Acid fast organism with oocyte of size 5 lam on stool examination, causing diarrhoea in HIV positive patient:
Cryptosporidium
Isospora belli
Microsoporidia
Blastocystis hominii
Ans (a) Cryptosporidium Parasite causing diarrhea on AIDS patient Parasite Site Mode of infection Oocyst Cryptosporidia Enterocyte in small intestine Ingestion of oocyst Blue spherical (= 5 mm) bodies in acid fast stain Microsporidia Intestine, Muscle, CNS Spore ingestion Spores are 2-4 pm in size with polar filaments or tubules Isospora belli Epithelial cells of small intestine Ingestion of mature oocyst Oval or flask shaped, 25 pm x 15 pm with two sporocyst and four sporozoites. Also acid fast Remo- Coccidian parasites are Isospora, Toxoplasma and Cryptosporidia Blastocytis hominis is round cell of 6-40 pm containing large membrane bound central body with nuclei in cytoplasm peripherally.