Magero Victor O, Kisara Sammy, Suleman Mbaruk A, Wade Christopher M
School of Life Sciences, University of Nottingham, Nottingham NG7 2RD, UK.
Tropical and Infectious Diseases Department, Institute of Primate Research, P.O. Box 24481, Karen - 00502 Nairobi, Kenya.
Trans R Soc Trop Med Hyg. 2025 Mar 7;119(3):253-265. doi: 10.1093/trstmh/trae115.
There is a need for current and more detailed information on the distribution of Biomphalaria pfeifferi snails in East Africa's river systems. B. pfeifferi is arguably the most important snail intermediate host in the transmission of schistosomiasis, a disease ranked second to malaria in terms of tropical diseases of public health importance.
We assessed the occurrence and geographical distribution of B. pfeifferi snails in Kenya, Uganda and Tanzania. Maximum entropy modelling was used to predict the potential distribution of B. pfeifferi snails and malacological surveys were conducted guided by MaxEnt predictions and information from previous studies. Malacological surveys were conducted at a total of 172 sites, including streams, rivers, dams, irrigation schemes and springs over a 3-y period from 2018 to 2020, with geospatial, ecological and physicochemical information recorded for each site.
B. pfeifferi snails were found at 23 of the 172 sites and inhabited a variety of habitat types. Of the 23 sites where B. pfeifferi snails were found, 15 (65.2%) were streams, 3 rivers (13.04%), 2 dams (8.7%), 2 springs (8.7%) and 1 an irrigation scheme (4.35%). B. pfeifferi abundance showed a significant positive correlation with increasing water temperature and decreasing water depth. In Kenya, B. pfeifferi snails were found around the Lake Victoria basin, the Mwea irrigation scheme and in parts of the former Eastern Province of Kenya. In Uganda, B. pfeifferi snails were found in Jinja District, Ntoroko District and Soroti District. In Tanzania, B. pfeifferi snails were found in the Iringa, Tabora and Kigoma Regions. We observed moderate to high prevalence of Schistosoma mansoni infection, with S. mansoni-infected snails found at 11 of 23 sites and with an average prevalence of 24.9% at infected sites. In Kenya, S. mansoni-infected snails were found in the Lake Victoria basin (22.5% prevalence at infected sites) and the former Eastern Province (13.5% prevalence at infected sites). In Uganda, infected snails were found in Ntoroko District (100% infected) and Soroti District (20% infected). In Tanzania, infected snails were found in the Kigoma Region, with a prevalence of 10% at the infected site.
This information on the distribution of B. pfeifferi snails and S. mansoni infection in East Africa's river systems can aid in developing better prevention and control strategies for human schistosomiasis. Regular surveys of the river systems for snail intermediate hosts followed by molecular detection of schistosome infection could form a basis for the development of a prompt and cost-effective surveillance system for schistosomiasis in the region.
需要有关东非河流系统中费氏双脐螺分布的最新且更详细的信息。费氏双脐螺可以说是血吸虫病传播中最重要的中间宿主螺类，血吸虫病是在具有公共卫生重要性的热带疾病中仅次于疟疾的疾病。
我们评估了肯尼亚、乌干达和坦桑尼亚费氏双脐螺的出现情况和地理分布。利用最大熵模型预测费氏双脐螺的潜在分布，并在前人研究信息及最大熵预测的指导下开展贝类学调查。在2018年至2020年的3年时间里，共在172个地点进行了贝类学调查，这些地点包括溪流、河流、水坝、灌溉设施和泉水，记录了每个地点的地理空间、生态和理化信息。
在172个地点中的23个发现了费氏双脐螺，它们栖息于多种生境类型。在发现费氏双脐螺的23个地点中，15个（65.2%）是溪流，3条河流（13.04%），2座水坝（8.7%），2处泉水（8.7%）和1处灌溉设施（4.35%）。费氏双脐螺的丰度与水温升高和水深降低呈显著正相关。在肯尼亚，费氏双脐螺出现在维多利亚湖流域、姆韦亚灌溉区以及肯尼亚前东部省的部分地区。在乌干达，费氏双脐螺出现在金贾区、恩托罗科区和索罗蒂区。在坦桑尼亚，费氏双脐螺出现在伊林加、塔博拉和基戈马地区。我们观察到曼氏血吸虫感染的患病率为中度到高度，在23个地点中的11个发现了感染曼氏血吸虫的螺，感染地点的平均患病率为24.9%。在肯尼亚，感染曼氏血吸虫的螺出现在维多利亚湖流域（感染地点患病率为22.5%）和前东部省（感染地点患病率为13.
