A patient with chronic diarrhoea shows pear-shaped flagellated trophozoites with two nuclei and a ventral disc in stool. Which diagnostic test is most sensitive when cyst shedding is intermittent?

A pig farmer presents with mucoid, bloody diarrhoea. Microscopy reveals large ciliated trophozoites with a peristome and kidney-shaped macronucleus. What is the likely pathology?

A hospital outbreak of watery diarrhoea occurs among immunocompromised patients. Modified acid-fast staining reveals small red spherical oocysts. Which control measure is most effective?

A woman presents with vaginal itching and frothy discharge. Wet mount shows motile flagellated protozoa lacking a cyst stage. What feature differentiates this organism from intestinal protozoa?

A stool sample from a healthy individual shows cysts with eight nuclei but no evidence of disease. Which organism is most likely?

A child presents with profuse watery diarrhoea. Acid-fast stain shows oocysts larger than Cryptosporidium but smaller than Isospora. What is the causative agent?

A 25-year-old woman develops diarrhoea after antibiotic therapy. Cysts with a large glycogen vacuole and eccentric karyosome are seen. Which organism is most consistent?

A 5-year-old child has foul-smelling stools and weight loss. Microscopy reveals cysts with four nuclei and axonemes. Which structure is responsible for intestinal attachment?

A laboratory technician finds oval oocysts measuring 20–30 µm containing two sporocysts in a stool sample from an AIDS patient. Which protozoan is identified?

During a parasitology practical, students observe sluggishly motile amoebae with no ingested RBCs. The specimen came from a healthy carrier. Which is most likely?

A patient with chronic diarrhoea is suspected of harbouring Giardia. Despite negative stool microscopy, what additional test confirms infection?

A man working at a daycare centre develops diarrhoea. Stool exam reveals both cysts and trophozoites with four nuclei and median bodies. Likely infection?

A stool sample shows small amoebic cysts with a large, irregular karyosome and no peripheral chromatin. The patient is asymptomatic. Which is the most likely causal organism?

A 40-year-old HIV-positive man presents with chronic watery diarrhoea. Stool microscopy shows spherical oocysts 4–6 μm in size. What is the causative agent?

During a survey, cysts with a single nucleus and lemon-shaped appearance are found in stool. What is the likely species?

A stool specimen shows amoebic cysts with four nuclei and fine peripheral chromatin. The patient has dysentery. Which organism is most consistent?

A patient complains of flatulence and greasy stools after camping. Stool exam reveals oval cysts with axonemes. Which mode of transmission applies?

A microbiologist examines dental plaque and finds motile amoebae without cysts. Which species is most likely?

A 6-year-old boy presents with watery diarrhoea after exposure to puppies. Oocysts 4–6 μm are detected by acid-fast stain. What is the most likely source of infection?