SUMMARY:

We are the first group to predict spillovers of an emerging bat-borne virus. Our work shows how viruses pass from bats to people and provides a method to predict and prevent spillover. Contrary to previous studies that have correlated viral spillover with deforestation and the distribution of reservoir hosts, our work provides spatial and temporal data to identify the mechanistic drivers of spillover. Moreover, our work reveals a solution to preventing spillover: protect and restore the forests that provide food for bats in winter. We integrated social science to empirically identify the narratives that would motivate people to adopt this preventative solution.

OUTCOMES:

We show that spillover is driven by interactions between winter habitat loss and climate-driven food shortages. We were able to predict spillovers of Hendra virus, based on the environmental conditions experienced by bats, and the location of bats. 

We brought together more than 25 datasets to describe the dynamics of Hendra virus that included information on bat behavior, distributions, reproduction and food availability, along with records of climate, habitat loss and environmental conditions. We used Bayesian network models to identify the mechanisms and correctly predicted the presence or absence of clusters of spillover in every year over the past 25 years. We showed that the loss of winter habitat was the key trigger to the emergence of Hendra virus and showed that when remnant winter forest produced abundant nectar, the bats left agricultural areas to feed in these patches of native forest, and spillover stopped. Our work suggests that regeneration of winter habitat should be an effective solution to spillover. This work was published in Nature (Eby et al. 2022, doi.org/10.1038/s41586-022-05506-2).

We used data on ecological history of bat populations, to show that only bats that have been displaced to novel habitats excreted more virus in winter. However, after a food shortage, all bat populations shed more virus, especially the bats in novel overwintering habitats. These results were recently published in Ecology Letters (Becker et al. 2022, doi.org/10.1111/ele.14007) and show an important mechanism linking land-use change, habitat loss, and spillover. 

We discovered that the amount of virus excreted by bats, rather than the proportion of bats excreting virus, is more important for explaining spillover patterns. Low-prevalence of Hendra virus outside of high risk periods may be non-infectious RNA shedding and may not contribute to spillover risk. Moreover, when bats shed more virus, such as after food shortages, they synchronously excreted a community of paramyxoviruses in a pulse (Peel et al. 2019). Given the novel way bats excrete viruses, we developed new methods and frameworks for modeling the dynamics in bats (Glennon et al. 2019, Giles et al. 2021, Hoegh et al. 2021, Lunn et al. 2021a, 2021b, 2021c). 

We worked with local and national restoration groups to incorporate bat winter habitat restoration into their activities. With collaborators, we developed and launched a free, online, archive of habitat restoration sites to increase the extent and viability of key winter habitat on the ALA BioCollect platform. This novel initiative provides a tool for restoration practitioners and has received wide support within Australia?s ecological restoration community.

We studied the narratives that change people's attitudes to bats, bat management, and spillover mitigation. We found that stories with characters and photographic images are more effective than information-only messages at mobilizing support for different forms of bat management, including habitat restoration (Guenther and Shanahan 2020). We also found that the more complex One-Health risk message leads not only to greater policy support for preventative measures, but also to greater support for a wider array of policy interventions. We are now working to incorporate these narratives in advocating for ecological countermeasures to spillover. Our findings also include data on an individual's primary source of information on Hendra virus, attitudes towards bats and Hendra virus vaccination to inform risk communication efforts. 

Our work is now influencing pandemic response and funding policies. Pronounced focus on medical countermeasures (e.g., detection, vaccination, and therapeutics) risks exclusion of spillover countermeasures, due to the erroneous perception of spillover as unsolvable, complex, and unclear. Our work on Hendra virus counters these concerns by showing spillover can be predicted and prevented by addressing underlying drivers of spillover cascades. Our empirical social science identified the narratives that will be most effective at encouraging adoption of preventative (rather than reactive) policies.  

This project supported 6 PhD students (5 female), 1 MS student (female), 5 postdocs (2 female), and 9 undergraduates (7 female). We published 73 papers in peer-reviewed journals, and multiple papers are in-review or preparation. We had over 68 media engagements and then >360 headlines that featured our paper in Nature, including in the New York Times, NPR, Nature News, and Le Monde. We engaged with community and policy-makers, and gave over 75 presentations to scientific audiences, policy-makers, and the general public.

Last Modified: 01/28/2023
Modified by: Raina K Plowright