Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.
Wellcome Centre for Integrative Parasitology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.
Parasit Vectors. 2022 Jan 6;15(1):15. doi: 10.1186/s13071-021-05121-6.
Annual mass drug administration with praziquantel has reduced schistosomiasis transmission in some highly endemic areas, but areas with persistent high endemicity have been identified across sub-Saharan Africa, including Uganda. In these areas many children are rapidly reinfected post treatment, while some children remain uninfected or have low-intensity infections. The aim of this mixed-methods study was to better understand variation in water contact locations, behaviours and infection risk in school-aged children within an area with persistent high endemicity to inform additional control efforts.
Data were collected in Bugoto, Mayuge District, Uganda. Two risk groups were identified from a longitudinal cohort, and eight children with no/low-intensity infections and eight children with reinfections were recruited. Individual structured day-long observations with a focus on water contact were conducted over two periods in 2018. In all identified water contact sites, four snail surveys were conducted quarterly over 1 year. All observed Biomphalaria snails were collected, counted and monitored in the laboratory for Schistosoma mansoni cercarial shedding for 3 weeks.
Children came into contact with water for a range of purposes, either directly at the water sources or by coming into contact with water collected previously. Although some water contact practices were similar between the risk groups, only children with reinfection were observed fetching water for commercial purposes and swimming in water sources; this latter group of children also came into contact with water at a larger variety and number of sites compared to children with no/low-intensity infection. Households with children with no/low-intensity infections collected rainwater more often. Water contact was observed at 10 sites throughout the study, and a total of 9457 Biomphalaria snails were collected from these sites over four sampling periods. Four lake sites had a significantly higher Biomphalaria choanomphala abundance, and reinfected children came into contact with water at these sites more often than children with no/low-intensity infections. While only six snails shed cercariae, four were from sites only contacted by reinfected children.
Children with reinfection have more high-risk water contact behaviours and accessed water sites with higher B. choanomphala abundance, demonstrating that specific water contact behaviours interact with environmental features to explain variation in risk within areas with persistent high endemicity. Targeted behaviour change, vector control and safe water supplies could reduce reinfection in school-aged children in these settings.
在一些高度流行地区，每年进行大规模的药物治疗已降低了血吸虫病的传播，但在撒哈拉以南非洲，包括乌干达在内，仍存在持续高度流行的地区。在这些地区，许多儿童在治疗后很快再次感染，而有些儿童则未感染或感染程度较低。本项混合方法研究旨在更好地了解高流行地区学龄儿童的水接触地点、行为和感染风险的变化，以为进一步的控制工作提供信息。
数据收集于乌干达马尤盖区的布戈托。从一个纵向队列中确定了两个风险组，并招募了 8 名无/低强度感染的儿童和 8 名再感染的儿童。2018 年分两个阶段进行了为期一天的个人结构化观察，重点是水接触。在一年内，每季度对所有确定的水接触点进行了 4 次钉螺调查。所有观察到的有尾两栖螺均被收集、计数，并在实验室中监测曼氏血吸虫尾蚴脱落 3 周。
儿童出于各种目的接触水，要么直接在水源处，要么接触先前收集的水。尽管两组风险儿童的一些水接触行为相似，但只有再感染的儿童才被观察到从事商业取水和在水源中游泳；与无/低强度感染的儿童相比，后一组儿童还接触到更多不同类型和数量的水接触点。无/低强度感染儿童的家庭更经常收集雨水。在整个研究过程中观察到 10 个地点的水接触，在四个采样期内共从这些地点采集了 9457 只有尾两栖螺。四个湖泊地点有更高的 B. choanomphala 丰度，再感染的儿童比无/低强度感染的儿童更经常接触这些地点的水。虽然只有 6 只螺产生了尾蚴，但其中 4 只来自仅被再感染儿童接触的地点。
再感染儿童有更多的高风险水接触行为，并接触到有更高 B. choanomphala 丰度的水接触点，这表明特定的水接触行为与环境特征相互作用，可解释高流行地区内风险的变化。在这些环境中，有针对性的行为改变、病媒控制和安全供水可以减少学龄儿童的再感染。
