Drivers of Viral Spillover: An Examination of How Pathogens Spread

The occurrence of viral zoonotic spillover (the transmission of viruses from animals to humans) has attracted worldwide attention due to mounting concerns regarding viral threats such as avian influenza, Hendra, monkeypox, Nipah and bat coronaviruses. It is evident that these events deviate significantly from natural occurrences, being the conflation of ecological, environmental and social factors that are profoundly altering the boundaries between the animal and human domains. Consequently, in order to comprehend both the contemporary and prospective drivers of zoonotic viral spillover, a coordinated, comprehensive global One Health response is essential. The purpose of the present review is to analyze prevailing pathways of transmission between animal reservoirs and human populations. This examination involves the analysis of historical cases, including those of SARS and Ebola, as well as recent occurrences, such as the global pandemic of SARS-CoV-2 (COVID-19). A secondary objective of this review is to comprehend the fundamental mechanisms of cross-species transmission. The development of effective strategies to mitigate the emergence of zoonotic viruses and prevent future pandemics is contingent on a robust understanding of these mechanisms. This analysis is key to identifying pandemic pathogens and preventing the spread of zoonotic viruses. In conclusion, the review provides a thorough evaluation of current global strategies to prevent the spread of zoonotic viruses, highlighting gaps in our understanding and areas for further research.