Biodiversity and Pandemics
Yesterday, I received an email with some updates on articles from a Belgian magazine. Amongst the titles, there was one that captured me and it said “WWF: there is a link between the destruction of nature and the coronavirus”. I was intrigued so I started reading.
The article refers to a report released by WWF Italy which you can find here, however, I will give you some interesting highlights from the report below.
The Virus: where did it come from?
Many emerging diseases - such as Ebola, AIDS, SARS, avian influenza, swine flu and today the new coronavirus are not random catastrophic events, but the consequence of our impact on natural ecosystems.
Human beings and their activities have significantly altered 75% of the land and 66% of the oceans, changing the planet to such an extent as to determine the birth of a new era called the “Anthropocene”.
Many pandemics of the last decades have originated in the markets of Asian or African metropolises where the illegal or uncontrolled trade of live wild animals, such as monkeys, bats, snakes, pangolins, and many other reptiles, mammals and birds. These activities create dangerous opportunities for contact between humans and the diseases of these organisms, creating the conditions for the development of old and new infectious diseases that can be transmitted from animals to humans.
The SARS-CoV-2 contagion (the base for the COVID-19 virus) in human beings appears to have originated in the large animal market in Wuhan, in the Chinese province of Hubei, with an evident outbreak in December 2019.
In truth, the Wuhan market does not appear to have been the only source of the outbreak which, as suggested by a study by the Zhejiang University of Hangzhou, could have also occurred in other places. Analysis of the RNA sequences of the virus indicates that there are two 'sibling' strains of the SARS-CoV2 virus, called Type I and Type II. The latter seems to have originated in the Wuhan market, while Type I does not yet have a clear origin.
The outbreak among humans of viruses previously circulating only in the animal world is a phenomenon widely known as spillover (in ecology and epidemiology the term indicates the moment in which a pathogen passes from one species to another) and is thought to be at the origin of the new coronavirus.
It is still uncertain which animal species may have acted as intermediate hosts in the case of the SARS-CoV-2, also because the city market of Wuhan, where the Type II strain evolved from, sells and slaughters on-site live wild animals of many different species of birds and mammals.
To understand the evolution of the virus and its passage through different hosts, it is necessary to know that every time the virus infects a host, it can mix its genetic heritage with that of other viruses present in the host (such as influenza viruses) or rapidly mutate (such as RNA viruses). Then it reproduces at the expense of the cell that it infects and abandons the host, but with a different genetic makeup, sometimes allowing it to infect new species. This way, by analysing the DNA or RNA of the virus, it is possible to “trace” its passage through different species.
There are theories from Chinese researchers suggesting that pangolins might have helped spread the virus, however, it is not full proof. Research at the University of Rome is suggesting that the epidemic might have originated from bats sold alive and slaughtered at the Chinese markets.
However, to date, it remains to be confirmed where the virus initiated from exactly. Several pieces of research show that the widespread diffusion of this new pathology might be linked to the often illegal or uncontrolled trade of live wild animals and their body parts. This practice is a vehicle for old, and new zoonoses, and increases the risk of pandemics that can have enormous health, social as well as economic impacts on all the communities involved.
From Animals to Humans
Human diseases can be generated by a great diversity of microorganisms, but those that currently spark the greatest interest are those with a viral origin and especially zoonoses, also called zoonotic diseases.
A zoonosis is any disease or infection that is naturally transmissible from vertebrate animals to humans. These diseases include a diverse group of infections, which can be caused by viruses, bacteria, fungi, other organisms or abnormal protein agents (prions). The known zoonoses are very numerous - over 200 according to the WHO - and their study constitutes one of the areas of greatest interest in human and veterinary medicine. Rabies, leptospirosis, anthrax, SARS, MERS, yellow fever, dengue, HIV, Ebola, Chikungunya and Coronaviruses are all zoonotic, but also the most widespread flu, just to name a few.
As with viruses, the moment when a pathogen passes from one host species to another is called “spillover”.
The transmission can take place by direct contact, as in the case of rabies, through other vector organisms, such as different insects such as mosquitos or ticks, or other environmental and food vehicles. For human beings, the most dangerous zoonoses are those transmitted not only by other animals but those which subsequently adapt to our species, allowing, as in the case of the Ebola virus, for the disease to spread between human beings. Zoonoses that manage to transmit from human to human are the most dangerous because with billions of human beings that gather, socialize and travel they can generate epidemics if not pandemics, enhanced by the growing globalization.
