Group 1: Cases (Children with acute diarrhea)  Inclusion Criteria:  Children aged 6 months to 5 years. Acute diarrhea: defined according to WHO criteria as the "passage of loose or watery stools at least three times in a 24 h period", lasts less than 14 days, with or without fever or vomiting, but considering the importance of change in stool consistency rather than frequency, and the usefulness of parental insight in deciding whether children have diarrhea or not.  Exclusion Criteria:  Malnutrition or obesity History of antibiotic therapy in the last 72 hours. Acute diarrhea in association with systemic infections Malignancy Chronic diarrhea Autoimmune and autoinflammatory diseases. Chronic renal/liver failure Diabetes mellitus  Group 2: Controls (Healthy control children)  Inclusion Criteria:  • Healthy children aged 6 months to 5 years.  Exclusion Criteria:  Acute diarrhea Malnutrition or obesity History of antibiotic therapy in the last 72 hours. Acute diarrhea in association with systemic infections Malignancy Chronic diarrhea Autoimmune and autoinflammatory diseases. Chronic renal/liver failure Diabetes mellitus