Giardia intestinalis belongs to
Giardia intestinalis synonym Giardia lamblia duodenalis belongs to order Diplomonadida in supergroup Excavata, diagnosed by binucleate trophozoite with adhesive ventral disc composed of microtubule spiral providing attachment to intestinal microvilli, four pairs of flagella, and median bodies. Inhabiting anaerobic duodenum, it lacks conventional mitochondria possessing instead microaerophilic mitosomes. Transmission occurs through quadrinucleate cysts in contaminated water causing malabsorptive diarrhea. SSU rRNA phylogeny places it among diplomonads alongside Spironucleus, distinctly separate
Ref: CDC DPDx Giardiasis Giardia intestinalis diplomonad; Harrison Principles Internal Medicine diplomonads binucleate parasite adhesive disc