Answer to the parasitology exercise: Cystoisospora belli
“An immature oocyst of Cystoisospora belli (formerly known as Isospora belli), containing only one sporoblast, which will eventually develop into two sporoblasts, and then begin to sporulate and become infectious.”
All coccidia (including Cystoisospora belli) will demonstrate fluorescence (without prior staining) when exposed to UV light. They will appear as bright blue structures when using an excitation filter of 330-365 nm or as green with 450-490 nm. Note: Cryptosporidium is no longer classified as coccidia (moved to gregarines) and does not exhibit autofluorescence!
