A spillover event, infection, pathogen or disease occurs when a zoonotic pathogen infects a new host species. Most often the term is used to refer to a pathogen that infects wildlife species and then “jumps” to the human population, such as an avian flu virus being transmitted to a human who then transmits it to other humans. According to the CDC, an estimated 75% of new and emerging infectious diseases in humans began in animals and then crossed over to humans, and more than half of all infectious diseases that affect people can be spread from animals
