UNIVERSITY PARK, Pa. — Preserving and restoring natural habitats in specific locations could prevent pathogens originating from wildlife from spilling over into domesticated animals and humans, according to new research led by an international team of researchers, including Penn State.
The research, carried out in Australia, found that when bats lose winter habitats and lack food in their natural habitats, their populations split and they excrete more virus. Bats disturbed by a lack of food move near humans in agricultural and urban areas. The team studied Hendra virus, a deadly virus that flows from fruit bats to horses and then infects people.
“One of the biggest challenges we face are threats from bat-borne viruses that spill over into humans and have the potential to cause pandemics. Ebola, MERS, SARS, SARS-CoV-2, Nipah and Hendra are all good examples of this,” said Peter Hudson, Willaman Professor of Biology, Penn State. “The response to the pandemic has been to find ways to speed up the development of vaccines, but as infections invariably spread much faster than the introduction of the vaccine, this reactive response will never stop a pandemic. Instead, the solution is to prevent viral spillover from bats to humans.”
The team’s research, published on November 16 in Nature, combined multiple data sets over 25 years on bat behavior, distributions, reproduction and food availability, along with records of climate, habitat loss and environmental conditions. In order to link these data and seek insight into the causes the researchers used Bayesian network models.
They documented more than 60 Hendra virus spillover events during the 25-year period. Although previous research has shown a correlation between habitat loss and the influx of pathogens, this study reveals for the first time a mechanism for how and why viruses transfer from bats to humans. Furthermore, their work provides a method to predict and prevent them.
“Bats usually live in large aggregations with thousands of bats in camps and will move great distances for their sugary nectar. We found that following a severe El Nino (high temperature in the Pacific) climatic event, the cold and rainy weather inhibited flower production,” said Hudson. “With a lack of food, the young of the bats die and the hungry adults move away to small aggregations where they start shedding virus – often in habitats they have never been seen in before .”
“In agricultural areas, the bats shed the virus when they re-grow half-eaten fruit or transfer the virus in urine and faeces to the pasture where horses graze. The horses then become infected with the Hendra virus and exhibit severe neurological symptoms,” said Hudson. “And when the concerned owners come to examine the sick horse they get a large dose of the fatal virus.”
Much to their surprise, the researchers discovered that when the stands of eucalyptus trees that remained in winter bloomed, a large number of bats flocked to these areas. During those flowering events, pathogen spillover stopped immediately. Hudson said, “it was like the perfect experiment – any unexpected flowering stopped immediately.”
“We think this shows how important it is to restore native habitats, and we are developing ideas for restoring vital food trees for bats, effectively planting trees for human health,” Hudson said.
Raina Plowright, professor in the Department of Public Health and Ecosystem at the College of Veterinary Medicine, added, “Right now, the world is focused on how we can prevent the next pandemic. Unfortunately, preserving or restoring nature is rarely part of the discussion. We hope this paper will bring prevention and nature-based solutions to the forefront of the conversation.”
Other authors on the paper include Peggy Eby, University of New South Wales; Alison Peel, Griffith University; Andrew Hoegh, Montana State University; Wyatt Madden, Montana State University; and John Giles, Johns Hopkins Bloomberg School of Public Health.
The National Science Foundation, the US Defense Advanced Research Projects Agency, and the US National Food and Agriculture Organization, and the Australian Research Council, supported this research.