Department of Biological Sciences, University of Zimbabwe, Harare, Zimbabwe.
Laboratory of Molecular Cell Biology, KU Leuven, Leuven, Belgium.
Parasitol Int. 2024 Apr;99:102830. doi: 10.1016/j.parint.2023.102830. Epub 2023 Nov 26.
The construction of Lake Kariba brought about a rise in the incidence of schistosomiasis in its surrounding towns of Kariba (Zimbabwe) and Siavonga (Zambia). After extensive control programs in Kariba, schistosomiasis prevalence dropped significantly. The objective of this study was to revisit the same localities sampled by Chimbari et al. (2003), and provide an update on the snail community and prevalence of trematodes in the Northern shore of Lake Kariba while focusing on planorbid species.
Monthly sampling of snails at 16 sites along the Northern shoreline of Lake Kariba, near Kariba town, was undertaken for one year. Minimum one specimen per morphotype was identified using molecular barcoding (sequencing a fragment of cytochrome c oxidase I subunit (COI)). The infection status of snails was assessed by Rapid Diagnostic PCRs (RD-PCR), and trematode infections were genotyped by sequencing COI and 18S rDNA markers.
We collected and identified seven snail species: Bulinus truncatus, Bulinus forskalii, Gyraulus sp., Physella acuta, Bellamya sp., Radix affinis plicatula and Pseudosuccinea columella. Physella acuta was the most abundant snail species (comprising 56.95% of the total snail count) and present at all sites. The B. truncatus population was found to be infected with the stomach fluke Carmyerius cruciformis, a Petasiger sp. and a trematode species belonging to the family Notocotylidae. No Schistosoma sp. infections were detected in our collected snail specimens.
We report B. truncatus as an intermediate snail host for Carmyerius cruciformis, and the presence of three non-schistosome trematode species that have not been reported in Lake Kariba before. Furthermore, we detect a possible shift in the snail community when compared to the report by Chimbari et al. (2003): this is the first record of Gyraulus sp. in Lake Kariba, and we did not observe the previously reported B. pfeifferi, B. globosus and Radix natalensis. Although this shift in snail communities might have contributed to the absence of Schistosoma spp. detection in this study, further monitoring of final and intermediate hosts across the Kariba basin is essential to prove a decrease of schistosomiasis in the area.
卡里巴湖的建设导致其周边城镇卡里巴（津巴布韦）和西凡加（赞比亚）的血吸虫病发病率上升。在卡里巴广泛开展防治规划后，血吸虫病的流行率显著下降。本研究的目的是重新调查 Chimbari 等人（2003 年）采样的同一地点，并提供卡里巴湖北岸的蜗牛群落和吸虫流行情况的最新信息，重点关注 Planorbidae 物种。
在卡里巴镇附近的卡里巴湖北岸 16 个地点进行为期一年的每月蜗牛采样。使用分子条形码（COI 亚单位（COI）的一段序列）对每个形态型的最小一个样本进行鉴定。通过快速诊断聚合酶链反应（RD-PCR）评估蜗牛的感染状况，并通过测序 COI 和 18S rDNA 标记物对吸虫感染进行基因分型。
我们共收集和鉴定了 7 种蜗牛：Bulinus truncatus、Bulinus forskalii、Gyraulus sp.、Physella acuta、Bellamya sp.、Radix affinis plicatula 和 Pseudosuccinea columella。Physella acuta 是最丰富的蜗牛物种（占总蜗牛数量的 56.95%），存在于所有地点。发现 B. truncatus 种群感染了胃吸虫 Carmyerius cruciformis、Petasiger sp. 和一种以前未在卡里巴湖报道的 Notocotylidae 科吸虫。在我们收集的蜗牛标本中未检测到 Schistosoma sp. 感染。
我们报告 B. truncatus 是 Carmyerius cruciformis 的中间宿主，并且还发现了三种以前未在卡里巴湖报道的非血吸虫吸虫。此外，与 Chimbari 等人（2003 年）的报告相比，我们检测到蜗牛群落可能发生了变化：这是 Gyraulus sp. 在卡里巴湖的首次记录，我们没有观察到以前报道的 B. pfeifferi、B. globosus 和 Radix natalensis。尽管这种蜗牛群落的变化可能导致本研究中未检测到 Schistosoma spp.，但仍需要对卡里巴流域的最终和中间宿主进行进一步监测，以证明该地区血吸虫病的减少。
