Providing access to health care services during the pandemic in Eswatini
Providing access to health care services during the pandemic in Eswatini.

Deforestation Makes Pandemics More Likely

By Eric Haxthausen

This is the first of three blogs examining the lessons and implications of the COVID-19 pandemic for sustainable landscapes programs. The second blog examines the issues of the COVID-19 pandemic for sustainable landscape programs, and the third blog considers the role of sustainable landscapes in pandemic response. 

At a time when everyone is focused on the novel coronavirus disease 2019 (COVID-19) some might think that ongoing efforts to support programming in sustainable landscapes have little to offer at the current moment. This series of blogs will seriously challenge that assumption. In the age of COVID-19, sustainable landscapes programs are more important than ever. And investments in forest conservation may actually be some of the smartest, most cost-effective investments we can make to protect public health.

Regardless of its own origins, which remain undetermined, the ongoing COVID-19 pandemic has highlighted the fact that continued deforestation and forest fragmentation makes future pandemics more likely. Scientists have known for a while that pandemics are most likely to arise when a novel pathogen crosses over to humans from other animals. These so-called zoonotic diseases, which include six out of every ten infectious diseases in people, in turn, arise most readily in contexts where humans interact with wildlife. This commonly happens at the forest margin, which often expands where there is deforestation and forest fragmentation.

Indeed, research suggests that land use change is the leading driver of zoonotic disease transmission to humans, followed distantly by agricultural industry change and international travel and commerce. As a recent article in the journal Science noted, “Roadbuilding, mining and logging camps, expansion of urban centers and settlements, migration and war, and livestock and crop monocultures have led to increasing virus spillovers. Hunting, transport, farming, and trade of wildlife for food, pets, and traditional medicine compound these routes of transmission and closely track deforestation.” One common disease vector, bats, was noted in a prescient 2018 scientific paper: deforestation often drives bats into greater contact with humans, and bats are the likely source of the current coronavirus and are a major reservoir for zoonotic diseases.

Tropical forest fires can also contribute to the emergence of new diseases not only through forest fragmentation and disturbance, but through the effects of the smoke they produce. For example, fires in Indonesia caused by slash-and-burn deforestation during an El-Niño related drought in 1997-1998, may have resulted in the emergence of the Nipah virus, which caused more than 100 deaths in nearby Malaysia. The fires on the islands of Kalimantan and Sumatra consumed more than 5 million hectares of forest, generating a regional haze that spread to peninsular Malaysia, where it inhibited agricultural yields and the fruiting of forest trees. This in turn may have reduced food sources for foraging fruit bats, leading them to seek alternative sources of food on farms, where the virus transmitted from the bats to pigs, and ultimately to humans.

Even Ebola outbreaks may be linked to deforestation and forest fragmentation, again through interactions with bats. A 2017 study in Nature suggests that recent deforestation may be the driver, and some researchers have noted deeper links to poverty and agricultural and economic policies that promote forest incursions.

Deforestation, and the human development that often follows it, can also contribute to the prevalence of existing infectious diseases, such as malaria. The Anopheles mosquito that is the primary vector of malaria flourishes in newly deforested landscapes and the standing pools of “clean, partly sunlit, and clear water with pH near neutral” that they offer. The Aedes mosquito, which transmits dengue, chikungunya and Zika viruses, also thrives in disturbed environments where there is a human presence.

What are the implications of this? A clear implication is that increased investments in forest protection and conservation may pay enormous dividends in protecting public health and economic well-being. As COVID-19 has demonstrated, the global costs of a pandemic can be enormous, dwarfing the value of entire economies. The International Monetary Fund estimates that the COVID-19 pandemic will cost the global economy $12 trillion by the end of 2021. Compared to this, the cost of reducing deforestation is a pittance. Of course, eliminating deforestation would likely not eliminate the threat of pandemics, but it could surely help to reduce the risk, alongside the irreplaceable benefits forest conservation can offer by providing habitat for biodiversity and storing vast amounts of carbon to mitigate the effects of climate change.

Strategic Objective
Biodiversity, Forestry, Health, Sustainable Land Management, Land Use, Sustainable Landscapes

Eric Haxthausen

Eric Haxthausen is an independent consultant currently working with USAID's Office of Global Climate Change to highlight the link between COVID-19 and sustainable landscapes. Eric previously served as Senior Adviser in the Office of Global Climate Change.

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