Of all emerging diseases, zoonoses of wildlife origin could represent the most significant threat to the health of the world population in the future.
75% of human diseases known to date stem from animals and 60% of emerging diseases have been transmitted by wild animals. Zoonoses each year cause around one billion cases of disease and millions of deaths.
From Damage of ecosystems to the risks to our health
It is now established that natural ecosystems, whether they are temperate or tropical forests, river basins or coastal wetlands, grasslands or peatlands, have a crucial role in supporting and nourishing life, including that of our species.
In-depth research has recently linked the important role of altering ecosystems to the development and spread of infectious diseases such as zoonoses.
Scientists around the world are aware that one of the causes of the spread of emerging infectious diseases (such as Ebola, Marburg Haemorrhagic Fever, SARS, MERS, Rift Valley Fever, Zika and many others) includes the loss of habitats, the creation of artificial environments, the manipulation and trade of wild animals and more generally the destruction of biodiversity.
Our destructive action on the complex dynamic balances of the biosphere as well as our intervention on ecosystems - on the functioning of which we still know very little - can lead to consequences that have a direct impact on our well-being and in particular on our health.
The degraded suburbs without green spaces present in many cities are the perfect cradle for dangerous diseases and the transmission of zoonoses; while the widespread use of irrigation systems, channels and dams allow the reproduction of dangerous vectors such as mosquitoes.
The complex but alarming relationship between the destruction of ecosystems (and the biological mechanisms that regulate them) and the spread of infectious diseases can be better understood if we look at a series of specific cases already illustrated in the first report on the state of the world's ecosystems, published in 2005, and sponsored by the United Nations, the Millennium Ecosystem Assessment.
Deforestation has increased the risk of malaria in Africa and South America. This is largely due to the disruption of the ecological balance that reduces the spread of mosquitoes.
Irrigated rice fields facilitate the reproduction of mosquitoes, which in turn spread serious diseases such as malaria, lymphatic filariasis, Japanese encephalitis and other pathologies.
Habitat fragmentation in North America, and the consequent loss of biodiversity, have increased the presence of a group of bacteria that cause Lyme disease, transmitted to humans through the bite of an infected tick.
The intensive use of drugs in intensive livestock breeding has led to the appearance of antibiotic-resistant strains of Salmonella, Campylobacter and Escherichia coli.
Tropical urban areas with poor water supply systems and the lack of shelter have shown to favour the dangerous and widespread transmission of dengue fever.
Unfortunately, our understanding of the interactions between ecosystem change, disease regulation and human well-being is still limited. Not only do we know very little about the diversity of microorganisms present on our planet, but we have yet to discover and therefore fully understand much of the mechanisms that regulate the relationship between them and other species, including ours.
A better understanding of how our ecosystems function - and in particular their role in defending us from the spread of diseases - is fundamental to understand the importance of protecting and managing them better; to avoid having to run for cover at a later date, to rebuild and restore balances and ecological processes crucial to our health previously destroyed.
“Unprecedented” is the adjective used in 2019 by the UN Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) to define the destructive action of man on nature. The IPBES report is the most recent and influential report on the state of planetary biodiversity. According to the report15, 75% of the terrestrial environment and about 66% of the marine environment have been modified in a significant way, with around 1 million animal and plant species finding themselves in an unprecedented risk of extinction.
According to data from the Living Planet Report prepared by WWF in 2018, in just over 40 years the abundance of vertebrate populations across the globe declined on average by 60%.
Destruction of forests and pandemics
Forests cover 31% of the planet's lands, they constitute the habitat for 80% of the Earth's biodiversity and, in various forms and particularly due to the process of photosynthesis and the absorption of CO2, contribute to mitigating climate change. They provide an infinite number of services that enable life on our planet, including not least the protection of our health.
According to most recent data, rainforests produce more than 40% of the earth’s oxygen and deforestation is one of the main causes of global warming as it produces between 12 and 20% of greenhouse gas emissions.
To date, we have lost almost half of the forest area that embraced and protected our planet. According to a study it is estimated that at the beginning of the agricultural revolution there were about 6,000 billion trees on Earth, while today there are about 3,000 billion17.
Land-use changes and destruction of natural habitats - such as tropical forests - are held responsible for at least half of emerging zoonoses.
