Global climate change, ecological disruption, and increasing human mobility are converging to reshape infectious disease risk, as illustrated by recent hantavirus-associated cases linked to South American cruise routes.
Background
Recent reports of hantavirus-associated disease linked to cruise travel in South America have renewed international attention to the growing influence of climate and environmental change on zoonotic disease emergence. Although the World Health Organization (WHO) currently assesses the public health risk associated with this event as low, the outbreak serves as a timely reminder that zoonotic spillover is increasingly shaped by ecological disruption, climate variability, and human mobility [1]. While hantavirus disease remains concentrated in specific endemic regions, the ecological mechanisms underlying its transmission provide valuable insights into how climate and environmental change can influence zoonotic disease risks more broadly.
The emergence and spread of zoonotic diseases have become defining challenges of the twenty-first century. Approximately 60% of emerging infectious diseases in humans are zoonotic in origin, and most arise from wildlife reservoirs [2]. Historically, disease emergence was often viewed as an isolated biological event. However, growing evidence indicates that climate change, biodiversity loss, land-use change, agricultural expansion, and urbanisation are altering ecological systems in ways that facilitate pathogen transmission between animals and humans [3]. These changes influence wildlife host dynamics, vector ecology, pathogen persistence, and human exposure, creating new opportunities for disease emergence and spread [4].
The recent hantavirus event provides a timely example of this transition. While the outbreak itself remains limited, its occurrence within ecotourism and international travel networks illustrates how ecological disruption and global connectivity can intersect to amplify spillover opportunities and public health concerns. Importantly, such events highlight a critical weakness in current global preparedness systems: surveillance and response frameworks remain overwhelmingly reactive, focusing primarily on outbreak detection after human transmission has already occurred, rather than on anticipating ecological conditions associated with spillover emergence. As climate-related environmental change accelerates globally, understanding the ecological drivers of spillover is becoming increasingly important for global health preparedness.
Hantavirus and climate-sensitive spillover dynamics
Hantaviruses are rodent-borne pathogens maintained in wildlife reservoir species, particularly rodents within the Muridae and Cricetidae families. Human infection typically occurs through inhalation of aerosolised particles contaminated with rodent urine, saliva, or feces [1]. Unlike directly transmitted respiratory pathogens, hantaviruses primarily represent environmentally mediated zoonotic spillover events occurring at the human–animal–environment interface.
From an eco-epidemiological perspective, hantavirus transmission dynamics are tightly coupled to rodent population ecology. Climatic factors such as rainfall, temperature, humidity, and vegetation productivity strongly influence rodent abundance, breeding cycles, and habitat distribution. Increased rainfall can promote vegetation growth and food availability, leading to rapid rodent population expansion, whereas drought conditions may drive rodents closer to human settlements. Both scenarios can increase opportunities for zoonotic transmission [5]. Extreme weather events, including floods, droughts, and storms, may further alter host–pathogen interactions and increase spillover risk [4]. As climate change intensifies the frequency and severity of such events globally, the ecological systems governing zoonotic spillover are becoming increasingly unstable and unpredictable.
Beyond hantavirus: climate change and emerging disease ecology
These dynamics extend well beyond hantaviruses. Climate-sensitive mechanisms are increasingly recognised across a broad range of infectious diseases. For example, dengue fever continues to expand geographically in response to changing temperature and rainfall patterns, while flooding events contribute to outbreaks of leptospirosis and other environmentally mediated diseases [6, 7]. The emergence of Japanese encephalitis virus (JEV) in southeastern Australia since 2022 has further highlighted how environmental change, vector ecology, wildlife reservoirs, and animal hosts can converge to facilitate disease emergence [8]. Recent outbreaks of Ebola virus disease in Africa [9] and the COVID-19 pandemic have likewise demonstrated how localised spillover events can rapidly escalate into international public health emergencies.
Together, these examples illustrate how environmental change, ecological disruption, and global connectivity are reshaping infectious disease risks across borders. Climate affects not only pathogen survival and vector biology, but also biodiversity, wildlife behaviour, ecosystem stability, and human exposure patterns. Emerging infectious diseases must therefore be understood not solely as biomedical phenomena, but as manifestations of increasingly unstable socioecological systems. At the same time, international travel and trade enable emerging infections to spread rapidly beyond their origins and become regional concerns.
