Decelerating Spread of West Nile Virus by Percolation in a Heterogeneous Urban Landscape

Vector-borne diseases are emerging and re-emerging in urban environments throughout the world, presenting an increasing challenge to human health and a major obstacle to development. Currently, more than half of the global population is concentrated in urban environments, which are highly heterogeneous in the extent, degree, and distribution of environmental modifications. Because the prevalence of vector-borne pathogens is so closely coupled to the ecologies of vector and host species, this heterogeneity has the potential to significantly alter the dynamical systems through which pathogens propagate, and also thereby affect the epidemiological patterns of disease at multiple spatial scales. One such pattern is the speed of spread. Whereas standard models hold that pathogens spread as waves with constant or increasing speed, we hypothesized that heterogeneity in urban environments would cause decelerating travelling waves in incipient epidemics. To test this hypothesis, we analysed data on the spread of West Nile virus (WNV) in New York City (NYC), the 1999 epicentre of the North American pandemic, during annual epizootics from 2000–2008. These data show evidence of deceleration in all years studied, consistent with our hypothesis. To further explain these patterns, we developed a spatial model for vector-borne disease transmission in a heterogeneous environment. An emergent property of this model is that deceleration occurs only in the vicinity of a critical point. Geostatistical analysis suggests that NYC may be on the edge of this criticality. Together, these analyses provide the first evidence for the endogenous generation of decelerating travelling waves in an emerging infectious disease. Since the reported deceleration results from the heterogeneity of the environment through which the pathogen percolates, our findings suggest that targeting control at key sites could efficiently prevent pathogen spread to remote susceptible areas or even halt epidemics

Prospective Comparison Between Shotgun Metagenomics and Sanger Sequencing of the 16S rRNA Gene for the Etiological Diagnosis of Infections

International audienceBacteriological diagnosis is traditionally based on culture. However, this method may be limited by the difficulty of cultivating certain species or by prior exposure to antibiotics, which justifies the resort to molecular methods, such as Sanger sequencing of the 16S rRNA gene (Sanger 16S). Recently, shotgun metagenomics (SMg) has emerged as a powerful tool to identify a wide range of pathogenic microorganisms in numerous clinical contexts. In this study, we compared the performance of SMg to Sanger 16S for bacterial detection and identification. All patients’ samples for which Sanger 16S was requested between November 2019 and April 2020 in our institution were prospectively included. The corresponding samples were tested with a commercial 16S semi-automated method and a semi-quantitative pan-microorganism DNA- and RNA-based SMg method. Sixty-seven samples from 64 patients were analyzed. Overall, SMg was able to identify a bacterial etiology in 46.3% of cases (31/67) vs. 38.8% (26/67) with Sanger 16S. This difference reached significance when only the results obtained at the species level were compared (28/67 vs. 13/67). This study provides one of the first evidence of a significantly better performance of SMg than Sanger 16S for bacterial detection at the species level in patients with infectious diseases for whom culture-based methods have failed. This technology has the potential to replace Sanger 16S in routine practice for infectious disease diagnosis

Sunscreens in Coastal Ecosystems. Chapter:Fate and behavior of uv filters in the marine environment

UV filters are released into the coastal areas by a combination of different sources, including wastewater discharges and direct input related to recreational activities. To fully understand the risks associated with the occurrence of UV filters in the marine environment, better knowledge on their distribution and environmental behavior is required. So far, concentrations of several parts per trillion have been reported in different marine settings from touristic areas. Temporal variations in levels for organic UV filters have been associated with beach use, whereas for inorganic UV filters a preferential accumulation in the surface microlayer was observed. The latter are often released as nanoparticles, which have a tendency to form aggregates and precipitate. Due to their relatively high hydrophobicity, organic UV filters can also end up in the seafloor. Although sediments are not so frequently monitored at seawater, higher UV-filter levels (a few ng g−1) are usually found. Regarding their reactivity in the marine environment, the elucidation of degradation pathways and kinetics is still mostly unknown, although photochemical degradation seems to be a major transformation route for most organic UV filters. Regarding inorganic UV filters, their nanoparticles are subjected to weathering or aging and have also tendency to generate free radicals such as hydrogen peroxide under solar irradiatio