Key Laboratory of Monitoring and Estimate for Environment and Disaster of Hubei Province, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, People's Republic of China.
Hubei Center for Disease Control and Prevention, Hubei Provincial Academy of Preventive Medicine, Wuhan, People's Republic of China.
Parasit Vectors. 2020 Aug 5;13(1):397. doi: 10.1186/s13071-020-04273-1.
Schistosomiasis remains prevalent in Africa, Asia and South America with an estimated burden of 1.9 million disability-adjusted life years in 2016. Targeting snails as a key to success for schistosomiasis control has been widely approved, but the long-term quantitative effects of interventions on snail control that would inform and improve future control programmes are unclear. Over the last six decades, schistosomiasis in China had been brought largely under control, and snail control as supplementary methods or part of integrated multisectoral approaches in different historical periods has played an essential role.
Ecological environment factors, prevalence and control data on Oncomelania hupensis between 1985 and 2015 at 5-year intervals in Qianjiang city, China, were collected. A multilevel growth model approach was used to examine the long-term effects of ecological environmental changes and mollusciciding on snail-infested area (SIA) and living snail density (LSD) during the 30 years.
The variation of SIA was 68.4% in spatial distribution, while the variation of LSD was 68.4% in temporal distribution. Continuous mollusciciding could result in significant LSD reduction, but may not lead to significant SIA reduction. The normalized difference vegetation index (NDVI), patch size coefficient of variation (PSCoV) and mean patch size (MPS) reduction, slightly due to eco-environmental changes decreased SIA, while mean perimeter-area ratio (MPAR) and dry farm-land proportion (DFLP) reduction might increase SIA. Only NDVI and MPAR reduction led to a lower LSD.
Mollusciciding was more effective in reducing snail density, but it is not easy to eliminate snails completely. Environmental modifications could completely change the snail breeding environment and reduce its infestation area. Due to difficulty of scaling-up the current environmental modifications in waterway network regions, more effective snail control methods are needed. The experience in China could thereby provide guidance for other schistosomiasis endemic areas with a high snail prevalence.
2016 年，估计有 190 万残疾调整生命年的负担，血吸虫病在非洲、亚洲和南美洲仍然流行。将钉螺作为成功控制血吸虫病的关键目标已得到广泛认可，但干预措施对钉螺控制的长期定量影响尚不清楚，这些影响将为未来的控制规划提供信息并加以改进。在过去的六十年中，中国的血吸虫病已得到基本控制，在不同的历史时期，钉螺控制作为补充方法或综合多部门方法的一部分发挥了重要作用。
收集了中国潜江市 1985 年至 2015 年每 5 年一次的地理环境因素、感染性钉螺面积（SIA）和活螺密度（LSD）的流行率和控制数据。采用多层次增长模型方法，考察了 30 年来生态环境变化和药物灭螺对 SIA 和 LSD 的长期影响。
SIA 在空间分布上的变异性为 68.4%，而 LSD 在时间分布上的变异性为 68.4%。连续药物灭螺可显著降低 LSD，但不一定导致 SIA 显著降低。归一化植被指数（NDVI）、斑块大小变异系数（PSCoV）和平均斑块大小（MPS）的降低，主要是由于生态环境的变化，导致 SIA 减少，而平均周长-面积比（MPAR）和旱地比例（DFLP）的降低可能会增加 SIA。只有 NDVI 和 MPAR 的降低会导致 LSD 降低。
药物灭螺在降低螺密度方面更为有效，但难以完全消灭钉螺。环境改良可以彻底改变钉螺的繁殖环境，减少其感染面积。由于在水系网络地区扩大环境改良规模存在困难，需要更有效的钉螺控制方法。中国的经验可为其他高流行区的血吸虫病提供指导。
