This abrupt change quickly leads us to underline the exceptional  character of such a crisis and qualify it as a "once in a century" crisis. While this statement was  still plausible at the time of the last disruptive pandemic in 1918, it is less believable today, as  human activities increase the frequency of outbreaks. As Professor Matthew Baylis from the  University of Liverpool states, “As in the last 20 years, we've had six significant threats - SARS,  MERS, Ebola, avian influenza and swine flu. We dodged five bullets but the sixth got us”. One of the main drivers of this phenomenon is the ever-growing impact of humans on  biodiversity. The human-induced biodiversity loss and destruction of natural habits are  gradually favouring zoonotic diseases and spill-over effects, i.e. diseases transmitted from  animals to humans. Let's take the example of city building. When a city is created, as natural  as it now seems to us, it means destroying a complex biodiversity that was previously there. 

By destroying the natural habitat, humans are creating more and more interfaces with species,  thus promoting the exchange of pathogens. But the threat does not end there. According to new research, the most resistant species to human action, such as rats and pigeons, are also  the ones most likely to transmit diseases to them. Their populations even tend to increase  when an environment changes from rural to urban, as they replace the more rare and specific  biodiversity that did not survive the change. These findings, made after analysis of more than  184 studies on a total of more than 7,000 species (BBC), underline the potential danger  associated with urbanisation. 

For instance, Ebola outbreaks in Central Africa did not create an  epidemic until Guinean citizens sought medical treatment in major cities in 2014. Once in the  city, the virus was able to flourish (Genton et al, 2014). This is all the more worrying when one  considers the large share of substandard housing in the growth of cities in developing  countries. Currently, more than one billion people are living in informal settlements, often  near cities (UN). Those settlements do not have the sanitary facilities necessary for the good  health of their population. The populations of such settlement are thus more in contact with  animals carrying contagious diseases but are also more exposed to waterborne diseases. Without any urgent change in policies, urbanisation will continue to favour outbreaks. 

The impact of humans is not only in their distribution. Indeed, man-made climate change is  also a crucial factor in the increase of outbreaks. As we warm the planet, we disrupt entire  ecosystems, forcing them to change and adapt. For instance, the new temperatures will allow more areas to be inhabited by mosquitoes transmitting diseases such as malaria or dengue  fever. It is important to note that this disease can also be transmitted between humans. Thus,  according to the World Health Organization (WHO), between 2030 and 2050, 250,000 more  people will die from mosquito-borne diseases. For instance, dengue fever has already gained  ground in recent years. In 1970, it was endemic in 9 countries, today that number has risen to  128, and projections state that it will threaten 60% of the population in 2080.

The movement of animals is therefore a pressing issue if we are to cope with this new “pandemic era” (Dr Anthony Fauci). Let's take the example we are familiar with due to the  current contact: Bats. Bats are carriers of many viruses and other pathogens. Between 1994  and 1998 at least four pathogens were transmitted to humans by bats. Not every disease  becomes a pandemic, but if the frequency of these exchanges continues to increase, the risk  of a pandemic also does.

With global warming, disruption of their environment, and natural food source cycles, bats  struggle to find food. Hence, they move closer to civilisation (Robert M Beyer, 2021). This  trend favours their contact with other animals and humans as well as increases their risk of  transmitting pathogens. To take a concrete example, in 1994, in Australia, bats moved closer  to civilisation for reasons already mentioned. By urinating in grass later ingested by horses,  these bats contaminated them with a virus that caused the death of 7 people (RollingStone). With an estimate of 1.7 million undiscovered viruses in the animal population, the movement  of animals and their increased contact with humans are cause for concern in the coming years. 

Our way of exploiting nature and organising ourselves as a society is therefore not optimal in  protecting us from epidemics, but rather increases the risk of their creation. This is a global  phenomenon that cannot be confined to specific countries. Therefore, we need to rely on  international cooperation as a foundation on which to build our resilience. At a time of  uncertainty when it is easy to turn inward, many call for greater collaboration. On 30 March  2021, world leaders joined a call led by the WHO and the European Council for an international  treaty on preventing and managing future pandemics. This treaty will aim to increase  collaboration in pandemic research and response to limit their frequency and impact. At the same time, the "One Health" approach advocated by the WHO joins and extends this  idea of international collaboration. “One Health” considers health and disease in a holistic,  interconnected way between the environment, animals and humans. Better prevention, therefore, requires a global analysis of these different sectors It advocates extensive  collaboration between sectors, for example, between industries and academics in exchanging  research and data to expand knowledge and prevention of pandemics. 

These new ways of thinking about our connection to each other and to the environment must  form the basis of our response to future pandemics if we are to limit their impact.