Climate change is likely to push rodent-borne arenaviruses into regions of South America that have never faced these diseases, putting new human communities at risk, a University of California, Davis study found.
For research published in journals, npj virusScientists incorporated climate projections, rodent population trends, and human infection risk into their models to provide early risk predictions for arenaviruses and other diseases over the next 20 to 40 years.
As climate change accelerates, our research shows that the risk of dangerous new world arenavirus outbreaks could extend to millions more across South America as rodent populations change. ”
Pranav S. Kulkarni, first author, postdoctoral fellow in the UC Davis Weill School of Veterinary Medicine and the Department of Population Health and Reproduction
South American New World Arenavirus
Arenaviruses can cause severe hemorrhagic fevers, with high hospitalization rates and a case fatality rate of approximately 5% to 30%. South American New World arenaviruses include Guanaritovirus from Venezuela and Colombia, Machupovirus from Bolivia and Paraguay, and Junín virus from Argentina. Despite causing multiple epidemics in humans, it is relatively less studied compared to Old World arenaviruses such as Lassa fever in Africa.
With funding from the Wellcome Trust, researchers built an interactive open-source platform called AtlasArena to understand how climate change is reshaping zoonotic spillover risks for arenaviruses and other hard-to-trace viruses. They integrated climate projections, habitat suitability for six rat and mouse species associated with the virus, human population density, and infection risk into a machine learning model. This approach allowed the team to identify complex relationships between climate, land use, rodent ecology, and human exposure that traditional models often miss.
Where arenaviruses may appear next
Our study connects the dots between changing climate conditions and land use, changes in rodent populations and human infection risk, allowing us to see where the next generation of zoonotic arenavirus outbreaks will occur. ”
Pranav Pandit, senior author, assistant professor of veterinary epidemiology, University of California, Davis Weill School of Veterinary Medicine
For example, the model predicts:
- The Guanarito virus originated in central Venezuela and is expected to spread to parts of Colombia, the Suriname border, and northern Brazil.
- The Machupo virus is expected to migrate from the plains and plains of Bolivia to the foothills of the Andes and mountainous regions.
- The Junín virus is expected to move from grassland areas to other parts of Argentina, reducing the risk in some areas and increasing the risk in others.
- In both cases, people with little or no previous infection may be encountering these viruses for the first time, increasing their vulnerability to infection and severe disease.
Runoff risks are primarily caused by changes in temperature, precipitation, and land use, such as the expansion of agricultural and urban areas within rodent habitats.
Coordinated cross-border public health needs
The authors say the results support the urgent need for climate-adapted public health policy coordination and cross-border cooperation among at-risk countries.
“The first thing a study like this tells us is where we would expect the risk to increase,” Kulkarni said. “Then we can look more closely at why it’s happening, identify ways to reduce the risk, and begin long-term planning and ways to reduce the spread of the disease.”
The authors note that research using the AtlasArena platform is ongoing and freely available, and its insights can be applied to research into other climate-sensitive diseases that are poorly monitored and spread by animals.
Additional co-authors of the study include Nuri Flores-Perez of the University of California, Davis (now the San Diego Zoo), Andy Jiang, Brian Byrd, Kristin Johnson, and Marcela Woohart of the University of California, Davis Weill School of Veterinary Medicine.
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University of California, Davis
Reference magazines:
Kulkarni, P.S. Others. (2026). Climate-induced changes in the zoonotic risk of arenavirus hemorrhagic fever in South America. npj virus. DOI: 10.1038/s44298-026-00189-2. https://www.nature.com/articles/s44298-026-00189-2
