Though the outbreak of the Covid-19 pandemic largely took citizens and governments worldwide by surprise, many scientists had been predicting such an event for a long time. Studies linking the health of humans and forest go back more than 40 years, and evidence has increasingly pointed the finger of blame at human-caused damage to forests. Source: Timberbiz
In 2001, a study by the University of Edinburgh’s Centre for Tropical Veterinary Medicine indicated that 75% of all infectious diseases emerging in the last 50 years came from wildlife. These are known as zoonoses, and include HIV, H5N1 bird flu, hantavirus, and most recently, Covid-19.
Subsequent research has linked new infectious diseases to deforestation. Though focusing on different diseases and different regions of the world, these studies have concluded that as forests are destroyed, animals that live in them and can carry diseases to humans, such as rats and bats, are forced into ever smaller areas. This brings them closer to humans, and therefore increases the likelihood of diseases ‘spilling over’, in other words, gaining the ability to jump from one species to another.
One well-known example is the Ebola virus epidemic of 2014–16, which is estimated to have killed over 13,000 people since its discovery in Africa in 1976. The disease was found to have been spread to humans from fruit bats.
Research published in Nature in 2017 found a significant link between outbreaks of Ebola along the edge of rainforests and forest losses within the previous two years. Preventing the loss of forests could reduce the likelihood of future outbreaks, it concluded.
The devastation caused to lives and livelihoods by Covid-19 has put an increasing spotlight on the issue.
Earlier this year, French researchers Serge Morand and Claire Lajaunie made the first attempt to investigate on a global scale whether the loss and gain of forest cover can promote outbreaks of zoonotic diseases. It examined global trends between changes in forest cover in recent decades and epidemics of infectious diseases in humans.
Their research documented that increases in outbreaks of zoonotic and vector-borne diseases from 1990 to 2016 are linked with deforestation, mostly in tropical countries.
However, there are still plenty of unanswered questions. Julia Fa, Professor of Biodiversity and Human Development at Manchester Metropolitan University who co-authored the study on Ebola and deforestation, said that though there was a strong link between deforestation and Ebola, they did not know what occurred in the two years between the two events.
“That’s the million-dollar question! The simplest way of looking at it is that there’s a balance between viruses, pathogens, and animals and if you suddenly disrupt that balance viruses grow in numbers and become much more active in certain periods, and if you have people in between there’s going to be a spread of viruses into animals, and then from animals to people,” she said.
The increased activity of viruses when disturbed has been dubbed ‘viral chatter’ by US researcher Nathan Wolfe.
Links have also been found between reforestation and disease outbreak, since planting trees can also result in disturbing balances in a forest and bring animals and humans closer together.
Morand’s research found this mostly to be the case in temperate countries, and was mainly caused by the planting of monoculture plantations or when land that had previously been savannah or grassland was converted to forests.
To effectively protect forests and prevent disease spillover, experts agree that indigenous people need to be actively involved. Indigenous communities live in a way that aims to preserve the balance of their ecosystems as well as their biodiversity.
