A patient presents with diarrhea and GI disturbance, analysis of stool on wet mount shows motile protozoa without RBCs and pus cells. The diagnosis is -

Option 1 Balantidium coli may cause Dysentery: Ulcers mimic amebic ulcers but never invade muscular layer. Option 2 1. Giardia causes noninvasive diarrhea so there will be no RBCs. 2. In acute giardiasis, diarrhea is often foul smelling with fat and mucus without blood. It causes GI disturbances 3. Microscopy: Demonstration of either trophozoites (active infection) or cyst (carrier) sample by iodine and saline wet mount preparations. Option 3 T. hominis- non pathogenic , maybe associated with diarrhoeagenic stools Option 4 E. histolytica cause Dysentery (RBCs in stool).