These diseases and their pathogens, with the unsuspecting support of humans and our global activities, all have been involved in microbial invasions of sorts. The transportation and sale of live bait is the latest example of a seemingly innocent human activity that may be responsible for spreading such diseases with dramatic ecological consequences.
Evidence for this comes from the genetic analysis of an emerging virus that has been implicated as a cause of infectious disease in amphibian populations in the western U.S. The genetic study indicates that the virus may have been transmitted to remote locations through the vector of live bait infected salamanders being distributed and introduced to uncontaminated environments by fishermen and interstate bait wholesalers.
A research article by a team (see end of release) headed by Arizona State University ecologist James Collins forthcoming in the Journal of Molecular Ecology finds that the wild incidences of a devastating iridovirus in Arizona and Colorado are all very similar genetically, indicating a recently emerged or introduced strain. The strain also closely matches viruses isolated from imported salamanders found in bait shops, indicating a possible source for the pathogen's introduction.
The finding further exposes a complex picture of how emerging or invasive diseases are involved in amphibian decline -- the ongoing global disappearance of a broad group of animals -- and is additional evidence for how human activities such as farming and trade in live animals or biological products are affecting ecologies globally.