Immunological and metabolic profiles associated with active Giardia intestinalis infection in adults with metabolic disorders: an exploratory analysis

Background Giardiasis may present with nonspecific gastrointestinal symptoms, and conventional diagnostic approaches may not fully capture host-response differences in clinically complex patients. This study characterized immunological and metabolic measurements associated with active G. intestinalis infection in adults with metabolic disorders and examined their differences according to infection status and treatment stage. An exploratory secondary analysis assessed whether selected variables could jointly discriminate infection status. Methods In this prospective observational study, 84 adults with metabolic disorders aged 40–65 years were included at baseline and classified according to G. intestinalis infection status; 80 participants were included in the final analytical sample. Anti- Giardia IgM and IgG, multiplex cytokines, chemokines and growth factors, anthropometric measures, and metabolic parameters were assessed. Differences according to infection status and treatment stage were examined using non-parametric tests, Spearman correlations, and logistic regression. Selected variables were subsequently evaluated using multivariable logistic regression and receiver operating characteristic (ROC) analysis. Internal model performance was assessed using bootstrap resampling and stratified 10-fold cross-validation within the study cohort. Results Active G. intestinalis infection was associated with lower glucose, BMI, and HOMA-IR values and with differences in selected inflammatory mediators. IgM, IL-12p40, IL-8, RANTES, and IL-2R were among the variables associated with infection status in regression analyses. An exploratory integrated model including glucose, BMI, IgM, RANTES, IL-12p40, and IL-2R showed an apparent AUC of 0.953. Internal performance assessment using bootstrap resampling and stratified 10-fold cross-validation yielded similar estimates within the study cohort. Differences in apparent AUC between the integrated, immunological, and metabolic models were interpreted descriptively because no formal statistical comparison of ROC curves was performed. Conclusions In this study population, active G. intestinalis infection was associated with distinct immunological and metabolic patterns. The exploratory multivariable analysis identified a combination of immunological and metabolic variables with high apparent discriminatory performance within the present cohort. These findings are hypothesis-generating, and the identified predictor combination requires evaluation in substantially larger independent cohorts with prospective model development and external validation before its predictive or clinical utility can be determined.