Risk & Policy Analysts (United Kingdom)

In areas of high infection prevalence, effective control of schistosomiasis – one of the most important Neglected Tropical Diseases – requires supplementing medical treatment with interventions targeted at the environmental reservoir of disease. In addition to provision of clean water, reliable sanitation, and molluscicide use to control the obligate intermediate host snail, top-down biological control of parasite-competent snails has recently gained increasing interest in the scientific community. However, evidence that natural predators can effectively reduce snail abundance and, ultimately, transmission risk to vulnerable human populations remains limited. In this study, we used a Before-After-Control-Intervention (BACI) design implemented in seven lakeside areas, including three intervention areas and four control areas, on the southern shores of Lake Victoria (Tanzania) in 2019–2023. We tested whether the restoration of African catfish, Clarias gariepinus, a native species of commercial value, could reduce both the abundance of Biomphalaria snails (intermediate hosts of Schistosoma mansoni) and infection intensity in school age children (SAC). Where catfish were restored, mean site-level snail counts declined by 57% (95% CI: 29.4%, 74.3%). At primary schools located within each area, SAC infection intensity (mean parasite egg count in stool samples) also decreased significantly by 55% (95% CI: 26%, 73%). This study shows that natural predators of host snails have the potential for schistosomiasis control. Scaling up to a lake-wide approach will require systemic intervention, with snail host control contributing to a broader framework for schistosomiasis management.

For many species, estimating density is challenging, but it is important for conservation planning and understanding the functional role of species. Bats play key ecological roles, yet little is known about their free‐ranging density. We used a long‐term banding study of four species caught in an extensively forested climate refuge and spatial capture–recapture models (SCR) to estimate density and its change over time. Between 1999 and 2020, there were 3671 captures of four bat species, which were all edge‐space foragers. Recaptures represented 16% (n = 587) of all captures, of which 89 were between‐trap‐cluster movements. Closed spatial mark–recapture models estimated plausible densities that varied with elevation. Preferred elevations differed between species, with density averaging 0.63 ha−1 for Vespadelus darlingtoni (high elevation), 0.43 ha−1 for V. pumilus (low elevation), 0.19 ha−1 for Chalinolobus morio (high elevation), and 0.08 ha−1 for V. regulus (high elevation). Overall, densities were higher than most previous published estimates for bats. Forest disturbance history (past timber harvesting) had no detectable effect on density. Density also varied substantially across years, and although annual maximum temperature and rainfall were not supported in models, some time periods showed an apparent relationship between density and annual rainfall (+ve) and/or annual maximum temperature (−ve). The most notable change was an increase in the density of V. pumilus after 2013, which tracked an increase in annual temperature at the site, reflecting a warming climate. Bat densities in forests outside of climate refugia are likely to be more sensitive to climate change, but more studies are needed in different habitats and continents and outside climate refugia to place the densities we estimated into a broader context.

The water footprint concept has been used by agricultural, commercial, and industrial water users to measure and report their water consumption, assess the magnitude of potential environmental impacts arising from this consumption, and identify opportunities for risk mitigation strategies that promote sustainable water use. However, water and wastewater utilities have not studied and documented the application of this concept in the same manner that other industries have. This article summarizes the growing body of information on the water footprint concept and the opportunities for integrating the concept into water utility planning efforts as a broader means of achieving and maintaining sustainable communities. The application of the water footprint concept for capital improvement planning, water resources decision‐making, operational benchmarking, and stakeholder communications is discussed, as is how the methodology, developed by the International Organization for Standardization, can be used for a water utility.