Pathways and Vectors
Species can be transferred either intentionally or accidentally from one ecosystem to another through such phenomenon as wind and sea currents, and through human activity. These are termed "Pathways". We cannot judge these transfers as intrinsically good or bad until the results are observed. It is only when the economy, native environment or human health is threatened that we can label the newly introduced species as Invasive.
One group of pathways, i.e., the pathways that result in the transfer of diseases and parasites that harm humans, plants, or animals are uniquely identified as "vectors". Unfortunately, one of the most recent challenges faced by scientists today is the possibility of harmful disease-causing pathogens that may be introduced deliberately by the vector of bioterrorism. Fortunately, the same methods now being developed by scientists to identify and control invasive species in general can be applied, if necessary, to manage and control intentional disease outbreaks.