Oduor Noel A, Kariuki Daniel W, Mkoji Gerald M, Oraro Polycup O, Laidemitt Martina R, Steinauer Michelle L, Loker Eric S, Agola Eric L
Biochemistry Department, School of Biomedical Sciences, Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya.
Center for Biotechnology Research and Development, Kenya Medical Research Institute, Nairobi, Kenya.
Parasit Vectors. 2025 Jun 21;18(1):235. doi: 10.1186/s13071-025-06881-1.
Biomphalaria pfeifferi, a predominantly self-fertilizing freshwater snail, is the world's most important intermediate host for Schistosoma mansoni, one of the causative agents of schistosomiasis, a neglected tropical disease affecting millions of people in sub-Saharan Africa. We sought to determine whether we could identify distinct and persistent lineages of B. pfeifferi within a natural stream habitat in western Kenya, indicative of their asexual descent. We also sought to determine whether infections by S. mansoni or other trematodes were associated with particular lineages.
Utilizing 14 microsatellite markers in a multiplex polymerase chain reaction (PCR) format, we genotyped 502 B. pfeifferi collected in six bimonthly (every other month) sampling times from the same locality in a single habitat (Asao Stream, western Kenya). Snails were isolated and screened for infection with S. mansoni and other trematodes using the shedding method followed by microscopical examination of any cercariae found.
We identified 26 multilocus genotypes (MLGs), that were present at two or more sampling times. Four MLGs persisted across the entire 10-month sampling period, one of which was represented by 17 individuals. These persistent lineages harbored a variety of trematode species, with S. mansoni being the most common. The persistent MLGs were more likely to have trematode infections than those found only at a single sampling time. Low genetic differentiation was observed between November and March (fixation index among subpopulations [F] = 0.019; p = < 0.05). The highest genetic differentiation was observed between July and March (F = 0.372; p = < 0.001). Analysis of molecular variance (AMOVA) showed higher variation among individuals within sampling times (58%) than within individuals (33%), and a smaller variation (8%) was found among sampling times.
By identifying the presence of persistent MLGs and their associations with trematode transmission, this study highlights the importance of considering B. pfeifferi MLGs, some of which could be resistant to infection, when developing strategies to control schistosomiasis transmission within Asao Stream and similar ecosystems across sub-Saharan Africa.
费氏扁卷螺是一种主要进行自体受精的淡水螺，是世界上曼氏血吸虫最重要的中间宿主。曼氏血吸虫是血吸虫病的致病因子之一，这是一种被忽视的热带疾病，影响着撒哈拉以南非洲数百万人口。我们试图确定在肯尼亚西部的一个天然溪流栖息地内，是否能识别出费氏扁卷螺不同且持久的谱系，这表明它们是无性繁殖的后代。我们还试图确定曼氏血吸虫或其他吸虫的感染是否与特定谱系相关。
我们利用14个微卫星标记以多重聚合酶链反应（PCR）形式，对在肯尼亚西部单一栖息地（阿绍溪）同一地点每两个月（每隔一个月）采样一次、共六个采样时间收集的502只费氏扁卷螺进行基因分型。将蜗牛分离出来，采用逸出法进行曼氏血吸虫和其他吸虫感染筛查，随后对发现的任何尾蚴进行显微镜检查。
我们识别出26种多位点基因型（MLGs），这些基因型在两个或更多采样时间出现。有4种MLGs在整个为期10个月的采样期内持续存在，其中一种由17个个体代表。这些持久的谱系携带着多种吸虫物种，其中曼氏血吸虫最为常见。与仅在单个采样时间发现的MLGs相比，持久的MLGs更有可能感染吸虫。11月和3月之间观察到低遗传分化（亚种群间固定指数[F]=0.019；p<0.05）。7月和3月之间观察到最高遗传分化（F=0.372；p<0.001）。分子方差分析（AMOVA）显示，采样时间内个体间的变异（58%）高于个体内变异（33%），采样时间之间的变异较小（8%）。
通过识别持久MLGs的存在及其与吸虫传播的关联，本研究强调了在制定控制阿绍溪及撒哈拉以南非洲类似生态系统内血吸虫病传播的策略时，考虑费氏扁卷螺MLGs的重要性，其中一些MLGs可能对感染具有抗性。
