This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Parasitology Pa 1 (Protozoology), Subject name: Microbiology
[{'content': '24 yrs old AIDS patient develops chronic abdominal pain, low grade fever, diarrhea, and malabsorption. Oocyst demonstrated in stool. Likely cause of his diarrhea is - \nSelect and explain. \nA. E. histolytica, B. Giardia, C. Trichomonas, D. Isospora belli', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Option 4 The most common oppounistic Protozoa infections in untreated AIDS patients include the following: Toxoplasma gondii, Isospora belli, Cryptosporidium species. Clinical feature of Isospora belli: fever, abdomen pain, watery nonbloody diarrhea. Disease is more severe in HIV patients resembling cryptosporidiosis. Wet mount or modified Z.N. staining (0.1 - 1% H2SO4) can be done for demonstration of oocysts of Isospora belli. Image: Isospora belli: 23-36 mm in size, oval, uniformly acid fast (1% H2SO4), contains two sporocyst each bearing four sporozoites. option 1 ,2 Oocyst are not seen in case of E. histolytica and Giardia option 3 Trichomonas cause vaginal infection', 'role': 'assistant'}]