Human activities like deforestation and climate change are driving a global increase in emerging infectious disease outbreaks, according to a study published in Nature. Researchers analyzed tens of thousands of outbreak events across 169 countries, revealing that socioecological landscape changes and declining healthcare access strongly shape how these health threats emerge and spread.
Global Assessment of 32 Diseases Across 169 Countries
An international research team has completed one of the largest data-driven assessments examining how environmental and social conditions influence disease outbreaks according to a study published in Nature. The project analyzed 58,318 outbreak events involving 32 distinct diseases across 169 countries. Co-led by University of Florida medical geographer Sadie Ryan alongside scientists from University College London and Yale University, the research set out to test for a general, detectable anthropogenic fingerprint on human infection risks.
Also contributing to the UF team were geography postdoctoral associate Catherine Lippi, Ph.D., and Jason Blackburn, Ph.D., who serves as a professor and chair in the Department of Geography. Both Ryan and Blackburn are principal investigators with UF’s Emerging Pathogens Institute. Using current geolocated outbreak case records along with gridded datasets of major socio-environmental disease drivers, the research evaluated whether human-caused factors left a broad, detectable imprint on where outbreaks of 32 emerging infectious diseases occurred geographically.
To account for differing ecological characteristics across diseases and avoid testing for spurious or irrelevant associations, the co-authors completed a participatory form-based exercise. This drew on specialized expertise spanning a wide range of disciplines and scales of enquiry, from virology, to ecology, to global public health. Utilizing geospatial logistic regression models, the investigators then evaluated outbreak risk drivers through a standardized statistical framework that harmonized both point and polygon data.
Environmental Changes, Deforestation, and Climate Drivers
Infectious disease outbreaks are on the rise worldwide, with human actions such as deforestation and climate change playing a partly responsible role in the trend. The researchers discovered that outbreaks occur most frequently where human populations and livestock live alongside forests and other changing environments. Long-term declines in rainfall also compound these pressures.
Mosquito- and tick-borne illnesses such as Lyme disease and dengue relied particularly heavily on these precise environmental factors combined with extended reductions in rainfall. Still, the analysis revealed that the specific catalysts connected to disease outbreaks vary from one illness to another. When examining pathogens spread directly between humans—such as coronaviruses, mpox, and Ebola—the investigators identified very few environmental variables that reliably forecasted outbreak locations.
Sadie Ryan, University of Florida medical geographer
Ryan emphasized the complexity of these dynamics, noting that spillover disease outbreaks are multicausal, shaped by the socioecological system. This really highlights the need for One Health integrated approaches to surveillance and intervention,
Ryan said. There is no single intervention strategy.
Healthcare Access Gaps and Surveillance Challenges
Environmental pressures tell only part of the story. The data revealed that local access to healthcare heavily influences where disease outbreaks are officially reported. For every additional hour of travel required to reach the closest medical facility, documented outbreak reports declined by 32%, indicating that regions with restricted medical infrastructure and surveillance might experience undetected outbreaks.
Data availability also presents hurdles for researchers tracking high-concern pathogens. Because documented confirmed spillover events remain too sparse to establish a reliable geographic risk profile, researchers lacked adequate or appropriate data for several high-priority illnesses, most notably SARS-related coronaviruses.
Targeted Monitoring and Integrated Intervention Strategies
Addressing the rising tide of emerging infections requires looking beyond broad environmental management. Because disease drivers vary wildly from vector-borne illnesses to direct human-to-human pathogens, public health strategies must adapt. Enhanced medical care, stronger disease surveillance, and localized strategies custom-built for specific regions and conditions will play a crucial role in spotting novel threats and stopping outbreaks from expanding, according to the researchers.
