In recent decades there has been a drastic increase in emerging and re-emerging viral diseases in both humans and animals. Climate change is likely causing the spread of vector arthropods and therefore diseases considered exotic until a few years ago; deforestation and urbanization contribute to accelerating this process and lead to a progressive reduction of habitat for wild animals which have then greater chances to get in contact with domestic animals and humans, along with the related pathogens of which they are reservoirs. Animals, especially synanthropic, can in turn become contaminated with human pathogens and with drugs released into the environment and act as a "mixer host" involved in their evolution and in a possible re-transmission to humans. A drastic change for the study, diagnosis and management of human and animal infectious diseases, including antibiotic resistance (AMR), becomes therefore mandatory. Current knowledge demonstrates that the dichotomy "animal pathogens-human pathogens" is an obsolete concept that, if pursued, will continue to limit the achievement of a One Health management of health. The COVID-19 pandemic has also demonstrated how important the joint efforts of human and veterinary medicine have been crucial for tracking, diagnosing, and characterizing SARS-CoV-2. The experience gained therefore guarantees a strategic model for the adoption of new measures aimed at preventing and mitigating the emergence of novel pathogens in humans and further AMR phenomena.