Covid-19 | The environmental origins of the pandemic

Call to action 27 April 2020

In an op-ed published in Le Monde , 16 heads of French research organizations, members of the National Research Alliance for the Environment (AllEnvi*), including CIRAD’s Michel Eddi, raise the alarm on the ecological crisis revealed by the Covid-19 epidemic. They stress the role humans play in environmental degradation and highlight the link between pandemics and ecosystem degradation. All types of health are in fact linked, say the scientists, since ecosystem health includes plant, animal and human health.

The One Health multidisciplinary approach is one of CIRAD's priority research topics. Veterinarians, virologists, ecologists, epidemiologists and sociologists (among others) are working together to pinpoint the links and interactions between human, animal and ecosystem health © E. Miguel
The One Health multidisciplinary approach is one of CIRAD's priority research topics. Veterinarians, virologists, ecologists, epidemiologists and sociologists (among others) are working together to pinpoint the links and interactions between human, animal and ecosystem health © E. Miguel

Epidemics have existed in the past, but recent trends show that their number and frequency are increasing. Serge Morand, a health ecologist at CNRS and CIRAD and author of the book “La prochaine peste” (The next plague), notes that “at the global level, the number of epidemics has increased more than tenfold between 1940 and today ”. Thus although the Covid-19 epidemic is one of the few since 1940, after AIDS and Asian flu (H2N2), to have reached this global scale and become a pandemic, it may well not be the last. In an op-ed published in Le Monde on 17 April, 16 heads of French research organizations, members of the National Research Alliance for the Environment (AllEnvi), look at the causes of the proliferation of epidemics, and especially of zoonotic diseases**, and call for greater efforts towards global health, integrating the health of ecosystems (whether cultivated or natural), plants, animals and humans.

The authors underline the role played by humans in the emergence and spread of new viruses. “This is […] a human disturbance of the environment, and of the human-nature interface, […] amplified by the globalization of trade and of lifestyles, which accelerates the emergence of viruses that are harmful to human populations through recombination between viruses of different species ”.

In a globalized world, increasing human-animal contacts make the spread of emerging diseases more likely

According to the first genetic analyses of SARS-CoV2, the virus originating in a bat required an intermediate host to acquire, through recombination and mutation, the capacity to infect humans. Among the possibilities identified in the search for the intermediate host: the pangolin, a heavily poached endangered species.

This type of virus transmission is possible, but rare. However, in recent years, interactions between areas occupied by humans and natural areas have accelerated. The destruction and fragmentation of the habitats of certain species, their farming, and their illegal trafficking all increase health risks. “There are many examples, such as hunting and poaching of wild species (or even protected species), which break the barrier of food security (Ebola, SARS, Covid-19), or habitat destruction, which brings humans into proximity with endemic pathogens, such as Buruli ulcer in French Guiana, where the disease is increasingly affecting humans because of deforestation ”, say the authors.

In addition to the anthropization of areas (urbanization, transport, mining, etc.), the industrialization of agriculture, food production and livestock farming – with, in particular, the intensive use of antibiotics creating resistance in bacteria –, is also implicated in the multiplication of infectious diseases and the creation of conditions conducive to their globalization.

The impact of biodiversity loss

One of the consequences of these global changes, but also one of the causes of the spread of these pathogens, is biodiversity loss in the broad sense (ecosystems, plants, animals, etc.). This loss does not concern only the reduction in the number of wild species, but also genetic diversity within cultivated or farmed species: genetic diversity that is essential to the resilience of populations, in order to limit propagation and to facilitate individual or collective resistance to pathogens (of bacterial, viral or fungal origin). The role of natural barriers and biological diversity in regulating the transmission of pathogens should not be forgotten: “A wide diversity of potential or effective host species limits virus transmission through a dilution effect ”, say the authors.

One thing is clear: if we do not reduce human activities that are harmful to biodiversity and to landscape and environmental heterogeneity, then we will foster the conditions for the spread of new diseases. “A multidisciplinary scientific expert study, with which CIRAD is associated, at the request of the French ministries, is currently seeking to increase understanding of these complex linkages between the infectious outbreak that led to the Covid-19 pandemic and biodiversity ”, says Didier Bazile, an agroecologist at CIRAD and member of the Science Council of the Fondation pour la Recherche sur la Biodiversité (French Foundation for Biodiversity Research).

Considering humans as part of their ecosystem

To manage the ongoing crisis and to better anticipate the next one, the authors of the op-ed affirm the need to “strengthen the foundations of an ecology of health, focusing on the interdependencies between the functioning of ecosystems, sociocultural practices and the health of human, animal and plant populations taken together ”.

An interdisciplinary “One Health” approach must be implemented in a concerted manner between actors in a territory in order to foster the health of ecosystems and of the plants, animals and humans living within them, to increase their resilience and to thereby reduce the risk of new pandemics.

Read the AllEnvi op-ed, published in Le Monde on 17 April

*AllEnvi includes 12 founding members (BRGM, CEA, CIRAD, CNES, CNRS, CPU, IFREMER, INRAE, IRD, Météo-France, MNHN, Gustave Eiffel University) and 15 associated organizations.

**diseases of animal origin that can be transmitted to humans