Impacting Public Health: People, Animals and the Environment

Rebecca Kaplan, Ph.D.

This blog post is part of a weekly series focusing on different aspects of public health leading up to Public Health Thank You Day on Monday, November 21, 2016. Join the conversation on social media with the hashtag #PHTYD and visit for more information.

While One Health or One Medicine is a relatively new idea, humans have long recognized the connection between animals, humans, the environment and health. Chinese scholars in the last three centuries BCE interpreted the earth and human body as interdependent and that if the land was unhealthy so was the body. Writings from the Hippocratic Corpus (composed between the sixth and fourth century BCE) include sections that instruct practitioners to think about environment and locations when diagnosing disease, comparing human and cattle anatomy. In many cultures, human understanding of the body and disease was shaped by comparative anatomy and pathology studies since human dissection was taboo. While veterinary and human medicine developed as separate fields in what is now Europe, the Middle East, India, and China, practitioners in both disciplines utilized similar theories of disease causation and medical treatments. There was a commonality about how weather, environment and other factors impacted both the animal and human body and how to restore health to those inflicted.

Though medical practitioners and healers recognized the similarities in health between animals and humans and the impact of the environment on both, changing theories about disease causation in the last several centuries revealed the intimate relationship between them. For example, in the early 19th century, there were various theories about why people developed tuberculosis. A century later, new laboratory technology and medical theory indicated that people contracted the disease from infected people, often in overcrowded cities or from infected cows via unpasteurized milk. People’s living conditions and close proximity to livestock increased their exposure to the tuberculosis bacterium and risk of the disease. Many medical professionals, health officials and advocates used this information to lobby for policies that tackled the sources of infection such as dismantling tenements, closing poorly ventilated workshops, mandating pasteurization and culling diseased cattle. Understanding the role of the environment and livestock in the spread of tuberculosis allowed people to create programs aimed at preventing new cases of the disease.

From ancient healers cauterizing dog bites to prevent “madness” (rabies) to modern researchers studying the role of climate change in the recent Siberian anthrax outbreak, understanding the interrelationship of human health, animal health and the environment impacts how people approach preventing and treating disease. One Health is designed to explicitly recognize this connection and encourage interdisciplinary medical and environmental research to solve our current and future health crises.

Rebecca Kaplan, Ph.D., is the Mellon/ACLS Public Fellow at the Pulitzer Center.

Photo Credit: Unknown. 1905. “Trichina inspection laboratory, Chicago, Illinois; man with beard may be Thornberry.” Special Collections, USDA National Agricultural Library.



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Without continued support for health research, many of the most promising young scientists, their ideas and a myriad of potentially life-changing scientific breakthroughs will vanish into oblivion.
Paul Marinec, PhD; University of California San Francisco