In the middle of the coronavirus outbreak, many of us have ended up turning to nature to reduce stress, enhance mental health, and stay physically active. Human relationships with nature and ecosystems have contributed to the existence of the current pandemic in the first place. So what are we going to take away from all this?
Human activity has changed our world, from land to ocean, and has contributed to the loss of ecosystems. There is clear evidence that the development of zoonotic diseases–those that move between animals –is related to the deterioration of ecosystems and human encroachment on wildlife habitats, and the United Nations has recently connected environmental degradation to the emergence of pandemics. There are two major aspects in which our impact on the environment is increasing the possibility of pandemics, such as the recent outbreak of coronavirus.
Firstly, with human settlements increasing and land clearing for agriculture, the transition areas between different ecosystems have expanded. This leads to species from different habitats combining and engaging in new ways with each other. Such new interactions offer new ways for viruses to switch between animals, just as coronavirus did. Biodiversity loss is the second main cause for the development of the zoonotic disease.
Despite biodiversity decreasing, disease vectors–those organisms that carry and spread infectious diseases–are more likely to feed on vertebrates than other species that are no longer as common. The other species would then become the main host of the pathogen. An example of that is the increased risk of Lyme disease among people in North America. It has been shown that forest destruction has contributed to reduced vertebrate diversity and increased the spread of certain generalist species, such as the white-footed mouse, which has become the primary source of the Lyme disease-causing bacteria.
High biodiversity, on the other hand, can minimize the risk to human health. The underlying mechanism is called the “dilution effect” and acts by reducing both the relative density of animals used as a natural reservoir for pathogens and the population density of pathogen vectors (such as ticks). This greatly reduces interactions between vectors and animals that are infected with the disease.