A WCS special report shows how degradation of ecological systems has significantly increased the overall risk of zoonotic disease outbreaks and has other complex effects on human health.

You can read the full report here.

The authors are WCS’s Tom Evans, Sarah Olson, James Watson, Kim Gruetzmacher, Mathieu Pruvot, Stacy Jupiter, Stephanie Wang, Tom Clements, and Katie Jung.

The report, which draws on detailed case studies, global analyses, modelling, and broad expert consensus, notes that the majority of emerging infectious disease threats are zoonotic, originate from wildlife, and often cause major social and economic impacts. Ecological degradation increases the overall risk of zoonotic disease outbreaks originating from wildlife.

The authors say the key “ingredients” that accentuate the risk of emerging infectious disease spillovers include land conversion, creation of new habitat edges, wildlife trade and consumption, and agricultural intensification especially when they are in, or linked to, areas of high biodiversity that elevate contact rates between humans and certain wildlife species.

This relationship has been shown for multiple individual diseases, in regional and global multi-disease studies, and in theoretical models, although the proportion of cases of degradation that lead to substantially increased risk is not well understood.

Degradation of ecosystems has additional complex effects, feedback loops and some notable negative impacts on many other aspects of human health, including: the prevalence of endemic zoonotic diseases; the prevalence of vector-borne and water-borne diseases; air quality; nutrition; mental health; and access to traditional medicines; as well as effects on human health through the impacts of climate change. These all in turn can contribute to local and transnational conflicts over natural resources and undermine local and international security.

The authors say that keeping ecosystems as intact as possible and avoiding the creation of high-risk-interface zones and high-risk activities that increase human wildlife contact, will help to reduce the risk to humanity from emerging zoonoses. Broader One Health approaches that address the full range of risk factors and are integrated into public health policies can have other beneficial health outcomes as well.

“Avoiding degradation, and keeping ecosystems intact should be prioritized to avoid future outbreaks,” says Tom Evans, co-author of the report and Forests and Climate Change Lead for WCS. “In addition to lowering disease spillover risk, preserving ecological integrity safeguards biodiversity and provides climate mitigation and adaptation benefits, food security, and protection of livelihoods for Indigenous Peoples.”

The report says that protecting ecological integrity should be a priority action within any comprehensive plan to avoid future zoonotic outbreaks, through actions such as spatial planning, the creation and management of effective protected areas, support to ecosystem management by Indigenous Peoples and local communities, and policies to minimize threats caused by particular economic sectors.

Other critical measures in addition to protecting ecological integrity include closing commercial wildlife markets and commercial wildlife trade for human consumption, especially of birds and mammals; building disease surveillance and response systems; providing global access to health care; and mitigating disease risks associated with domestic animals.

In addition to lowering disease spillover risk, avoiding environmental degradation has many related benefits, including: climate change mitigation; climate change adaptation and

environmental resilience; maintenance of watersheds and rainfall patterns; biodiversity conservation; enhancing food security, protection of the homelands, livelihoods and cultures of Indigenous Peoples and local communities; and conflict mitigation, stabilization and security.