Bard College Biology Professor Felicia Keesing Coauthors Overview of New Global Study Showing that Human-Caused Changes to Ecosystems Favor Species Most Likely to Cause Human Illness
Large-Scale Study, Published in Nature, Supports Findings of Keesing and Colleague Richard S. Ostfeld’s Two Decades of Research on Lyme Disease Ecology and Other Linkages Between Ecology, Conservation, and Human HealthThe COVID-19 pandemic triggered by a coronavirus of animal origin has awakened the world to the threat that zoonotic diseases pose to humans. While examples of land-use changes increasing the risk of zoonotic disease have been accumulating for decades, questions have remained about the scale of the pattern and its specific underlying mechanisms. In a new large-scale study, “Zoonotic host diversity increases in human-dominated ecosystems,” Rory Gibb, Kate Jones, and their coauthors find global evidence that human land use changes natural habitats in ways that favor animals more likely to cause human illness. The study, published today in the journal Nature, strongly supports the findings of Bard College Biology Professor Felicia Keesing and her husband and research partner Richard S. Ostfeld’s two decades of extensive research on Lyme disease ecology and other linkages between ecology, conservation, and human health.
“The transformation of forests, grasslands, and deserts into cities, suburbs, and agricultural land has caused many species to decline or disappear and others to thrive,” write Ostfeld, a disease ecologist at the Cary Institute for Ecosystem Studies, and Keesing in a general overview of the primary study published concurrently by Nature. “The winners are often generalists that are small, abundant and have ‘fast’, short lives, such as rats and starlings. Gibb et al. show that, worldwide, these winners are much more likely to harbor disease-causing agents (pathogens) than are the losers. As a result, when we convert natural habitats to our own uses, we inadvertently increase the probability of transmission of what are known as zoonotic infectious diseases, which are caused by pathogens that can jump from animals to humans.”
Ostfeld, and Keesing write that the patterns that Gibb and his coauthors detected from their analyses—which explored 6,801 ecological communities and 376 host species worldwide—were striking and provide strong evidence to lingering questions about the global scale and mechanisms of zoonotic disease transmission. “Is it simply a coincidence that the species that thrive in human-dominated landscapes are often those that pose zoonotic threats, whereas species that decline or disappear tend to be harmless? Is the ability of animals to be resilient to human disturbances linked to their ability to host zoonotic pathogens?” write Ostfeld and Keesing. “Gibb et al. found that the animals that increase in number as a result of human land use are not only more likely to be pathogen hosts, but also more likely to harbor a greater number of pathogen species, including a greater number of pathogens that can infect humans.”
With awareness of and concern about zoonotic diseases surging in the wake of the COVID-19 pandemic, Ostfeld and Keesing write that—by showing that the greatest zoonotic threats arise where natural areas have been converted to croplands, pastures, and urban areas—Gibb et al correct the widespread misperception that wild nature is the greatest source of zoonotic disease. This study and others strongly suggest that restoring degraded habitat and protecting undisturbed natural areas would benefit both public health and the environment. “Going forward, surveillance for known and potential zoonotic pathogens will probably be most fruitful if it is focused on human-dominated landscapes,” they write.
To read the full study in Nature, click here. To read Ostfeld and Keesing’s overview, click here.
Felicia Keesing, David and Rosalie Rose Distinguished Professor of Science, Mathematics, and Computing, has been on the Bard faculty since 2000. She has a B.S. from Stanford University and a Ph.D. from the University of California, Berkeley. Since 1995, she has studied how African savannas function when the large, charismatic animals like elephants, buffaloes, zebras, and giraffes disappear. She also studies how interactions among species influence the probability that humans will be exposed to infectious diseases. Keesing also studies Lyme disease, another tick-borne disease. She is particularly interested in how species diversity affects disease transmission. More recently, she has focused on science literacy for college students, and she led the re-design of Bard College’s Citizen Science program. Keesing has received research grants from the National Science Foundation, National Geographic Society, National Institutes of Health, Environmental Protection Agency, and Howard Hughes Medical Institute, among others. She has been awarded the United States Presidential Early Career Award for Scientists and Engineers (2000). She is the coeditor of Infectious Disease Ecology: Effects of Ecosystems on Disease and of Disease on Ecosystems (2008) and has contributed to such publications as Nature, Science, Proceedings of the National Academy of Sciences, Ecology Letters, Emerging Infectious Diseases, Proceedings of the Royal Society, Ecology, BioScience, Conservation Biology, and Trends in Ecology & Evolution, among others.
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