Shifting natural landscapes to land that humans use for farming increases the arrival of species capable of transmitting disease to humans.

Andalusian countryside

The global transformation of the natural environment for agricultural use, ranching or urban has upset the balance of wild animal communities. A study led by several British institutions has shown that the species that carry zoonotic diseases, known to infect humans, benefit from these changes in land use.

“It is difficult to know if the risk of these types of ailments is higher now than in the past. However, at this time there are many factors that increase the likelihood that Isolated disease outbreaks become major epidemics. For example, the world is much more connected by road and by air than ever, so it is easy for diseases to spread more rapidly to more densely populated areas, “says Rory Gibb, co-author of the study and scientist at the Center for Biodiversity and Environment Research from University College London.

For the study, the researchers agreed to PREDICTS, a database that collects information on local species from hundreds of studies on ecological communities, throughout landscape disturbance gradients, from natural vegetation to ecosystems agricultural and urban.

The team used 6,801 locations around the world to analyze how populations transform and zoonotic host species communities, on average, as landscapes change from natural vegetation, to agricultural, grassland, and urban ecosystems.

“We found that, under increasing intensities of human land use, ecological communities move to become increasingly dominated by zoonotic host species, particularly in habitats secondary (recovered), managed (agricultural and plantation) and urban ”, emphasizes Gibb.

The work, which is published in the magazine Nature, can help you prevent future contagion of diseases originating from animal hosts. “There is some evidence that the new zoonoses [patógenos nuevos y antes no descubiertos] are emerging at an ever-increasing rate and that this may be due to increasing rates of human-driven impacts on the environment and biodiversity. ” says the co-author.

But, he adds, “this trend is difficult to measure conclusively. Undoubtedly, the use of improved diagnostics and new genomic technologies will help us to advance in the detection of new diseases“.

However, these responses depend on the grouping of some particular species: roebats, passerines, and bats show a particularly clear and strong divergence between host and non-host species, while in carnivores and primates it is not detected, according to the study.

Food safety

The researchers stress that we may have to alter the way we use the land worldwide, to reduce the risk of future contagious effects of infectious diseases.

Global land use change is mainly characterized by the conversion of natural landscapes for agriculture, particularly for food production. “Our findings underscore the need to manage agricultural landscapes to protect the health of local people while ensuring their food security,” says Kate Jones, co-author and researcher at University College London (UCL).

These zoonotic ailments such as Ebola, Lassa fever, and Lyme disease, which are caused by pathogens that spread from animals to people and have a high health cost.

“The pzoonotic allude, for example, is transmitted between primates, mosquitoes, and humanss around the forest margins in Southeast Asia. The Nipah virus first emerged in association with interactions between cattle and bats in agricultural landscapes. Another important and widespread disease is Lyme disease, the incidence of which is often higher in fragments of modified and recovering forests, where the ecological community is particularly effective in transporting and transmitting the bacteria, ”says Gibb.

The researchers emphasize that while there are many other factors that influence disease risks, the results point to strategies that could help mitigate the risk of infectious disease outbreaks comparable to COVID-19.

“As agricultural and urban lands are forecast to continue to expand in the coming decades, we should strengthen disease surveillance and disposition in those areas that are experiencing a lot of land disturbance as it is increasingly likely they have animals that could be harboring harmful pathogensJones adds.

For his part, David Redding, another of the UCL authors, emphasizes that the work “provides a context to reflect on more sustainable changes, so that potential risks are taken into account, not only for biodiversity, but also for human health ”.