The emergence of COVID-19 and the negative impacts that wildlife-to-human disease transmission have had on human societies has been the central global science story of recent years. A strong second contender is the looming existential risks presented by our steadily warming planet.
Now, a National Science Foundation (NSF) Faculty Early Career Development (CAREER) award will give Assistant Professor Luis Escobar of the College of Natural Resources and Environment the chance to consider both research dimensions while exploring disease transmission across two continents.
“We are using hantavirus as our biological model,” said Escobar, who teaches in the Department of Fish and Wildlife Conservation. “The goal is to understand how climate change is going to influence the spillover transmission of viruses, both between wildlife species and to human populations.”
Hantavirus is an established and well-documented virus that causes infection when humans encounter rodent droppings. Two divergent strains of the virus impact human health. In Europe, Asia, and Africa, a more common strain causes hemorrhagic fever and kidney dysfunction for some 200,000 individuals annually. A rarer – and significantly more severe – strain of the virus impacts pulmonary and cardiovascular functions in people living across North and South America.
“This is a virus that we can track very well, to the point where if you have one kind of virus, scientists can tell you the most likely species of rodent it came from and how aggressive or virulent the virus will be to an infected individual,” said Escobar, who is an affiliated faculty member of the Global Change Center and the Fralin Life Sciences Institute’s Center for Emerging, Zoonotic, and Arthropod-borne Pathogens. “That base of knowledge allows us to test what-if scenarios, such as what if a climate becomes warmer? How does that impact disease transmission?”
Escobar's aim is to assess the “biogeography” for the virus, which would merge geographic information about rodent populations, data on virus occurrence, and spillover transmission between wildlife and humans with broader climate and environment factors. That convergence of information could help researchers understand why the Western Hemisphere strains of hantavirus spike to impact human health in some places, while remaining dormant elsewhere.
Sourcing data from across the hemisphere
To gather information on rodent populations across the United States, Escobar will use data collected by the NSF’s National Ecological Observatory Network (NEON), which gathers data from 81 field-sites across the country to provide researchers with open-source data.
“NEON has been sampling rodents since 2014 and testing them for hantavirus,” said Escobar. “So far, they have tested some 12,000 samples of rodents. With this project, we’re going to tap into that enormous resource to answer some of the fundamental questions about host-virus dynamics.”
In addition to understanding hantavirus spread in the U.S., Escobar will do parallel research in Chile, where there are consistent annual cases of a hantavirus strain in humans spread by the droppings of pigmy rats and long-haired grass mice.
“Chile covers the same latitudinal – or north-to-south – line as the U.S., and we want to use it as a mirror location to do sampling on animals,” Escobar said. “If the signals we detect in North America are consistent in South America, that will allow us to develop new theories about how this virus evolves.”
Escobar, who will develop and teach a first-ever course in disease biogeography as part of this award, is the faculty advisor for the Wildlife Disease Association Student Chapter at Virginia Tech, a student club that aims to gain and disseminate information about wildlife disease to protect the health of animals and humans.
“The more than 25 students officially involved in the club have a range of interests,” Escobar said. “Some are interested in animal health, while others are interested in biodiversity conservation. And we have students who are interested in the human health dimensions of disease spread.”
Escobar will dedicate some of the grant to fund student exchange opportunities with universities in Chile. He will also develop his disease biogeography course in both English and Spanish so the materials are available for researchers in Latin America.
Measuring the potential of pandemic
While hantavirus remains rare in humans, there is concern among epidemiologists that it could one day evolve to become a pandemic risk.
“Right now, there are very few cases where hantavirus has spread from human-to-human contact,” Escobar said. “So far, that is an advantage for us. But viruses evolve and adapt all the time. If we can better understand both how the virus evolves and what environmental factors impact that spread, we’ll be better prepared to deal with future challenges.”
Professor Joel Snodgrass, head of the Department of Fish and Wildlife Conservation, echoes the critical importance of Escobar’s research into hantavirus.
“Dr. Escobar’s study is truly deserving of support as he is addressing significant human health questions with a study design that allows extrapolation at a global scale,” said Snodgrass. “On the other hand, Dr. Escobar is bringing his work home through his teaching, engagement of undergraduates in research, and support of the Wildlife Disease Club. The link between impactful research and teaching is exactly what NSF CAREER awards are designed to promote.”
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