Abstract
Gut microbiota composition has been extensively studied in European and North American pediatric cohorts, as well as in rural African children. Much less attention has been paid to urban African children, whose families have transitioned to a “Western” lifestyle characterized by smaller family sizes, access to perinatal care including C-section delivery, non-traditional food sources and widespread availability of antibiotics. We analyzed fecal samples from ~200 Ethiopian children aged 2-5 years from Adama, Ethiopia, using 16S rRNA gene sequencing and shotgun metagenomics. We found that well-studied factors such as delivery mode, breastfeeding and family size have only minor effects on α-diversity, whereas household crowding (single vs. multiple rooms) and consumption of the traditional fermented cereal Eragrostis tef predict higher α-diversity. Stunted growth and absence of Helicobacter pylori infection were additional factors associated with increased fecal microbial diversity. Metagenomic profiling revealed that rural African signature genera such as Segatella and Prevotella were largely absent; instead, urban Ethiopian children displayed a high Firmicutes/Bacteroidota ratio and enrichment of metabolic pathways linked to a westernized diet, resembling European rather than rural Ethiopian children. These results indicate that an urban westernized lifestyle alters gut microbiota composition, which may be partially offset by a traditional fermented diet.

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Data availability
The sequencing data generated in this study, including metagenomic and processed 16S rRNA reads, are publicly available in the NCBI BioProject database under accession number PRJNA1345963. For metagenomic sequencing, the raw paired-end reads have been deposited without further processing. For 16S rRNA gene sequencing, the deposited data consist of the quality-filtered, merged, and chimera-free reads as provided by the sequencing facility. Source data for all figures are provided in Supplementary Data 14. Sequencing data from external resources are available under accession numbers PRJNA504891 (rural Ethiopian children) and PRJNA716780 (Italian children).
Code availability
All custom code used for data processing and figure generation is publicly available at GitHub (https://github.com/lydiakirsche/urban-ethiopian-children-microbiome) and archived on Zenodo82 (10.5281/zenodo.18231174) to ensure long-term accessibility and reproducibility.
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Acknowledgements
We are indebted to the participants of this study. We thank Lena Schultheis for help with DNA extraction. This work was supported by the Swiss National Science Foundation (Project grants 320030-236304 and 310030_192490 to A.M.), the Comprehensive Cancer Center Zürich project grant (to A.M., P.L.) the Medical Faculty of the University of Zürich (to A.M.) and the CIFAR Catalyst Fund Project CF-0533 - CP25-090 (to A.M. and M.J.B.). The sponsors had no role in the study design, data analysis or any other part of the research and manuscript submission.
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L.K. performed all metagenomic analyses, generated all figures, and contributed to manuscript writing and revision. P.L. performed QIIME2-based bioinformatics analyses and supported metagenomic data processing. M.J.B. and M.S. provided scientific guidance and critical review. A.N. coordinated patient recruitment and sample collection and contributed to data interpretation. A.M. conceived and supervised the study, secured funding, and led manuscript drafting and finalization. All authors approved the final manuscript.
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Communications Biology thanks Ching Jian, Vanja Klepac-Ceraj, Guilherme Fahur Bottino and the other anonymous reviewer(s) for their contribution to the peer review of this work. Primary handling editors: Yu-Wei Wi, Aylin Bircan, and George Inglis. A peer review file is available.
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Kirsche, L., Leary, P., Blaser, M.J. et al. Gut microbial signatures expose the westernized lifestyle of urban Ethiopian children. Commun Biol (2026). https://doi.org/10.1038/s42003-026-09639-2
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DOI: https://doi.org/10.1038/s42003-026-09639-2


