Zoonosis
2020, what a year! A year, to never forget, or...? A year of records, records of global warming, but also of human disease and mental suffering. COVID-19 turned everybody’s daily routine upside down. But, there is hope. Namely, after we have beaten this rotten virus, there is hope that we don’t forget what got us in this sticky situation. That we draw lessons about why and how we got here. That we take our responsibility. That we turn to the real culprits of this pandemic.
Humans have come into increasing contact with new pathogens, thanks to the profound exploitation and colonisation of previously inaccessible nature, coupled with unhygienic circumstances, and bad sanitary conditions. This is through direct contact with sick animals (in the form of bites, scratches and wounds), or through contact with contaminated faeces or manure, or the consumption of contaminated meat (think for example of salmonella). For example, last year there were 92 counts of avian flu contaminations of humans, 76 of which took place in Vietnam.
The relations between humans and animals profoundly influence which kind of diseases we are exposed to. Since the 70s we have seen an increase of diseases jumping the species barrier, first from animals to humans: HIV, Ebola, Cholera, Legionella, SARS and now COVID-19 are all contemporary examples of *zoonosis*, the process by which pathogens jump from one species to the next. New variants of the avian flu, foot-and-mouth disease, and the African swine plague are all candidates to jump from animal to human.
In this regard, the circumstances of transmission are crucial. Not only does zoonosis take place where sanitary conditions are lacklustre, but more importantly, where nature is under pressure. On the frontier where humans encroach on nature, and where wild nature and human colonisation are in close contact.
Animal-human contact critically affects biodiversity. The expansion of land-use by humans increases the prevalence of smaller species by eradicating their predators, and the adaptations that humans make for land-use often create a hospitable climate for them, many of which are pathogen-carriers. A good example are the slash-and-burn techniques that result in a proliferation of insects such as mosquitoes. These conditions create an environment where it is easier for potential pathogen-carriers such as insects, small animals, and all kinds of parasites, to transmit the disease to humans.
This finding calls for a rethinking of how we treat nature on the frontier, but also raises thoughts about our fundamental relation towards nature as a resource. Many believe that biodiversity loss will not affect us, as long as we have a few key species to fill key roles in the ecosystem (bees for pollination, a single type of birds for the transportation of seeds, …). However, evidence suggests that by decreasing the populations of other species, the human species eventually becomes the dominant target for pathogens and diseases.
COVID-19 is but one disease out of many to have jumped from wild species to humans, and many more are still to come, at an ever accelerating rate. Let us therefore take our lessons from the pandemic and force our governments to take tangible action toward protecting and rebuilding biodiversity across the globe. The future of all life on earth, including our own, will depend on decisions to be taken right now!
On the connection between biodiversity loss and pandemics:
https://u.demog.berkeley.edu/~jrw/Biblio/Eprints/%20M-O/omran.1971.pdf
