Emergence and re-emergence of Emerging Infectious Diseases (EIDs): Looking at "One Health" through the lens of ecology

For eons humans have altered environmental integrity and disrupted ecosystem equilibrium, bringing about abrupt changes that now rival geologic forces. The accelerated anthropogenic activities have caused havoc in ecological degradation through land use changes, deforestation, and human encroachment on nature, bringing about constant race between microbial pathogens and their hosts. It causes a cascade of changes in the complex host-pathogen interactions, leading to the emergence of zoonotic diseases like HIV, Nipah virus, and Ebola. Further, the synergistic interactions and precipitous fallouts of global environmental changes, such as global warming, climate change, and biodiversity loss, have greatly affected the ecosystem homeostasis, leading to the re-emergence of malaria and SARS-CoV-2 ravaging the human society. Looking through the ecological lens, this chapter explores how naturally attuned host-pathogen bonds are broken by humans through ecoinvasive activities, but bounce-back effects turn the victors into helpless victims to the invisible pathogenic invaders.