A 9 year old female patient presented with history of chronic diarrhea for 4 years. She had no pain abdomen or blood in stools. She had significant weight loss. She was previously evaluated with stool examination, upper gastrointestinal endoscopy, colonoscopy, computed tomography of abdomen, even then the etiology could not be identified. She continued to have diarrhea and weight loss and then presented to our hospital. Endoscopy demonstrated diffuse nodularity in the second part of duodenum. Tissue transglutaminase antibody for celiac disease was negative. Histopathological examination of duodenal biopsy showed multiple clumps of Giardia lamblia trophozoites which was confirmatory for chronic giardiasis. Then she was treated with oral tinidazole (2 grams, single dose) which with she had improvement in symptoms with weight gain.

Keywords: Giardiasis; Diarrhoea; Giardia Lamblia; Endoscopy; Chronic Diarrhoea.