What stain can be used to identify schistosomiasis?

• A. HMWCK
• B. Giemsa
• C. PAS
• D. Ziehl-Neelsen

Answer: (A)

Staining to identify schistosomiasis relies on making the parasite eggs visible within tissue sections. The Periodic acid–Schiff stain is especially helpful because it binds to polysaccharides and glycoproteins in the egg wall and in surrounding granulomatous tissue, causing the Schistosoma eggs to stand out as magenta structures against a lighter background. This contrast makes it easier to recognize the characteristic eggs and their location in the tissue.

Giemsa is a general parasite stain often used on blood smears and may help visualize some parasites, but in tissue sections it’s not as specific for the egg structure as PAS. HMWCK highlights keratin in epithelial cells, not the parasite, and Ziehl-Neelsen targets acid-fast bacteria, not schistosome eggs. Therefore, PAS is the stain that best supports identification of schistosomiasis in tissue specimens.