<unk> , also known as pathogen<unk>  and<unk>  event, occurs when a reservoir population with a high pathogen prevalence comes into contact with a novel host population. The pathogen is transmitted from the reservoir population and may or may not be transmitted within the host population.
Spillover infection
Breakthrough infection
Reverse zoonosis
Vaccine shedding
Epizootic
Vaccine resistance
Subclinical infection
Intentional contagion of infection