Westernization shapes protist–microbiota interactions
The gut microbiota represents a key interface within the One Health framework, linking humans, companion animals, and shared environments through continuous microbial exchange. While bacterial communities have been extensively studied, intestinal protists remain comparatively overlooked, particularly in integrated human-animal systems. Here, we used a paired dog-owner design across a Westernization gradient to investigate how modernization shapes intestinal protist occurrence, genetic diversity, and associations with the gut bacteriome. We analyzed newly collected samples from rural and urban Romanian populations and integrated them with a harmonized re-analysis of Czech cohorts representing a more Westernized setting. Protist occurrence showed clear taxon- and host-specific patterns. In humans, Blastocystis sp., Giardia intestinalis, and Entamoeba spp. declined significantly with increasing Westernization, whereas Dientamoeba fragilis showed no association. In dogs, gradient-related patterns were weaker. Blastocystis displayed the highest genetic diversity, particularly in dogs, with multiple subtypes including those associated with non-human hosts. Limited subtypes overlap between dogs and owners suggests a dominant role of shared environmental exposure rather than direct transmission. Across both hosts, rural populations exhibited higher bacterial diversity and lower inter-individual variability than urban populations. Blastocystis and Giardia were associated with increased bacterial diversity in humans, whereas Dientamoeba showed no consistent relationship; in dogs, these associations were weaker. Together, these findings demonstrate that intestinal protists respond non-uniformly to Westernization and highlight the gut as a multi-kingdom ecosystem structured by shared environmental context across human–animal systems.
The gut microbiota represents a key interface within the One Health framework, linking humans, companion animals, and shared environments through continuous microbial exchange. While bacterial communities have been extensively studied, intestinal protists remain comparatively overlooked, particularly in integrated human-animal systems. Here, we used a paired dog-owner design across a Westernization gradient to investigate how modernization shapes intestinal protist occurrence, genetic diversity, and associations with the gut bacteriome. We analyzed newly collected samples from rural and urban Romanian populations and integrated them with a harmonized re-analysis of Czech cohorts representing a more Westernized setting. Protist occurrence showed clear taxon- and host-specific patterns. In humans, Blastocystis sp., Giardia intestinalis, and Entamoeba spp. declined significantly with increasing Westernization, whereas Dientamoeba fragilis showed no association. In dogs, gradient-related patterns were weaker. Blastocystis displayed the highest genetic diversity, particularly in dogs, with multiple subtypes including those associated with non-human hosts. Limited subtypes overlap between dogs and owners suggests a dominant role of shared environmental exposure rather than direct transmission. Across both hosts, rural populations exhibited higher bacterial diversity and lower inter-individual variability than urban populations. Blastocystis and Giardia were associated with increased bacterial diversity in humans, whereas Dientamoeba showed no consistent relationship; in dogs, these associations were weaker. Together, these findings demonstrate that intestinal protists respond non-uniformly to Westernization and highlight the gut as a multi-kingdom ecosystem structured by shared environmental context across human–animal systems.
institute of vertberate biology