Background: Schistosomiasis, due to S. mansoni, is prevalent in Rwanda. However, there is a paucity of information related to the abundance, species, distribution, and infectivity of Schistosoma intermediate host snails. Methods: Snails were collected from 71 sites, including lakeshores and wetlands. Snails obtained were morphologically identified, and cercariae were shed using standard procedures. Cercariae were molecularly characterized using PCR. GPS coordinates were used to generate geospatial maps of snail distribution that were overlaid with geospatial distribution of schistosomiasis among pre-school children in the same areas. Results: Overall, 3653 snails were morphologically classified as Bulinus spp. and 1449 as Biomphalaria spp. A total of 306 snails shed cercariae, 130 of which were confirmed as S. mansoni cercaria by PCR. There was no significant difference in the proportion of S. mansoni cercariae in wetlands compared to lakeshores. Conclusion: Rwandan water bodies harbor an important number of snails that shed S. mansoni cercariae. Furthermore, a strong spatial correlation was observed between the distribution of schistosomiasis in children and the spatial distribution of snail infectivity with S. mansoni. The presence of Bulinus spp. Suggests a potential risk of S. haematobium, although molecular analysis did not show any current transmission of this parasite.

The loss of forest cover across landscapes poses significant environmental challenges, particularly within biodiversity hotspots. In Rwanda, the Congo–Nile Crest is one such critical hotspot, rich in biodiversity and situated between the two largest basins in Africa, the Congo and Nile basins. However, limited knowledge is currently available on the dynamics of forest cover and tree density within this region, hindering informed decision-making for sustainable forest and tree management. Therefore, this study aims to assess forest cover and tree density changes between 2009 and 2019 using high-resolution aerial imagery and advanced geospatial analysis. The findings reveal a 7% increase in overall forest cover within the studied period, with 43% of the forest remaining stable, and a minimal loss of about 2.1% primarily from plantations. Tree density outside natural forest showed a positive trend, with an average increase of about 23 trees per hectare, and a strong positive correlation (r = 0.74) between 2009 and 2019, indicating a consistent spatial distribution. Areas with higher tree density in 2009 gained additional trees, as indicated by a regression slope of 1.05, suggesting continued restoration efforts. However, nearly 18% of sites experienced a decline in tree density, indicating uneven recovery and localized degradation. These findings highlight the success of Rwanda’s ambitions toward increasing forest cover, but also stress the need for targeted interventions in areas that faced decline and those with less tree cover. This study provides valuable insights for future forest management initiatives and emphasizes the importance of forest cover and tree density in biodiversity conservation.

Pharmaceuticals, pesticides, and polyphenols are increasingly detected in aquatic environments, impacting water quality and aquatic life. This study screened these contaminants in Rwanda’s Nyabugogo River, analysing 45 water samples from rural, peri-urban, and urban areas using solid-phase extraction and LC–MS/MS. Fifty-seven pharmaceuticals, five pesticides, and four polyphenols were quantified, with the highest average concentrations of albendazole (960 ng/L), metalaxyl (70 ng/L), and caffeic acid (49 ng/L). Pharmaceutical levels were significantly higher in urban areas, reflecting inadequate sanitation and wastewater management in Kigali, while pesticide and polyphenol concentrations varied across different types of land use, influenced by agricultural and urban discharges. Temporal sampling revealed significant within-day concentration fluctuations but consistent day-to-day levels, indicating persistent contamination sources. These findings provide essential baseline data for monitoring organic pollutants and informing strategies to mitigate contamination in urban river systems.