Analysis of 65 years of work on the relationships between forests, deforestation and infectious disease emergence

The SARS-CoV-2 virus responsible for the current COVID-19 pandemic affecting the entire globe seems to have come about from a probable recombination of viruses from two different animal species, one of which is subject to illegal hunting or trade. So, as with numerous other emerging diseases that affect humans, this is a zoonosis, i.e. an infection of animal origin. In intertropical zones which are home to a wide concentration of biological diversity and where societies are still very vulnerable, some human populations are now faced with new health threats from wildlife. By cutting down trees to develop crop and livestock farming, those same communities come into contact with the microbial cycles found in large-scale forest biomes.

For all those reasons, researchers analysed 565 scientific papers that used the terms "forest", "deforestation" and "emerging infectious disease" in their titles and abstracts. They found that only 165 of them actually dealt with the relationships between forests, deforestation and emerging diseases that could provide useful information to the current debate. But how to account for such a gap? The scientists then studied the results in greater detail and concluded that a very large number of the papers actually dealt with an often tiny portion of the infectious cycle, i.e. solely with vector insects or reservoir animals, but much less frequently with their interactions with viruses, bacteria or protozoa. In addition, the vast majority of the articles did not discuss any connections with human cases. In the end, the topic of "forests, deforestation and emerging diseases" was rarely broached, even if a large number of papers stated that in their titles or abstracts. These researchers also noted a taxonomic bias in the articles since a large number of papers had to do with Lyme disease or cutaneous leishmaniasis. Most also referred to work in North America and in Central or South America.

This type of analytical review, now called "research on research", is vital to getting an objective, fact-based overview to guide research in the best way possible. The example discussed here really illustrates the importance of this type of study and highlights the fact that most studies still deal with complex topics in a very sectoral manner even when they have an initial OneHealth approach. Above and beyond that, this study demonstrates the need to broaden our knowledge of the emergence of human infectious diseases and their transmission by taking better account of environmental, and even, anthropological-sociological, economic and political components.

Reference

Jean-Francois Guégan, Ahidjo Ayouba, Julien Cappelle and Benoit de Thoisy (2020). Forests and emerging infectious diseases: unleashing the beast within. Environmental Research Letters.

About INRAE

INRAE, the National Research Institute for Agriculture, Food and Environment, is a key research and innovation player created on 1 January 2020. It is a targeted research organization resulting from the merger of INRA and IRSTEA, and is a community of 12 000 people, with 268 research, srvice and experimental units split between 18 centres throughout France. INRAE is a world leader in terms of agricultural and food science, and crop and animal science, and ranks 11th in the world for ecology-environment. It is the world's leading organization specializing in "agriculture-food-environment". INRAE intends to play a key role in the transitions required in response to the main global challenges. In the face of population growth, climate change, the increasing scarcity of resources, and declining biodiversity, the organization works to build solutions for multifunctional farming systems, quality food and sustainable resource and ecosystem management.

About CIRAD

CIRAD is the French agricultural research and international cooperation organization working for the sustainable development of tropical and Mediterranean regions. Along with its partners, it is convinced that agriculture has a central role in the major transitions required to guarantee a sustainable future for every country in the global South. Generating and sharing new knowledge, contributing to innovation processes and building the capacity and skills of stakeholders in those countries to support their sustainable development are the drivers of its operations. In particular, its activities centre on issues such as biodiversity, the agroecological transition, climate change, health (of plants, animals and ecosystems), the development of rural territories, and food systems. CIRAD works in some fifty countries on every continent, thanks to the expertise of its 1650 staff members, including 800 researchers, backed by a global network of partners.

About IRD

The French National Research Institute for Sustainable Development is an internationally recognized multidisciplinary agency that mainly works in partnership with Mediterranean and intertropical countries. IRD is also a leading French contributor to the international development agenda. It uses a unique model of equitable scientific partnership with developing countries, mainly those in intertropical zones and the Mediterranean region. IRD's priorities target the implementation, and critical analysis, of the Sustainable Development Goals (SDG) that the United Nations adopted in September 2015 to guide development policy and respond to major issues related to the global, environmental, economic, social and cultural changes affecting the planet.