- Kinyoun stain positive and clinical features like diarrhea in a immunocompromised individual highly suggestive of organism - Cryptosporidium parvum. - Its oocyst is of size 2-6 micron and it is pink coloured. - Cryptosporidium, microsporidia, and Isospora belli are the most common oppounistic protozoa that infect the GI tract and cause diarrhoea in HIV-infected patients. - Diarrhoea is accompanied by crampy abdominal pain, nausea and/or vomiting. - Diagnosis- stool Cryptosporidium examination or biopsy of the small intestine. - Diarrhoea is noninflammatory, and the characteristic finding is the presence of oocysts that stain with acid-fast dyes. - Treatment: - 2000 mg/d of nitazoxanide (NTZ)