A new study has found that human proximity to deforested areas poses an increased risk of the outbreak of zoonotic viruses.
This adds to a growing body of evidence that human encroachment on the natural environment is resulting in zoonotic disease outbreaks.
Deforested areas and even monocultures such as commercial forests planted by humans are linked to the outbreak of diseases, the researchers found.
The researchers explained that a forest’s healthy diverse ecosystem with a range of species, blocks and filters viruses. However, in the case of monocultures where single species of plants are cultivated, like a palm oil plantation, specialist species die off and are replaced by generalists such as rats which then spread pathogens on to humans.
“I was surprised by how clear the pattern was,” said one of the study authors, Serge Morand, of the French National Centre for Scientific Research. “We must give more consideration to the role of the forest in human health, animal health and environmental health. The message from this study is ‘don’t forget the forest’.”
Using a number of databases from sources such as the World Health Organization, the researchers analysed the relationship between changes in forest cover, plantations, population and disease around the globe.
Over 1990 to 2016, the study period covered 3884 outbreaks of 116 zoonotic diseases that crossed over into humans and 1996 outbreaks of 69 vector-borne infectious diseases, largely carried by mosquitoes, ticks or flies.
“Everyone in the field of planetary health is worried about what is happening to biodiversity, climate and public health in Brazil,” Morand emphasised. “The stress there is growing. The Amazon is near a tipping point due to climate change, which is not good at all for the world ecosystem. If we reach the tipping point, the outcomes will be very bad in terms of drought, fires and for sure in terms of disease.”
The rainforests of the Congo basin and south-east Asia, and monoculture afforestation projects around the world were also cause for concern. “Our results clearly suggest that it is not only forest clearance that is responsible for outbreaks of infectious diseases, but also reforestation or afforestation, particularly in countries outside the tropical zone,” the paper noted.
Morand’s next study involves examining forest cover with satellite imagery and exploring links with that to disease.
Source: The Guardian
