Author: Antonia Truta, Class of 2028
The World Health Organization’s definition of zoonosis is any disease or infection naturally transmissible from animals to humans, or vice versa. Animals are important to understanding disease transmission, with over 60% of emerging infectious diseases having zoonotic origins.
Yet, to fully understand the context of zoonotic disease outbreaks, we must look at our interactions with nature in a larger sense. ‘Climate change’ refers to how industrial processes like the burning of fossil fuels for energy increase the rate of climate change, disturbing the slow, natural process of Earth’s atmosphere. Presently, climate change causes unnaturally high global temperatures, which has led to new and persistent trends in zoonotic disease transmission. Monitoring environmental shifts is vital to predicting outbreaks.
Abdallah Borham and colleagues at the American University in Cairo published in the International Journal of Environmental Research and Public Health presenting an encompassing “One Health” approach by exploring the interconnectedness between human health, animals, and our environment. The bat-human interaction that ultimately led to the lethal and global COVID-19 pandemic has brought this connection to the public consciousness in recent times.
The authors elaborate that vector-borne, mosquito-borne, tick-borne, waterborne, foodborne, airborne, and rodentborne diseases are all climate-driven and often zoonotic. Extreme weather can expand the range of location and the lifespan of disease-causing bacteria and pathogens such as malaria, cholera, plague, and dengue, which have all been shown to have strong correlations to climate anomalies such as extremely high temperatures. For example, malaria and dengue are transmitted by infected mosquitoes, and plague is transmitted often by infected rodents or the fleas that feed on them.
The authors summarize climate-driven spread of a zoonotic disease in four stages: climate-induced migration of animals from their natural habitats, therefore increasing contact with humans; pathogen spillover from wildlife to humans due to environmental disruption; human-to-human transmission of the new infection; exponential disease spread, leading to outbreaks or pandemics.
In essence, emerging infectious diseases are intensified by climate change, deforestation, agricultural land-use, urbanization, and more human-animal interactions. Previous studies have shown that air pollution leads to inflammation and infectious vulnerability with our immune systems, and that toxic yet common industrial chemicals, like pesticides, can lead to immunosuppression and cancers. Our health is irrevocably tied to our environment, and given the unstable and rapidly changing global environment, these studies present a pressing need for closer monitoring of both emerging and mutating zoonotic pathogens.
Works Cited
[1] Borham, A., Abdel Motaal, K., ElSersawy, N., Ahmed, Y. F., Mahmoud, S., Musaibah, A. S., & Abdelnaser, A. (2025). Climate Change and Zoonotic Disease Outbreaks: Emerging Evidence from Epidemiology and Toxicology. International Journal of Environmental Research and Public Health, 22(6), 883. https://doi.org/10.3390/ijerph22060883
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