Objective: To investigate the distribution characteristics of Oncomelania hupensis in Guangxi Zhuang Autonomous Region, so as to provide insights into the assessment of the risk of schistosomiasis transmission and the scientific formulation of the schistosomiasis surveillance strategy.
Methods: From 2015 to 2019, a total of 19 national schistosomiasis surveillance sites were assigned in Guangxi Zhuang Autonomous Region, including 4 fixed sites and 15 mobile sites. Snail survey was performed by means of systematic sampling in combination with environmental sampling, and the infection of Schistosoma japonicum was detected by the crushing method combined with loop-mediated isothermal amplification (LAMP) assay.
Results: From 2015 to 2019, snail habitats were detected at areas of 17 040 to 39 527 m2, including 6 214 m2 emerging snail habitats and 16 563 m2 re-emerging snail habitats. The overall mean density of living snails was 0.019 2 snails/0.1 m2 and the occurrence of frames with snails was 1.11% in the national schistosomiasis surveillance sites; however, no S. japonicum infection was identified in snails. The area of snail habitats increased by 121.46% in the national surveillance sites in 2019 as compared to that in 2015; however, 50.34% (Z = -0.422, P > 0.05) and 42.85% (χ2 = 130.41, P < 0.01) reductions were seen in the overall means density of living snails and the occurrence of frames with snails. All snail habitats were distributed in the 4 fixed surveillance sites, and were mainly found in ditches, paddy fields and dry lands, with weeds as the primary vegetation type.
Conclusions: There are still risk factors leading to re-emergent transmission of schistosomiasis in Guangxi Zhuang Autonomous Region, such as local snail spread, and the monitoring of schistosomiasis remains to be reinforced to further consolidate the achievements of schistosomiasis elimination in the region.
［摘要］ 目的 了解广西壮族自治区钉螺分布特征, 为评估血吸虫病传播风险、科学制定血吸虫病监测方案提供参考依 据。方法 2015—2019年, 在广西壮族自治区设立19个国家血吸虫病监测点, 其中固定监测点4个、流动监测点15个, 每 年采用系统抽样结合环境抽查法进行钉螺分布调查, 对查获的钉螺采用压碎镜检法结合环介导等温扩增技术 (LAMP) 检 测血吸虫感染性。结果 2015—2019年, 广西壮族自治区19个国家血吸虫病监测点累计发现有螺面积17 040 ~ 39 527 m2, 其中新发现有螺面积6 214 m2、复现有螺面积16 563 m2, 活螺平均密度和有螺框出现率分别为0.019 2 只/0.1 m2和 1.11%, 未发现血吸虫感染性钉螺。与2015 年相比, 2019 年广西壮族自治区国家血吸虫病监测点有螺面积增加了 121.46%, 但总活螺平均密度和有螺框出现率分别下降了50.34% (Z = −0.422, P > 0.05)和42.85% (χ2 = 130.41, P < 0.01) 。发现的有螺环境均分布于4个固定监测点, 钉螺分布主要环境类型为沟渠、水田、旱地等, 主要植被类型为杂草。结论 广西壮族自治区存在钉螺局部扩散等血吸虫病再传播的风险因素。今后仍需加强钉螺监测工作, 进一步巩固血吸虫 病消除成果。.
Keywords: Guangxi Zhuang Autonomous Region; Oncomelania hupensis; Schistosomiasis; Surveillance.