A 4 year old child presents with acute watery diarrhea and abdominal cramps. Stool microscopy reveals trophozoites with falling leaf motility. The etiological agent is ?

Ans. is 'b' i.e., Giardia lamblia In acute giardiasis trophozoites show the typical "falling-leaf" motility in wet mount examination of faeces. Diagnosis of giardiasis? The gold-standard for diagnosis of giardiasis is microscopic demonstration of trophozoite or cyst or both in faeces. In acute giardiasis trophozoites show the typical "falling-leaf" motility in wet mount examination of faeces. The characteristic shape and two nuclei are seen after staining a thin faecal smear with Field's stain. Trophozoites are also present in duodenal fluid. Duodenal fluid can be either aspirated or obtained by "String test" (Enterotest) for examination. Cysts of G. lamblia are often shed in the faeces in "Showers", meaning that many cytes may be passed on a day and none on the other. Hence, to detect cyst-passers multiple-sample are to be examined, preferably following concentration techniques like zinc sulphate floatation or formal detergent concentration technique.