Land use changes increase risk of diseases like COVID-19

Land use changes worldwide are increasing the risk of zoonotic disease outbreaks like COVID-19, according to a new study from University College London. 

By altering landscapes, humans are disrupting the balance of wild animal communities, and the researchers found that land use changes often tip this balance in favor of animals that carry infectious pathogens.

The analysis also showed that animals with zoonotic diseases were more common in landscapes that were used the most intensively by people.

The investigation was focused on 184 studies, including evidence from 6,801 ecological communities across six continents. The dataset involved nearly 7,000 species, and 376 of these species are known to carry human-shared pathogens.

Study lead author Rory Gibb is a PhD candidate at the UCL Centre for Biodiversity & Environment Research. 

“The way humans change landscapes across the world, from natural forest to farmland for example, has consistent impacts on many wild animal species, causing some to decline while some others persist or increase,” said Gibb.

“Our findings show that the animals that remain in more human-dominated environments are those that are more likely to carry infectious diseases that can make people sick.”

In the environments that had been disturbed by humans, animals that host zoonotic pathogens made up a higher proportion of the species present compared to ecological communities in wild habitats that were not influenced by humans. This was found to be the case for animals that carry more infectious pathogens of any kind, regardless of whether they threaten humans.

By comparison, most other wild animal species are found in lower numbers in human-altered environments. According to the researchers, this unequal balance suggests that similar factors may be influencing both whether a species can tolerate humans and how likely it is to carry potentially zoonotic diseases.

“Other studies have found that outbreaks of emerging zoonotic infectious diseases appear to be increasingly common – our findings may help to explain that pattern, by clarifying the underlying ecological change processes that are interacting to drive infection risks,” said study co-lead author author Dr. David Redding.

“Global land use change is primarily characterised by the conversion of natural landscapes for agriculture, particularly for food production,” said study senior author Professor Kate Jones. “Our findings underscore the need to manage agricultural landscapes to protect the health of local people while also ensuring their food security.”

The researchers said that while there are numerous other factors influencing emergent disease risks, the findings point to strategies that could help mitigate the risk of further infectious disease outbreaks comparable to COVID-19.

“As agricultural and urban lands are predicted to continue expanding in the coming decades, we should be strengthening disease surveillance and healthcare provision in those areas that are undergoing a lot of land disturbance, as they are increasingly likely to have animals that could be hosting harmful pathogens,” said Professor Jones.

The study is published in the journal Nature.

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By Chrissy Sexton, Earth.com Staff Writer