In the past two decades, the incidence of pandemic viral outbreaks increased dramatically, such as Severe Acute Respiratory Syndrome (SARS; SARS-CoV) that broke out during 2002 in South China. Scientists suspected that bats transmitted this virus to humans through a transient host—civet cats. In 2012, a pandemic outbreak of Middle Eastern Respiratory Syndrome (MERS; MERS-CoV) appeared to arise through a transmission from bats through camels to humans. The first infection with MERS was in Saudi Arabia. Today, the world is witnessing the pandemic outbreak of coronavirus Covid-19 that started in Wuhan China at a fish market with suspected transmission from bat to humans through pangolin after undergoing mutations. All of these viruses belong to the family of Coronaviridae that contains ribonucleic acid-type viruses (RNA-viruses) known for their high mutation rates. Thus, these viruses can be easily transformed within a species from non-infectious to infectious and contagious.
With these pandemic outbreaks that have caused colossal economic losses leading to economic recession with its all repercussions, some questions arise. First, why is this high incidence of pandemic outbreaks taking place? Secondly, have humans encroached the vital space of wildlife? For example, did bats encroach on the human habitat or vice versa?
These two questions are interrelated. One inherent component to these RNA-viruses is their ability to mutate rapidly. However, like any other viruses, these non-living particles require a host to multiply and propagate, and that host can create an environment or medium that might trigger changes in the viral genome that trigger a transition from non-infectious to an infectious in humans. For example, temperature, pH, the characteristics of enzymes within the cells of the transient host and other factors might prompt some alterations in gene and protein expressions of the RNA-viruses, especially changes related to spike proteins, which are found on the outside of the virus and will bind to receptors of human lungs cells. That process enables the infiltration of these viruses into the lung cells, which leads to the alteration of this vital organ. This lung malfunction increases through inflammation and perfusion of fluids into the lungs, and the decrease in oxygen supply will launch a domino effect that inflicts serious physiological disruptions in other vital organs, such as the liver and the kidney. The combined assault on organs can end in death.
Increasing n encounters between infectious viruses and humans creates a growing public-health risk, which is induced by human behavior. We are destroying the natural habitats for many wild species, including bats, at a very high pace. Scientist estimate that natural resources are used at a rate of 175% from their potential. The habitat of animals will shrink, thereby reducing the distances to human residential and urban areas. For example, research suggests that human exposure to bats is increasing. These animals underwent coevolution with viruses over millions of years, so they developed adequate immune responses to these viruses, but the transmission of viruses to humans or other species naïve to these viruses might trigger serious diseases.
Many factors might play a role in the seemingly increasing frequency of pandemics. One of these factors is climate change, which increases the incidence of flooding and cyclones, which could increase the outbreak of some bacterial disease, such leptospirosis, or viral diseases, such as West Nile virus. Second, the change in temperature patterns, especially the increase in temperature, may be favorable for the development of certain diseases.
Moreover, the tremendous expansion of urban sprawl—fragmenting natural habitats and increasing pollution—contributes to compromising the immune system of wild animals, such as bats, living in urban and suburban area. This compromise in the immune system of urban wildlife results in wild animals spreading more viruses in these densely human-populated areas.
A huge lack of knowledge of wildlife viruses compounds the pandemic challenge. Currently, scientists know about only 1%of wildlife viruses. Therefore, it is essential to invest more in understanding these microscopic enemies that can cost human economies trillion of dollars, which happened recently with influenza. On the other hand, giving wildlife room to roam costs much less. It is time to wisely use the ecosystem services in a sustainable fashion and not overuse it. Economic experts anticipate an $8 trillion cost due to the Covid-19 pandemic outbreak and expansion, and tens of thousands of human lives are already claimed.
Our mother nature generously provides us with many vital services—all free of cost. If we continue misusing our world, it will hit back in many forms, including cyclones, pandemic infectious disease and more. Humankind must be cautious and vigilant or our smooth sustainable existence will be at the stake.
Bachir Abi Salloum, PhD in Agricultural Sciences
Adjunct Faculty of Viral Infectious Diseases, Epidemiology, Endocrinology at
LU, UOB