The microbiome and non-occupational human-animal interactions: a scoping review

Human-animal interactions may impact the composition of the human microbiome. This can then influence human physical, mental, and social wellbeing. This scoping review synthesizes the literature on the impacts of intentional, non-occupational human-animal interactions on the human microbiome. Six databases (PubMed, CINAHL, PsycINFO, Web of Science, CAB Abstracts, and ProQuest Dissertations and Theses) were searched using keywords for human-animal interactions and microbiomes. Database searching resulted in 2,946 publications. Publications were screened according to the following inclusion criteria: (1) published in English, (2) peer-reviewed article or dissertation presenting empirical data, (3) studies humans engaging in intentional, non-occupational interaction with animals, and (4) compares human microbiome composition before and after human-animal interactions or compares humans that interact with animals to humans that do not interact with animals. Screening resulted in 30 relevant publications. Of these, 24 reported a significant effect of human-animal interactions on microbiome composition. However, there were notable gaps in the reporting of demographics and methodology, such as length of human-animal interaction, species of animal, and variable 16S regions of focus. To better understand the impacts of human-animal interactions on the human microbiome, future studies should include detailed reporting of both human-animal interactions and microbiome analysis methods.