The destruction of forests can, therefore, expose humans to new forms of contact with microbes and with the wild species that host them.
For example, in the pristine forests of West Africa live bats carrying the Ebola virus. The change of land use such as the creation of access roads to the forest, the expansion of hunting territories and the collection of wild animal meat (bushmeat), the development of villages in previously wild territories, has brought the human population into closer contact with the virus at its onset.
Wildlife trafficking, bushmeat, pandemics
The trade in wild species and direct contact with animal parts through the exchange of liquids, or other means, exposes humans to contact with viruses or other pathogens of which that animal can be a host.
The illegal killing of wild animals for food is increasingly considered by the international scientific and conservation community one of the main causes of the decline in animal populations outside and inside forests, especially in those countries where political instability is reflected in instability in the management and control of natural resources.
There is evidence that contact with wild species such as bats, Asian palm civets, monkeys and other animals (mainly birds and mammals) can lead to the onset and contribute to the spread of serious zoonoses. It is no coincidence that recurrent outbreaks of Ebola epidemics are often linked to the consumption of contaminated bushmeat (monkey meat).
Bushmeat is consumed directly in the forests but also transported to the countryside and cities. In some cases, what is considered a delicacy, as is the unfortunate case of monkey meat, follow illegal trade routes that arrive in distant countries.
In various researches carried out by TRAFFIC, the wildlife trade monitoring network, dramatic data on bushmeat consumption emerge: it has been calculated that in a single district of Kenya about 80% of families consume on average 14.1 kg of bushmeat per month, while in a rural area of Botswana 46% of families consume about 18.2 kg. In Central Africa alone, consumption goes from 1 to 3.4 million tons per year.
Bushmeat trade and consumption is far from being an exclusively African practice; it takes place in many other countries of the world. For an idea of its scale, we should consider that every year in Peru alone 28,000 monkeys are hunted and consumed. In Indonesia, as well as monkeys and other wild mammals, 25 tons of turtles are captured and exported.
Just as hunting and the consumption of bushmeat poses very serious risks to human health, the same is true of the widespread trade in wildlife and animal parts: wildlife trafficking. The cross-border trade in animals and plants is not only a primary cause of biodiversity loss, but it can also be an important mechanism for spreading zoonoses.
Wild animals of all kinds are trafficked along commercial roads that connect continents and distant countries, potentially amplifying the spread of pathogens.
Farmed or wild animals have enormous potential to transmit viruses. They can scratch, defecate, urinate, cough, contaminating each other or, more worryingly, contaminating humans. Moreover, the close proximity of different species facilitates the genetic recombination between different viruses and with it spillover, that is the ability to infect new species.
China's recent decision to ban the trade of live animals for food on its national territory represents a choice of fundamental importance, but still not sufficient.
To do: protect nature and restore the damage done
It is evident that preserving the ecosystems that are still intact, protecting the pristine areas of the planet, also by limiting accessibility, prohibiting the consumption and trafficking of wild species, favouring the natural balance of ecosystems and restoring damaged ones are among the most forward-looking choices that humanity can take.
The extraordinary web of life that supports the well-being of our species, as well as all the others, has been attacked and deteriorated by our species with such an intensity that to imagine a global future we need to intervene at a planetary level, through a new global agreement between humans and nature, we need a: New Deal for Nature & People.
This new agreement must include the need to:
halve our footprint on Nature;
stop the loss of natural habitats;
stop the extinction of living species.
Although the fundamental and main objective is still maintaining the vitality of natural systems to preserve their evolutionary capacities and their dynamics, it is also necessary to proceed with actions to restore the functions, processes and dynamics of these extraordinary systems that nature has designed in
Although the fundamental and main objective is still maintaining the vitality of natural systems to preserve their evolutionary capacities and their dynamics, it is also necessary to proceed with actions to restore the functions, processes and dynamics of these extraordinary systems that nature has designed in billions of years of evolution of life. We must start a real work of “reconstruction” of the ecosystems that we have destroyed or degraded.
Aware of this difficult challenge, the United Nations has decided to dedicate this decade to Ecosystem Restoration.
For the good of the planet and therefore for our own good, it has become an urgency and a priority not only to protect but also to restore natural balances, restoring degraded habitats. The restoration of nature and its systems is fundamental for maintaining the function of all the mechanisms of the biosphere, including those of the climate.
It all depends on us and on the choices we make.