How does iodine staining aid in stool parasite identification?

• A. Increases contrast to visualize cysts/trophozoites and enhances internal structures
• B. Kills the parasites to prevent infection
• C. Stains only bacteria
• D. Replaces need for concentration

Answer: (A)

Iodine staining helps by increasing contrast on the stool smear, so parasite forms stand out against the background. Lugol’s iodine binds to components in the parasite’s cytoplasm and nuclear material, making internal features more visible. This helps reveal key details such as nuclei, chromatin patterns, and other internal structures in cysts and trophozoites, which are essential for identifying protozoan parasites under the microscope. The purpose is to enhance visualization of morphology, not to kill the organisms, not to stain bacteria specifically, and not to replace the concentration step used to enrich parasites before examination.