Bat ecology helps us understand how zoonotic spillover occurs – and how to prevent it: study

Ecological tools to prevent zoonotic spillover events, using bats as a model. Image from Plowright et al 2024.

Zoonotic spillover events have been the source of many of humanities most notorious pandemics. A spillover event occurs when a zoonotic disease jumps from its normal animal host into a human, causing an infection. But what if instead of looking at spillover events as the starting point, we rather looked at them as the end point of a complex cascade of risk factors aligning – the coming together of multiple processes so that the pathogen and the people are brought together for a 'right place, right time' moment?

That's the approach of a recently published Nature study by a collaboration of researchers across 8 different institutions. They argue that preventing the next pandemic means filling in the gaps about why these spillover events occur in the first place. This approach is a vital complement to the pandemic preparedness and response activities that most people are familiar with, like vaccinations, medical therapy and public health measures.

What's so special about bats?

Bats are the perfect model for thinking about spillover events and why they occur. We know that bats harbour a range of viruses that can infect humans, without becoming ill themselves – and when they're stressed by not having enough suitable food or habitat, especially when they're breeding or migrating, they shed these viruses. When resources are scarce, bats are forced closer to humans to look for food and shelter, and human behaviours (like mining guano, farming date palm sap, or hunting bats for food) can also increase interactions with bats. It's in situations like these that zoonotic spillover occurs.

The researchers take these real-world examples and propose a set of ecological countermeasures that can be applied across a broad range of potential pandemic pathogens, even though these pathogens may live in vastly different animal reservoirs and environments. The core message is this: if we do the work to understand disease ecology and preserve high-quality wildlife habitat, and take care with the way we use land so that we minimise the disruption of natural ecological cycles, we can reduce interactions between stressed wildlife and people and interrupt the pathway from pathogen to people.

'In our view, the most effective strategy to reduce the probability of another pandemic is to preserve intact ecosystems and bolster their resilience through restoration and the creation of buffer zones.'

Plowright et al 2024

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