The research team conducted an exhaustive meta-analysis of 312 studies examining the transmission risks of 39 different pathogens and diseases, all transmitted either by infected animals or by vectors such as mosquitoes. Strikingly, only 7.4% of these studies thoroughly accounted for all three critical components of risk: hazard, exposure, and vulnerability. This reveals a significant gap in how risk is scientifically conceptualized and operationalized, with many studies focusing narrowly on a single dimension, such as vector abundance, thereby limiting the reliability of models that inform public health decisions.

In technical terms, “hazard” refers to the presence or prevalence of zoonotic hosts, vectors, or reservoirs that harbor pathogens capable of infection. “Exposure” is the probability that humans will come into contact with these hazards, modulated by behavioral, ecological, and social variables. “Vulnerability” further incorporates the likelihood that, once exposed, individuals or groups will be infected, reflecting biological susceptibilities or other risk amplifiers. The researchers emphasize that it is the intersection of these three factors that constitutes the true risk landscape, a complexity frequently overlooked in isolated assessments.

Raquel Carvalho, the study’s lead author and a researcher at BIOTA Synthesis, highlights the lack of standardization in methodologies as a fundamental obstacle. For instance, a study assessing dengue risk might solely measure mosquito abundance, while another might focus on human exposure patterns such as outdoor activity frequency. Such inconsistencies undermine the predictive power of models and consequently impair strategic efforts for early detection and localized interventions. This heterogeneity in risk assessment frameworks leads to divergent and sometimes contradictory policy recommendations.

The study’s findings carry profound implications for spatial planning and resource allocation in public health. Overlooking any component of the risk triad—hazard, exposure, vulnerability—not only skews risk maps but can also foster misdirected management strategies. For example, prioritizing insecticide applications purely based on vector presence without considering human exposure patterns may waste resources and fail to curb transmission effectively. Conversely, neglecting vulnerability factors may leave at-risk populations dangerously exposed despite apparent low hazard levels.

The research team also played a pivotal role in informing the recently proposed State Plan for Climate Adaptation and Resilience (PEARC) in São Paulo, which integrates these refined concepts of risk assessment into its framework. PEARC’s nuanced delineation between hazard, exposure, and vulnerability forms a scientific cornerstone for climate adaptation strategies, aiming to mitigate the compounded threat of environmental change on zoonotic and vector-borne diseases. This work underscores the intersectionality of ecological and social dimensions in managing climate-related health risks.

One compelling example highlighted is the differential risk profiles of dengue compared to hantavirus infections. Dengue, transmitted by Aedes aegypti mosquitoes, correlates strongly with high human population density and anthropogenic water storage practices that facilitate breeding. Here, exposure and vulnerability are heightened, necessitating targeted vector control and public education campaigns. In contrast, hantavirus presence in wild rodent populations poses a lower risk in sparsely populated rural areas due to limited human contact, illustrating why detection of pathogens alone should not be equated with elevated transmission danger.

The article calls for international research realignment to bolster efforts in tropical regions, where zoonotic and vector-borne diseases present heightened challenges due to biodiversity richness and climate sensitivity. The authors advocate for dedicated funding channels and enhanced international collaboration aimed at standardizing risk methodologies and expanding surveillance capacity. Such cooperation is deemed critical to preemptively address emerging infections aggravated by shifting environmental conditions.

Another vital recommendation pertains to improving the surveillance infrastructure, including laboratory networks for diagnosing zoonoses and vector-borne infections. The current inadequacy in wildlife pathogen monitoring represents a significant blind spot, as animal hosts serve as reservoirs that can spill over to humans. Enhancing diagnostic capabilities and data sharing frameworks would facilitate timely identification of outbreak precursors, thus enabling more agile public health responses.

