sampling method to record their geographic location, number of feces found, pasture type, topographic type, vegetation type, vegetation coverage, mean height of grass, small mammal densities, and feces type of definitive hosts. Canine fecal samples were collected from survey spots, and the DNA was extracted from fthe samples for detecting the infection of Echinococcus by PCR. PCR-positive products were sent for sequencing, and the sequences were compared against the NCBI database to determine the species of Echinococcus. SPSS 18.0 software was used to statistically analyze the field contamination of definitive hosts’ feces and its characteristics. Results In total, 40 survey spots were selected, among them 34 (85.00%) were found having canine feces, while Echinococcus-positive feces were detected in 17 survey spots (42.50%). A total of 227 canine fecal samples were collected and examined by PCR, revealing the positive rates of Echinococcus spp., E. shiquicus(Es) and E. multilocularis (Em) were 18.06% (41/227), 14.10% (32/227), and 4.85% (11/227), respectively. Among these samples, two were of mixed infection of Es and Em, while no Eg-positive feces was found. The fecal-positive rate of Echinococcus in winter and summer pastures was 19.90% (40/201) and 3.85% (1/26), respectively (P > 0.05). The fecal-positive rate of Es in winter pasture was 15.92% (32/201) higher than that in summer pasture (0, 0/26) (P < 0.05). There was no significant differences in fecal-positive rates of Echinococcus, Es, and Em on plain, hillside, and benchland sites(P > 0.05). Among the different vegetation types, there were no significant differences in the positive rates of Echinococcus, Es, and Em in fecal samples between altitude cold meadow and altitude cold bush-meadow. The feces density in altitude cold meadow (7.17/10 000 m ²) was higher than that of altitude cold bush-meadow (3.44/10 000 m²) (Z = -2.376, P < 0.05). There was no significant difference in the fecal-positive rates of Echinococcus, Es, and Em in areas with sparse, relatively sparse, medium, relatively dense, and dense vegetation coverage (P > 0.05). Among different mean grass heights, theere was no significant difference in the fecal-positive rates of Echinococcus, Es, and Em at mean grass heights ≤ 5 cm, 6-10 cm, 11-15 cm and ≥ 16 cm(P > 0.05). The small mammals density 401-600 heads/10 000 m² rendered the feces density 12.25/10 000 m², which was higher than that at the mammal density ≤ 200 heads/10 000 m ² (3.32/10 000 m²) (Z = -2.738, P < 0.008). The fecal-positive rates of Es at the mammal density≥ 601 heads/10 000 m² was 29.73% (11/37), which was higher than the positive rate 5.48% (4/73) at the density ≤ 200 heads/10 000 m ² (χ² = 12.261, P < 0.008). The fox fecal-positive rates of Echinococcus and Es were 25.95% (34/131) and 22.14% (29/131), respectively, which were both higher than that of canine feces (7.45%, 7/94; 3.19%, 3/94) (χ ² = 12.580, 16.103, P < 0.05). There was no significant difference in the positive rate of Em between dog feces (5.32%, 5/94) and fox feces (4.58%, 6/131) (P > 0.05). Conclusion The field surveyed in Seda County, Sichuan Province is highly contaminated by Echinococcus of definitive hosts’ feces, showing foxes as the main source of infection, high Em positive rate in dog feces, in Seda County, Sichuan Province. It was demonstrated that winter pasture, altitude cold meadow, and areas with high densities of small mammals may the key areas for control of sources of infection in the wild.