Oocyst autofluorescence under UV is most helpful for differentiating Cyclospora from which group?

• A. Bacterial cysts
• B. Helminth eggs
• C. Blood cells
• D. Other Gastrointestinal protozoan oocysts

Answer: (D)

Autofluorescence under ultraviolet light is a distinctive property used to identify Cyclospora oocysts. When exposed to UV illumination, Cyclospora oocysts naturally glow, helping to set them apart from other gastrointestinal protozoan oocysts such as Cryptosporidium and Isospora in stool samples. This fluorescence is not a feature of bacterial cysts, blood cells, or helminth eggs, so the most useful differentiation is from other GI protozoan oocysts.