Reevaluating the Role of Amphixenosis in One Health

The One Health concept has increasingly recognized the interconnectedness of human, animal, and environmental health. While cases of bidirectional human-animal disease transmission have been documented with pathogens such as SARS-CoV-2 and Streptococcus zooepidemicus, there remains a lack of a widely adopted dedicated classification term. Existing terminologies (e.g., zoonosis, reverse zoonosis, spillover, spillback, bidirectional transmission) are either broad, directional, event-specific, or descriptive. “Amphixenosis” may address this lack of a unified term. However, despite describing the exact phenomenon discussed earlier, bidirectional transmission is often described under broader terminology and the term is rarely used. To address this, our perspective proposes the consideration of “amphixenosis” as a dedicated term for connected bidirectional human-animal transmission while also proposing preliminary operational criteria. Greater use of a dedicated term could enhance conceptual clarity, communication, literature retrieval, and classification within One Health.