A groundbreaking study recently published in the esteemed journal One Earth reveals an urgent need to unify and integrate risk assessments related to zoonotic and vector-borne diseases, especially in the escalating context of climate change. The research, spearheaded by the Nucleus of Analysis and Synthesis of Nature-Based Solutions (BIOTA Synthesis) at the University of São Paulo, Brazil, underscores that current fragmentation in evaluating disease transmission risks hinders the development of comprehensive public health policies and effective early warning systems. As environmental changes increasingly disrupt ecosystems, such unified approaches could be pivotal in anticipating and mitigating outbreaks.
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
