ABSTRACT
Emerging and re-emerging viral infections pose a constant threat, especially in healthcare settings. Viral infections can be thought of as an ecological system, like a forest or a pond, with different species competing for resources. Pandemics tend to occur when there is a disruption to this ecosystem, such as introducing a strain of virus into humans or animals that they have no immunity against. Around 60% of human infectious diseases and 75% of emerging infections are zoonotic, with two-thirds originating in wildlife. There is an ongoing risk of viral diseases as the human population continues to grow and the rate of urbanization increases. The emergence and re-emergence of viral diseases are influenced by a variety of virologic and environmental factors. These factors can be roughly categorized as affecting humans, the environment and/or ecology, and viruses. The spread of zoonotic diseases among humans can be prevented by reducing the transmission risk associated with wildlife and exotic pets through education, legislation, and behavioral change programs that target individuals at risk for exposure.