Protocol v4.0 for the Scoping Review: Documented Cases of Amphixenosis: A Scoping Review

*This is version 4.0 of the scoping review protocol* While zoonotic disease transmission (animal → human) and reverse zoonosis or zooanthroponosis (human → animal) have been studied independently, research on the bidirectional spread of diseases across human and animal populations remains poorly researched, with many studies using inconsistent labeling for the phenomenon, thus fragmenting the evidence and obscuring the real size of the issue. One of the largest research gaps noticed by the author was the lack of synthesis mapping and characterizing the documented cases of amphixenosis. To address this, our scoping review aims to synthesize the documented cases of amphixenosis in the literature and how these cases were characterized in terms of the involved pathogens, host species, geography and setting, the type of evidence reported by the authors, and the terminology a study used to describe bidirectional transmission. Ultimately, the review seeks to collate and describe cases of amphixenosis to protect the health of human and animal populations, specifically by informing future research and the surveillance and control of diseases.