The study further highlights the intertwined relationship between water security and vector-borne diseases. Erratic or inefficient water distribution often compels communities to store water unsafely, inadvertently creating breeding grounds for mosquitoes. Rationalizing water management is presented as a key preventive measure that addresses one of the root environmental drivers of disease proliferation. Moreover, it aligns with broader sustainability goals and climate adaptation policies, reinforcing the multi-sectoral nature of effective disease control.

Carvalho’s work also exemplifies the value of interdisciplinary and international training, having involved an internship at the University of Glasgow, Scotland. This global perspective enriches the research approach by incorporating diverse scientific paradigms and strengthening networks for knowledge exchange. Presently, Carvalho continues her investigations as a professor in the Department of Zoology at the Institute of Biosciences, University of São Paulo, contributing to the translational potential of this integrative framework.

Ultimately, this study shines a powerful spotlight on the necessity of holistic, standardized approaches to assessing and managing the risks posed by zoonotic and vector-borne diseases in an era of profound environmental upheaval. By bridging ecological, behavioral, and social dimensions through integrative methodologies, policymakers and scientists can forge more effective, adaptive, and equitable strategies. In doing so, they confront not only the immediate biological threats but also the broader challenges of global change.

Subject of Research: Risk assessment of zoonotic and vector-borne diseases in relation to environmental change and climate impacts

Article Title: Unpacking the risks of zoonotic and vector-borne pathogen transmission to humans in the context of environmental change

News Publication Date: 23-Jun-2025

Web References:

• Journal Article DOI: http://dx.doi.org/10.1016/j.oneear.2025.101348
• BIOTA Synthesis: https://biotasintese.iea.usp.br/
• São Paulo Research Foundation (FAPESP): https://www.fapesp.br/en

Keywords: Risk assessment, Disease outbreaks, Infectious diseases, Public policy, Zoonoses, Mosquitoes, Climate change effects

Central to the study is an expansive assessment of SARS-CoV-2 RNA levels detected in wastewater samples collected from arriving aircraft, which serve as concentrated catchments of diverse international populations. The researchers deftly demonstrated that viral fragments shed in passengers’ biological waste could be quantified and used to infer the prevalence of COVID-19 among travelers. This approach effectively transforms airplane wastewater into a sentinel surveillance tool, enabling health authorities to monitor potential introductions of new variants and emerging outbreaks before symptomatic cases surface in clinical settings.

The technical underpinnings of viral detection relied on advanced reverse transcription-quantitative polymerase chain reaction (RT-qPCR) targeting specific regions of the SARS-CoV-2 genome. By optimizing sample concentration methods and accounting for environmental RNA degradation factors inherent to wastewater matrices, the team achieved sensitive and reproducible viral quantification. These methodological refinements are critical, considering the complex composition of aircraft wastewater, where chemical disinfectants, varying temperatures, and fluctuating pH levels pose analytical challenges.

Scaling beyond individual flights, the investigation incorporated citywide wastewater sampling from urban sewage treatment plants serving large populations. Here, the surveillance leveraged composite sampling strategies that integrate fluid aliquots over time to produce representative viral load metrics. By correlating viral RNA concentrations with temporally aligned epidemiological case reports, the study validated the use of wastewater viral signals as proxies for community-level infection dynamics, including surges associated with variant-driven transmission waves.

An intriguing dimension of the research was the comparative analysis between localized aircraft sample data and aggregated city wastewater trends. This dual-level framework provided a rich temporal and spatial resolution, revealing how viral introductions via air travel could precede observable community spread. Such insights underscore the vital role of border and travel-related surveillance as a frontline defense metric that complements traditional contact tracing and diagnostic testing.

From a virological standpoint, the detection of SARS-CoV-2 RNA in wastewater does not equate to the presence of infectious virus particles but serves as an epidemiological marker. The study meticulously discusses the stability of viral RNA fragments in wastewater environments, supported by controlled laboratory experiments that delineate decay kinetics under different physicochemical conditions. This understanding enhances interpretation accuracy and supports the timing of sampling efforts to maximize epidemiological relevance.

