How exceptional is COVID-19?
The vaccines to combat the current corona pandemic are on their way. But how exceptional is this virus? Can it strike again? Certainly, says alumnus and Professor of Environmental Law Jonathan Verschuuren. He has explored the phenomenon of zoonosis, viruses that jump from animals to humans. What he discovered is not entirely reassuring.
How dangerous are zoonoses?
It is estimated that mammals alone harbor at least 320,000 viruses. Only a fraction of them have been discovered: fewer than 6,000. The most recent discovery is SARS-CoV-2. However, viruses only become harmful to humans and other animal species (other than those to which the virus belongs, its reservoir) when they escape from that reservoir and spread and reproduce in all kinds of ingenious ways. The rabies virus, for example, causes dogs to bite uncontrollably, enabling the virus to spread, the SARS-CoV-2 virus hijacks the RNA material in human cells, enabling it to rapidly multiply, and the influenza virus continually mutates to bypass the infected person's immune system.
From this perspective, the current coronavirus is in fact a relatively friendly virus
I have not discovered all this by myself, but it is largely taken from the book Spillover (published in Dutch under the title Van dier naar mens by Atlas Contact) by the American science journalist David Quammen. Although this book is from 2012, it is incredibly topical. Shockingly so, because Quammen, like numerous scientists before him, fairly accurately predicted as early as in 2012 what we are experiencing right now. He even refers to a wet market in China, where wild animals are sold for food, as a place of origin and to a coronavirus as a likely candidate for the next pandemic. Shocking also because the book makes you realize that we have been quite lucky that it turned out to be SARS-CoV-2: there are also viruses that show mortality rates of 70% or even 100%. From this perspective, the current coronavirus is in fact a relatively friendly virus.
Is the threat of zoonoses increasing?
The number of zoonoses has increased strongly in the past few decades. The most notorious example is the Hiv-1 virus that causes AIDS, which has a mortality rate of 100% if left untreated. So far, an estimated 39 million people have died and there are still about 38 million infected people. But we have also had SARS, MERS, Marburg, Nipah, Ebola, Hanta, etcetera.
The increase in the number of infectious diseases originating in animals is attributed to three factors. First of all, humans are increasingly encroaching on ecosystems, in particular the habitats of reservoir species. It will be clear that slaughtering wild animals for consumption is a potentially life-threatening activity.
Second, humans increasingly live in close proximity with pigs, cows, chickens, and other animals raised for human consumption. These are all potentially susceptible hosts.
Zoonoses have become an environmental problem
Third, the human population has exploded over the last century: from 2 billion in 1927 to 7.5 billion now, most of them living closely together in urban areas. What is more, many of these people are also travel addicts and globalization has further simplified the spread of viruses.
It is expected that a fourth factor will play an important role in the increased emergence of zoonoses, and that is climate change. Ecosystems change as a result of climate change, and it is likely that viruses, too, will go on a ramble with their reservoir or host.
What can we do about it?
The above shows that zoonoses have become an environmental problem. My field, that of environmental law, could play a role in preventing or, in any case, slowing down the spread of dangerous infectious diseases.
It will be clear that preventing cross-species transmissions is the best source-oriented measure. A better protection of nature conservation areas, combating poaching, banning the trade in bush meat, and limiting the trade in wild animals are obvious measures for which legal instruments in many cases already exist. These instruments will have to be tightened and will have to be better enforced.
In nature, everything is interconnected
In addition, the way in which we keep animals needs to be reconsidered, too. The questions is whether the current approach to prevent illnesses like swine flu, bird flu, and Q fever is sustainable. I see this as another argument, besides air, soil, and water pollution and climate change, to discourage the production and consumption of meat through regulation.
Air pollution also seems to play a role, at least for Covid-19. Research has now shown a clear link between the degree of nitrogen deposition in an area and the number of fatalities, in Italy/Spain/France/Germany as well as in England. The hypothesis is that lungs damaged by nitrogen are less resistant to this disease. Particulate matter also seems to play a role. Researchers in the United States and Italy have discovered that the virus uses suspended particulates as vectors and can thus easily spread. These studies explain why areas with serious nitrogen and particulate pollution, including the east of the province of North Brabant with its high livestock density, have been severely affected. Therefore, air quality regulation is very relevant for the prevention of diseases transmitted by viruses.
This only goes to show that, in nature, everything is interconnected.
A more detailed blog post on zoonoses by Jonathan Verschuuren was published earlier at https://www.milieurecht.nl/nieuws/corona-en-milieurecht (in Dutch).
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Date of publication: 14 December 2020