**1. Introduction**

On February 11, 2020, World Health Organization (WHO) named COVID-19 a new severe acute respiratory syndrome, provoked by a new coronavirus isolated a month earlier. WHO declared this disease an international health emergency and the virus, SARS-CoV-2, has entered to take part of our daily lives. Life as we know it has changed rapidly, and the evolving pandemic scenario has made us realize how deep globalization is. Every country around the world willing to curb the spread of COVID-19 has placed precautionary principle at the core of public

health policies. At EU level, precautionary principle is defined as principle enabling "decision-makers to adopt precautionary measures when scientific evidence about an environmental or human health hazard is uncertain and stakes are high" [1]. In the case of SARS-CoV-2, reflecting on human health means reflecting on environmental conditions as well, given the strong interconnection between human beings and their surrounding environment. Indeed, even if the whole causal sequence between ecological changes and emerging zoonosis is not thoroughly clear, there is strong evidence of their bonding. Especially, when we consider that the epoch we are living in could be termed 'Anthropocene', since the devastating impact of human activity on our planet. This much is clear: addressing pandemic tightly as a national healthcare issue would prove to be unsuccessful, likewise conceiving it as a merely human health matter. Indeed, multidimensional connection between human health and environment is nowadays very clear and we have a pressing need to choose an ethical and legal approach that takes due account of this link.

## **2. Zoonosis as an environmental and human health crisis**

SARS-CoV-2 belongs to the family of coronaviruses, whose preferred hosts in nature are various animal species [2], and which were identified in human beings for the first time in 1966 [3, 4]. In the event of transmission of disease or infection from vertebrate animals to humans, we refer to "zoonosis". Nowadays we know over 200 types of zoonoses, whose conspicuous portion consists of existing diseases in humans (rabies, AIDS, etc.) [5]. The possibility of infection and disease transmission from other vertebrates to human being testifies to the belonging of humans to the animal kingdom, as a memorandum of the interdependence amongst animal species.

When it comes to zoonosis, infectious disease is due to a pathogen (such as a bacterium, virus, parasite or prion) affecting a reservoir animal, which actually can remain undamaged by this infective agent. Pathogens hosted by reservoir animals may need an intermediate to gain access to humans, and this intermediate serves as an amplifier of the infectious strength [6]. That is, sometimes the last victim in a zoonotic infection chain requires higher dose of pathogens or prolonged contact to get infected [7]. A differentiated infection threshold ensures significant protection to humans against viruses, but more considerable degree of protection is ensured by high biodiversity and an unhindered ecosystem. In such a context, possibility of contact and transmission decrease sharply. Pathogens are definitely unconscious, therefore their transfer responds to an evolutionary mechanism: they move from one host to another since this solution, randomly found, turned out to be successful from both reproductive and survival standpoint. Amongst pathogens, viruses are undoubtedly the most troubling due to their evolutionary rapidity, flexibility, and resulting mortality rate. Moreover, "viruses have no locomotion yet many of them have traveled around the world" [8].

Describing zoonotic mechanism requires also to stress the difference between spillover and emerging infectious diseases. Spillover indicates the point at which a pathogen moves from one animal species to another; while an emerging infectious disease is the one which has been increasing after introduced in a specific population. These notions are clearly linked, especially if we consider that, under ordinary conditions, infectious diseases are natural events, which bond individuals and species in their ecosystems. Cross-species transmission is not rare, but rarely it is the result of chance. In fact, last decades have been heavily characterized by an increasing disruptive human activity perpetrated on the environment: Transforming natural habitats, altering ecosystems, reducing biodiversity and damaging patterns of interactions between different species [9–12]. Climate change, deforestation,

#### *Why a Bioethical Approach is Needed in Addressing Health Risks Stemming from Pandemics... DOI: http://dx.doi.org/10.5772/intechopen.98359*

overfishing, natural resources extraction, intensive farming, wildlife poaching and trade are all key drivers of increased rates of zoonotic emerging diseases. Human communities find themselves living near wildlife ever more frequently, and wildlife turns out to be often potential host of pathogens responsible for transmitting infection [10]. So, it is hardly surprising that zoonosis has been indicated as a word of the future, expected to become quite common in this century [13]. Environmental devastation provides a suitable growth medium for interspecies viral transmission, a perfect trampoline for "host jump". Three core elements have to be considered. The first is the difference between past and present human activity: nowadays Earth hosts 7 billion people, equipped with the most up to date technologies. This set far exceeds the absorption capacity of Nature. The second core element regards the notion of "virosphere", that is the remarkable viral diversity existing on our planet - a group of living organisms of exceptional size [14]. The third core element consists of the overlapping of the first two: Where wildlife and natural habitats are destroyed, there is an impressive amount of unknown pathogens prompt to assure their own survival by affecting new kind of hosts. Consequently, when we consider zoonoses, we can safely affirm that we face both an ecological and a health crisis.

Within this framework, SARS-CoV-2 is no exception. Current pandemic is the third of zoonotic origin in the twenty-first century, after severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-Cov) [15]. Even if the animal species at the origin of COVID-19 outbreak has yet to be determined, knowledge gained on SARS-CoV and MERS-CoV has enables scientists to identify bats as likely reservoirs of SARS-CoV-2 [2, 11, 16]. Evidences suggest that pangolins might have served as amplifiers, in a sequence of spillover from bats to pangolins and finally to humans [11, 17].