Beyond methodological rigor, the multi-institutional effort highlights interdisciplinary collaboration, incorporating virologists, environmental engineers, epidemiologists, and data scientists. The integration of metagenomics and bioinformatics pipelines enabled the detection not only of SARS-CoV-2 presence but also of variant-specific genetic markers. This capability is especially significant given the ongoing emergence of novel variants with altered transmissibility and immune evasion properties.

Funding considerations and implementation logistics are thoughtfully addressed, emphasizing the cost-effectiveness of wastewater surveillance compared to mass individual testing, especially in settings where clinical testing resources may be constrained. The relative ease of sample collection and the non-invasiveness of WBE further promote its utility in diverse socioeconomic contexts, fostering equitable public health monitoring.

Ethical and privacy implications receive attention as well. Because wastewater data reflect aggregated population signals without individual identification, WBE circumvents many privacy challenges inherent in personal diagnostic data collection. Nevertheless, the researchers caution against overinterpretation of results at micro-scale resolutions that could inadvertently stigmatize smaller communities or institutionalized populations.

The temporal responsiveness of wastewater surveillance systems proved advantageous in detecting early surges of infection, often preceding clinical reporting by several days. This lead time could allow public health agencies to enact timely containment measures, such as targeted testing, quarantine protocols, or public advisories, thereby mitigating the public health impact.

Moreover, the article explores the potential expansion of such surveillance frameworks to other respiratory and enteric pathogens beyond SARS-CoV-2, envisioning a paradigm shift in infectious disease monitoring capacity. The adaptability of wastewater surveillance to various microbial targets heralds its establishment as a versatile epidemiological tool for future pandemics or endemic disease management.

Nevertheless, challenges persist. The heterogeneity in sewage systems, population behaviors affecting viral shedding, and environmental factors influencing viral RNA stability necessitate continuous refinement and local calibration of surveillance models. The authors advocate for standardized protocols and data-sharing platforms to enhance comparability and global responsiveness.

This research underscores the critical nexus of environmental science and infectious disease epidemiology, leveraging urban infrastructure for public health intelligence. The authors call for expanded collaboration at governmental and community levels to institutionalize wastewater surveillance in pandemic preparedness strategies, highlighting its potential to safeguard populations against rapid viral dissemination.

In concluding remarks, the study reiterates the value of integrating multi-scale viral surveillance—from aircraft wastewater to metropolitan sewage—in forming a comprehensive monitoring network. Such systems could act as early detectors, informing intervention timing and resource allocation while offering a cost-effective complement to individual testing efforts.

The work of Perez-Zabaleta and colleagues establishes an innovative foundation for transforming wastewater into a rich data source that can illuminate hidden viral transmission currents. It redefines surveillance frontiers, offering a potent means to track and curb SARS-CoV-2 spread amid evolving global health challenges, while simultaneously setting the stage for future pathogen detection innovations.

The research presented is a testament to the power of synergistic scientific endeavors that cross disciplinary boundaries and leverage technological advances to meet pressing epidemiological demands. As public health infrastructure adapts to a post-pandemic world, wastewater surveillance emerges as an indispensable component of resilient disease control architectures.

Ultimately, the findings presented in Nature Communications articulate an urgent call to scale wastewater-based monitoring approaches, harnessing their inherent strengths to preempt infectious outbreaks and safeguard population health in an increasingly interconnected world.

Subject of Research: Wastewater surveillance of SARS-CoV-2 from aircraft and citywide wastewater systems

Article Title: Wastewater surveillance of SARS-CoV-2 from aircraft to citywide monitoring

Article References:
Perez-Zabaleta, M., Berg, C., Latorre-Margalef, N. et al. Wastewater surveillance of SARS-CoV-2 from aircraft to citywide monitoring. Nat Commun 16, 5125 (2025). https://doi.org/10.1038/s41467-025-60490-1

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