COVID-19 and the limits of reactive preparedness
The COVID-19 pandemic further reinforced the consequences of failing to address ecological drivers of disease emergence. Although the origins of SARS-CoV-2 remain under investigation, the pandemic demonstrated how ecological disruption, wildlife interfaces, and global mobility can rapidly transform localised spillover events into global public health emergencies.
Importantly, COVID-19 exposed limitations in existing preparedness systems. Public health surveillance systems remain largely reactive, focusing on outbreaks after human cases occur. Yet many zoonotic diseases are preceded by measurable environmental and ecological changes, highlighting the need to strengthen climate-informed surveillance systems capable of identifying elevated spillover risk before outbreaks emerge.
Toward climate-informed one health surveillance
The One Health framework provides an important foundation for addressing these challenges. By integrating human, animal, and environmental health surveillance, One Health can improve understanding of disease emergence and support earlier intervention. However, despite widespread policy support, operational implementation remains fragmented across many countries and institutions.
The recent hantavirus event highlights the urgent need to strengthen climate-informed and ecologically informed surveillance systems. Future pandemic preparedness must move beyond reactive outbreak response toward anticipatory frameworks capable of identifying spillover risk before sustained human transmission occurs. Recent advances in remote sensing, artificial intelligence, environmental monitoring, climate forecasting, and predictive analytics provide new opportunities to operationalise this approach. Environmental indicators, including rainfall anomalies, vegetation change, temperature variability, and land-use patterns, may help identify ecological conditions associated with increased disease risk before widespread transmission occurs [10].
An important future direction will be the development of integrated climate-informed early warning systems capable of linking environmental monitoring, ecological surveillance, wildlife reservoir dynamics, and human disease data in near real time. Such systems may help identify ecological conditions associated with elevated spillover risk, support spatial risk prediction, and enable earlier public health intervention before widespread transmission occurs. A conceptual framework for climate-informed infectious disease early warning systems is outlined in Fig. 1.
Fig. 1.
Conceptual framework for climate-informed early warning systems for zoonotic diseases
Summary and perspective
The recent hantavirus event highlights a broader reality in global health: zoonotic spillover is increasingly shaped by climate change, ecological disruption, and global connectivity. The event illustrates how environmental instability and human activity can converge to create new opportunities for disease emergence at the human–animal–environment interface.
More broadly, climate change is no longer simply a contextual background factor for infectious diseases. Rather, it is increasingly reshaping the ecological systems governing reservoir host dynamics, vector ecology, pathogen maintenance, and human exposure patterns. As biodiversity loss, land-use change, and environmental disruption continue to intensify globally, the frequency and complexity of zoonotic spillover events are likely to increase.
These challenges expose important limitations in predominantly reactive outbreak-response systems. Future preparedness will require more anticipatory and integrated approaches capable of linking climate science, environmental monitoring, wildlife surveillance, and public health systems within climate-informed One Health frameworks. Advances in remote sensing, predictive modelling, and environmental intelligence may provide important opportunities to strengthen early warning capacity and improve preparedness for climate-sensitive emerging infectious diseases.
Ultimately, the recent hantavirus event should not be interpreted as an isolated outbreak, but as part of a broader planetary health challenge emerging from increasingly unstable interactions among climate, ecosystems, wildlife, and human societies. Strengthening climate-informed One Health approaches may therefore become one of the most important priorities for reducing future pandemic risk in a rapidly changing environmental future.
Integrating climate, environmental, wildlife, vector, and human disease surveillance data within a One Health framework may improve early detection of zoonotic spillover risk. Such systems can support risk prediction, hotspot detection, early warning, and public health preparedness for climate-sensitive emerging infectious diseases.
Acknowledgements
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Author contributions
WH conceived and drafted the manuscript. WH and TG contributed to the visualisation, review, and revision of the manuscript. All authors read and approved the final manuscript.
Funding
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Data availability
No datasets were generated or analysed during the current study.
Declarations
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Competing interests
The authors declare no competing interests.
Footnotes
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Data Availability Statement
No datasets were generated or analysed during the current study.