Despite years of ecologists warning the communities about the link between the loss or changes in biodiversity and spread of emerging diseases, there has been little attention paid to this issue before Covid-19 pandemic and its problems. Thus emerged “Coronaceous period”, named for the profound and comprehensive effects of Covid-19 on human societies, has forced researchers to contemplate the main causes of recent outbreaks and find a solution to deal with them.  





Analysis of multiple biological communities around the globe has shown the connection between biodiversity loss and disease prevalence. Studies have shown that over the past few decades, the spread of diseases such as severe acute respiratory syndrome (SARS) and avian influenza, which are transmitted from animals to humans, has increased which is most likely the result of the increasing connection between humans, wildlife and livestock, as more people migrate and live in underdeveloped areas.
The question is whether declining biodiversity associated with human expansion across rural and natural boundaries increases the range of pathogens transmittable from animals to humans. Researches confirms this theory since biodiversity loss, due to deforestation and change of land use, usually leads to the replacement of numerous species with a few ones in the natural environment, and these substituted species can eventually transmit various pathogens to humans.
Studies have shown that in this situation, the populations of mammals like bats, rodents, and various primates increase which is consistent with the pattern of Ebola outbreaks in Africa. Among wildlife creatures, bats play a key role in the evolution of coronaviruses and are the main hosts of alpha coronaviruses and beta coronaviruses, since they’ve had easily adapted to human environments, such as homes, barns, farms, and gardens, ecosystems where they have found suitable to thrive.  



One of bats tricks is to assiduously ‘mop up’ and dispose of the detritus that lies around the cells as they get older – a process known as autophagy. They also maintain their telomeres – the caps on the ends of chromosomes that gradually unravel as the years go by, leading to ageing effects or cancer. It has been discovered that bats have lost some of the genes involved in inflammation. They seem to balance their immune systems between inflammatory and anti-inflammatory responses to keep it under control.
Some scientists think bats have developed these mechanisms in order to be able to fly – they are the only mammals capable of self-propelled flight and that takes a lot of energy. When the organelles responsible for energy generation – the mitochondria – are very active, that can cause a lot of damage to DNA. Prof. Teeling’s theory – unproven as yet - is that they may have developed all these fixes to cope with that.
Bats path of evolution has resulted in their resistance, or even immunity, to viral pathogens; however, these viruses can easily attack other species, including humans. During the long process of evolution, many recombination and modifications have occurred in these viruses that increased their potential interspecies transmission capability, including one important modification to use ACE2 as a receptor in host cells.
Nevertheless, bats do harbour a huge variety of coronaviruses and are the suspected reservoir for many diseases, including Nipah and Hendra virus infections, Marburg virus disease, and strains of Influenza A virus. Other research has shown that the immediate ancestor of SARS-CoV-2 is likely to have originated in a species of bat. One possibility, therefore, is that bats passed this ancestor onto another species, where it evolved to become SARS-CoV-2, and that intermediate host then passed it to humans.
According to new researches, many factors have been involved in the occurrence of the Covid-19 pandemic: there is deforestation, changes in forest habitats, poorly regulated agricultural surfaces, and mismanaged urban growth, as well as trade, and consumption of wildlife.



Overcrowding and unmanaged waste as well as animal illness, infection, and stress all rank among the standard factory farming conditions that diminish animals’ ability to fend off diseases and enhance the inevitability of outbreaks and spread. A number of financial risks are associated with animal diseases. Outbreaks can result in costly livestock losses as a result of both infection and the intentional culling of flocks or herds as well as supply chain interruptions, cessation of import or export activity, decreased consumer demand, diminished market prices, and significant reputational damage even to farming operations whose livestock has not been directly affected. The stressful conditions in industrial production of livestock may favour the spread and outbreaks of diseases transmissible from animals to humans.
We also need a healthy immune system to overcome infectious diseases; having such an immune system capable of resisting Covid-19 is impossible without the support of diverse microbiomes. To boost the beneficial bacteria, or probiotics, in the gut, some people choose to take probiotic supplements. Researches have suggested that taking probiotics can support a healthy gut microbiome, and that it may prevent gut inflammation and other intestinal problems.
The destruction that done by humans, like unregulated urbanization, also largely affect microbial biodiversity; that is found in natural environments around us, and is crucial for training, regulating or bolstering our immune systems; they are “our old friend microbes”. Weak immune system is one of the main reasons for higher mortality rates and disease severity in patients infected by the coronavirus. But our cities often lack the needed biodiversity for supporting such microbioms. As a result, urban dwellers are far less exposed to a diversity of health-promoting microbes.
Pollution can affect the urban microbiomes too. Air pollutants can alter pollen so that it’s more likely to cause an allergic reaction. Some researchers believe that the rapid increase in non-infectious health issues, such as asthma and inflammatory bowel diseases, in urban areas also links with less exposure to such organisms and loss of microbial biodiversity.
Studies have shown an increase in disease outbreaks during the past decades, most famously Covid-19 which is apparently, directly or indirectly linked with the destruction of natural environments by human activities. It is critical that countries have the capacity to detect, assess, and respond to public health crises. There need to be more focus on nature preserving efforts addressing the cultural and economical roots of destructive behaviors, ceasing them stopping the destruction of our environment, while policy makers are to be more restrictive with rural boundaries, or else we will be seeing more outbreaks in the future.

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Citation Karjalian S, Davari H. Covid-19: how environmental degradation leads to pandemics. 2022. BoomZista for Youths, 2.