Giardia hinders growth by disrupting nutrient metabolism independent of inflammatory enteropathy.


Giardia lamblia (Giardia) is among the most common intestinal pathogens in children in low- and middle-income countries (LMICs). Although Giardia associates with early-life linear growth restriction, mechanistic explanations for Giardia-associated growth impairments remain elusive. Unlike other intestinal pathogens associated with constrained linear growth that cause intestinal or systemic inflammation or both, Giardia seldom associates with chronic inflammation in these children. Here we leverage the MAL-ED longitudinal birth cohort and a model of Giardia mono-association in gnotobiotic and immunodeficient mice to propose an alternative pathogenesis of this parasite. In children, Giardia results in linear growth deficits and gut permeability that are dose-dependent and independent of intestinal markers of inflammation. The estimates of these findings vary between children in different MAL-ED sites. In a representative site, where Giardia associates with growth restriction, infected children demonstrate broad amino acid deficiencies, and overproduction of specific phenolic acids, byproducts of intestinal bacterial amino acid metabolism. Gnotobiotic mice require specific nutritional and environmental conditions to recapitulate these findings, and immunodeficient mice confirm a pathway independent of chronic T/B cell inflammation. Taken together, we propose a new paradigm that Giardia-mediated growth faltering is contingent upon a convergence of this intestinal protozoa with nutritional and intestinal bacterial factors.





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Publication Info

Giallourou, Natasa, Jason Arnold, Elizabeth T Rogawski McQuade, Muyiwa Awoniyi, Rose Viguna Thomas Becket, Kenneth Walsh, Jeremy Herzog, Ajay S Gulati, et al. (2023). Giardia hinders growth by disrupting nutrient metabolism independent of inflammatory enteropathy. Nature communications, 14(1). p. 2840. 10.1038/s41467-023-38363-2 Retrieved from

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Jason Arnold

Assistant Research Professor in Molecular Genetics and Microbiology

Microbial communities are present in almost all environments, and the full extent of their impact is largely unknown. Better understanding of how microorganisms interact with each other, their environment, and their hosts will provide immeasurable insights into all aspects of biomedical research.

My goal as Assistant Director in Duke Microbiome Center is to help facilitate efficient and effective study of these communities and their microbial constituents, and to develop novel techniques and approaches in order to enhance microbiome research across campus. 

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